taxonID	type	description	language	source
42378248165DFFECBCE65E4640FDF8AF.taxon	description	NOMENCLATURE. — In the newly created Thoracotremata Guinot, 1977, a superfamily rank Gecarcinoidea was proposed by Guinot (1977 a: 406; 1977 b: 1050; 1978: 287). The family-group name Gécarciniens H. Milne Edwards, 1837 meets all the criteria of availability in accordance with the provisions of the Code (ICZN 1999, Art. 11.7, 11.7.2). However, although authority of H. Milne Edwards is explicitly recognised by many carcinologists and despite that Türkay (1970: 335), Prahl & Manjarrés (1983: 32; 1984 a: 151) and Tavares (1989: in the title and p. 5, 21) formally assigned authorship to H. Milne Edwards (1837 a), the Gecarcinidae continued to be attributed to MacLeay (1838: 63) by most authors, e. g. by Ng et al. (2008: 30, 214), Guinot et al. (2013: 40, table 7), Ng & Davie (2012: 89), Ng & Shih (2014: 112; 2015: 383; 2023: 2), Davie et al. (2015 b: 1117), Ng (2017: 2). Authorship of the family-group name Gecarcinidae was already discussed in detail by Guinot et al. (2018: 602) and Tavares & Mendonça Jr (2022: 9), and is hereby – and we hope – definitively – ascribed to H. Milne Edwards (1837 a).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248165DFFE0BCC15C0440A0F928.taxon	description	Geocarcinus – Miers 1886: 217 (incorrect emendation of Gecarcinus Leach, 1814). — Young 1900: 236, 237.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248165DFFE0BCC15C0440A0F928.taxon	materials_examined	TYPE SPECIES. — Cancer ruricola Linnaeus, 1758, by subsequent designation by H. Milne Edwards (1837 b: pl. 24), see Figs 1 - 4, 6; 10 A, D; 11 A; 16 - 18; 21, Table 1. OTHER INCLUDED SPECIES. — None.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248165DFFE0BCC15C0440A0F928.taxon	description	EMENDED DIAGNOSIS Carapace Carapace much broader than long, globular, with hepatic, subhepatic and branchial regions markedly inflated, even vaultlike; widest part of carapace considerably ahead of antero-lateral angles of mesogastric region; area lateral to the orbits proportionally very large, with fronto-orbital distance in adults about two-fifths carapace width (near half the carapace width in half-grown individuals). Dorsal surface with well-pronounced grooves: cervical groove very deep, terminating anteriorly in a pit near orbital angle; median (or urogastric) groove very deep; longitudinal mesogastric groove very deep, rising towards frontal margin, making certain regions well defined, such as e. g. the gastric and cardiac regions. Numerous striae along lateral margins of carapace. Front long, strongly produced and deflexed, proportionally narrow and slightly widening underneath, with concave lateral margins and upturned lower margin. Mesial lobe of infraorbital margin elongated, curved around ventrolateral edge of front, covered by front edge. Antero-lateral margins rounded; proximally with a short row of more or less marked granules, well pronounced in small and medium-sized male individuals and in females, then tending to largely disappear in very large-sized individuals; then margins smooth. Cephalic structures Antennules very small, folded obliquely. Antennae very short, visible but markedly recessed. Orbits small, englobed in carapace, deep; outer angle not marked. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome not completely covered by triangular median process of subfrontal plate, thus visible. Epistome developed, with one median crest and a lateral crest on each side. Buccal cavity rhomboid. Subhepatic and pterygostomial region glabrous, with many striae. Mxp 3 Mxp 3 (when applied well against buccal cavity) with anterior margin of merus reaching only the epistome or advancing either to the level of the antennules or to the frontal margin (see Phenotypic variations, under Gecarcinus ruricola); leaving between them a narrow rhomboid gap, in which mandibles are exposed. Ischium and merus very unequal, their articulation clearly oblique; ischium smaller and merus elongated, strongly obliquely directed; with marked longitudinal groove. Merus triangular, narrowing anteriorly, with anterior margin entire, not emarginate; meri of both sides more or less joining medially; palp inserted below merus: palp with first article fused to merus internal surface and with two mobile distal articles concealed, not visible. Exopod of mxp 3 completely concealed, apex not reaching ischium-merus articulation, as well visible suboval plate, with lateral dense setae; without flagellum. Chelipeds Adult male chelipeds massive but not extraordinarily enlarged, equal or slightly to moderately subequal, possibly distinctly unequal in large individuals; narrowly gaping; heterochely and heterodonty usually not or slightly marked, possibly occasionally pronounced (Fig. 1 B); occlusal margins of fingers with small, spaced teeth on both sides; in the rare cases of greatly uneven chelipeds (heterochely), a more pronounced gap and pronounced heterodonty (Fig. 1 B). Merus with curved internal surface and with marked denticles on inner lower margin; carpus with conspicuous denticles on upper margin. Sexual dimorphism moderate. Ambulatory legs Very spiny. P 3 propodus with lateral carinae bearing four rows of prominently and similarly developed spines; dactylus with lateral carinae bearing six rows of prominently and similarly developed spines. Sterno-pleonal cavity and pleon Sterno-pleonal cavity completely glabrous, long; its extremity ending either very close to suture 2 / 3 and even almost exceeding it, sometimes very slightly distant, with marked ridge around telson. Male pleon rather long, with all somites free plus telson; margins only with sparse setae; somite 6 with convex margins. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide (especially at level of somite 5); sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate with convex margins; suture 2 / 3 present, V-shaped; suture 3 / 4 absent, without lateral trace; sternites 3 + 4 completely fused, with convex, obliquely directed margins, thus not restricted at level of P 1; sutures 4 / 5 to 7 / 8 interrupted; sternites 5 - 7 similarly shaped, sutures well defined; suture 7 / 8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7 at level of narrow median bridge at level of suture 7 / 8; another weak median bridge at level of suture 6 / 7; deep median line only along sternite 7. Locking pleonal structure as rather large prominence about in middle of sternite 5, but pleonal sockets not delineated, so no longer functional. Setal tufts of more or less dense hydrophilic setae located along first pleonal somites margins and at junction of pleon with carapace. Male gonopore and penis Male gonopore and penis at level of suture 7 / 8, emerging rather far from P 5 coxo-sternal condyle. G 1 and G 2 G 1 tapering at its extremity, with unequal setae at its tip; apex rather long (called ‘ palp’, see Türkay 1970: 336, fig. 1 a-f); laterally, a very long, narrow horny tube (called ‘ Terminalanhang’ by Türkay 1970: 334, or appendix) completely rolled up on itself, with the opening displaced towards its distal extremity, and clearly exceeding G 1 tip; several horny setae at its base. G 2 tiny, without flagellum. Vulvae Protruding, obliquely directed, normally occluded by a rigid calcified immobile operculum (see Hartnoll 1968).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248165DFFE0BCC15C0440A0F928.taxon	discussion	REMARKS In Le Règne Animal of Cuvier, H. Milne Edwards (1837 b: pl. 24) illustrated Gecarcinus ruricola as his representation of Gecarcinus, and, on the basis of the title of this work, this can be considered a type designation. Some authors cite the year 1838, but, according to Cowan (1976), plate 24 was produced in March 1837 (see Ng et al. 2008: 215). The genus Gecarcinus new status differs from Hartnollius n. gen. by many characters, which are listed in Table 1. The level of generality of the distinguishing characters between them is similar to those that differentiate Gecarcinus from Johngarthia, and their number is even greater. No gecarcinid has such a globose carapace and small deeply embedded orbits as Gecarcinus ruricola. According to Britton et al. (1982), during growth an expansion in the lateral carapace dimension provides a small increase in branchial volume but a larger increase in surface area, which presumably facilitates gaseous exchanges with the atmosphere: small individuals (40 mm cw) of G. ruricola have approximately the same branchial chamber surface area than Hartnollius lateralis n. comb., whereas individuals of greater width have increasingly greater branchial area. If greater respiratory surface and respiratory capacity are desirable for G. ruricola, larger individuals will have a selective advantage. As it grows, the carapace swells more and more to accommodate the branchiostegal lung so that the proximal crest of the antero-lateral margin (see Fig. 4 A-C) becomes more and more attenuated until it disappears completely, and the orbits become enclosed in the carapace (Figs 2 A; 17; 18). Several species initially assigned to Gecarcinus were separated by Türkay (1970: 343), who created for them the subgenus Johngarthia, later elevated to generic rank (Türkay 1987). Johngarthia Türkay, 1970 includes the type species Johngarthia planata (Stimpson, 1860), J. lagostoma (H. Milne Edwards, 1837), J. malpilenis (Faxon, 1893), J. weileri (Sendler, 1912), J. oceanica Perger, 2019, and the enigmatic J. cocoensis Perger, Vargas & Wall, 2011. The distinctive characters of Johngarthia mainly concerned the G 1 (short, folded outwards, without a long, narrow horny tube), the merus of mxp 3 with a slit-shaped fissure approximately on the inner margin, and the exopodite of mxp 3 long, with setae extending beyond the ischium-merus articulation. Larval development also distinguishes Johngarthia planata from that of Hartnollius lateralis n. comb. (Cabrera 1966; Cuesta et al. 2007). It is worth noting that Johngarthia lagostoma (see Tavares & Mendonça Jr 2022: fig. 47 A, F) shows some resemblance to G. ruricola in the globular carapace, recessed antenna, long and obliquely directed merus of mxp 3 that reaches almost the front. It is interesting to remind that Tavares (1991) found no synapomorphies to support the monophyly of Johngarthia. Colavite et al. (2021), studying the morphology of the first zoeal stage of J. lagostoma, endemic to the Atlantic oceanic islands of Ascencion, Trindade and Martin Vaz, Fernando de Noronha and the Rocas Atoll, suggested that the uncommon large eyes could be an autapomorphy of the species and again discussed the validity of this genus.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	description	(Figs 1 - 4; 6; 10 A, D; 11 A; 16 - 18; 21; Table 1)	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	materials_examined	TYPE MATERIAL. — Neotype (by present designation). Cuba • ♂ 55.0 × 76.0 mm; in ethanol; de Boury coll. 1914; Bouvier det. as Gecarcinus ruricola; M. Türkay vid. VI. 1972; MNHN-IU- 2017 - 8392 (= MNHN-B 13155). OTHER MATERIAL EXAMINED. — Cuba • 1 ♂ 66.4 × 95 mm; dry; M. Gundlach [coll]; as Gecarcinus ruricola; MNHN-IU- 2000 - 10953 (= MNHN-B 10953) • 1 ♂ 66.2 × 93.3 mm; dry; M. Gundlach [coll]; as Gecarcinus ruricola; MNHN-IU- 2000 - 10955 (= MNHNB 10955) • 1 ♂ 57.7 × 81.4 mm; dry; M. Gundlach [coll]; as Gecarcinus ruricola; MNHN-IU- 2000 - 3764 (= MNHN-B 3764) • 1 ♂ 61.7 × 91.6 mm (as Gecarcinus ruricola; MNHN-IU- 2000 - 3766 (= MNHN-B 3766) • 1 ♀ 60.5 × 83.8 mm; dry; as Gecarcinus ruricola; MNHN-IU- 2000 - 10754 (= MNHN-B 10754) • 1 young ♂ 17.7 × 23.7 mm, same data as neoype; MNHN-IU- 2018 - 5229 (= MNHN-B 13155) • 1 ♀ 52.8 × 69.9 mm; in ethanol; M. Chaper, det. Gecarcinus; MNHN-IU- 2024 - 6554 • 1 ♂ 71.0 × 53.0 mm; Playa Larga, III. 2004; as Gecarcinus ruricola; ZMH-K 65343 • 1 ♂ 21.2 × 27.0 mm, 3 ♀ 17.9 × 22.2 mm, 44.3 × 59.2 mm, one damaged; off Cape San Antonio, Ensenada de Cajon; 21 ° 52 ’ 00 ” N, 84 ° 57 ’ 00 ” W; Tomas Barrera Exp., Henderson & Bartsch coll.; 22. V. 1914; Rathbun det.; R. B. Manning redet.; USNM 48405 • 1 ♂ 51.5 × 71.5 mm, Cabanas, 22 ° 58 ’ 32 ” N, 82 ° 55 ’ 00 ” W; Tomas Barrera Exp.; st. 16 (nec depth 4 - 22 m); Henderson, Brooks & Bartsch coll.; 8 / 9. VI. 1914; USNM 48402 (See Fig. 6 H) • 3 ♂ 52.4 × 73.5 mm, 54.0 × 75.0 mm, 55.9 × 75.5 mm; 4 ♀ cl 52.5 mm, 42.7 × 55.9 mm, 40.9 × 54.7 mm, 53.3 × 71.4 mm; P. Bartsch coll.; 1930; R. B. Manning det.; USNM 71242. Cayman Islands • 1 ♂ 61.2 × 88.0 mm, Cayman Expedition 1938; English Sound, Sta. 31; Coll. & Pres. Oxford University; 11. V. 1938; NHM 2024.353. Little Cayman • 3 ♂ 56.0 × 78.1 mm, 62.7 × 87.7 mm (yellow morph), 58.2 × 82.6 mm (red morph), 1 ♀ 68.0 × 95.2 mm (red morph); Cayman Expedition 1938, 1938; in bush and plantation; 1952.1.17.4 - 6; Coll. Oxford University; 11. V. 1938; NHM 2024.353 [1 ♂ 29.3 × 37.0 mm of this sample is Hartnollius lateralis n. comb.]. Jamaica • 1 ♂ 56.8 × 80.2 mm; Clydesdale; coll. W. Lynn; 1. VI. 1936; alt. 1067 m, Rathbun det.; USNM 72785. Haiti • 1 ♂ 25.4 × 32.0, 1 ♀ 29.0 × 35.6 mm; Coll. D. F. Weinland, MCZ n ° 1613, USNM 1513693 (See Fig. 6 C). Near Haiti, Navassa Island (Isle de la Fortune) • 6 ♂ (60.0 × 82, 9 mm Cr 63, 55.6 × 76.6 mm Cr 64, 55.9 × 75.9 mm Cr 65, 60.0 × 82.7 mm Cr 66, 55.4 × 77.0 mm Cr 67, 54.0 × 76.2 mm Cr 68; I. Sanderson; 16. XII. 1937; det. A. C. Evans; NHM 1967.7.1.80 - 85. (See Fig. 6 A, B). St Kitts • 1 ♂ (many legs detached) 66.6 × 93.8 mm (red morph); 1912.6.18.1; pres. J. J. Quelch; NHM 1888.26. Antilles • 1 ♀ 59.8 × 82.2 mm; dry; as Gecarcinus ruricola; MNHNIU- 2000 - 3765 (= MNHN-B 3765). Guadeloupe • 1 ♂ 74.8 × 109.2 mm; dry; as Gecarcinus ruricola; MNHN-IU- 2000 - 10876 (= MNHN-B 10876) • 1 ♂ 32.7 × 43.4 mm (red morph); Îles des Saintes; KARUBENTHOS 3; Stn IGM 4, 15 ° 52.44 ’ N, 61 ° 34.8 ’ W; 28. IX. 2024; MNHN-ARBig-LPRig coll.; Parasram det.; MNHN-IU- 2024 - 4640; (see Fig. 6 D) • 1 ♀ 41.2 × 54.2 mm, ‘ red morph’; La Désirade; Parc du Souffleur; KARUBENTHOS 3; Stn AU-EP- 09, 16 ° 18 ’ 51.0 ” N, 61 ° 02 ’ 55 ” W, alt. 263 m; dry forest; 10. XI. 2024, E. Poirier MNHN-ARBig-LPRig coll.; Parasram det.; MNHN-IU- 2024 - 7258 (See Fig. 6 E). Dominica • 1 ♂ 65.6 × 91.0 mm; near mouth of Layou River, along road at night; H. H. Hobbs Jr coll.; 14. II. 1966 and det.; USNM 12693 • 1 ♂ 67.3 × 91.3 mm, 1 ♀ 68.0 × 93.6 mm; on cliff above S. shore of mouth of Layou River; H. H. Hobbs Jr & F. A. Chace coll. 9. III. 1964 and det.; USNM 126937 (See Fig. 6 F) • 1 ovigerous ♀ 67.2 × 92.5 mm; coll. J. G. Ramage; 1888.26; NHM 1888.26. Barbados • 1 ♂ 60.0 × 85.4 mm, 1 ♀ 63.2 × 86.6 mm (dark red morphs); Crane Hotel, St. Philip; coastal cliffs; 13 ° 10 ’ 25.96 ” N, 59 ° 44 ’ 65.73 ” W, 28.09.2019; Parasram coll. and det.; BLSZ 059. Curaçao • 1 ♂ 37.8 × 51.4 mm; Caracas Bay, Hato [Hato caves]; 28. IV. 1920; C. van der Horst; USNM 56879. Colombia, Isla de la Providencia • 4 ♀ 63.4 × 83.9 mm, 66.7 × 89.8 mm, 60.0 × 80.6 mm, 55.2 × 71.5 mm; R / V Albatross; S. I. Smith det.; USNM 7343 (See Fig. 6 G). Bahamas • 1 ♀ 59.0 × 81.0 mm; dry, damaged; as Gecarcinus ruricola; MNHN-IU- 2000 - 12496 (= MNHN-B 12496). TYPE LOCALITY. — The previous statement of ‘ America’ by Linnaeus (1758) as type locality must be replaced by the place of origin of the neotype, namely Cuba. DESIGNATION OF A NEOTYPE In order to fix the taxonomic identity of Gecarcinus ruricola, we undertook the necessary steps to trace the type of Cancer ruricola Linnaeus, 1758, first by consulting the Catalogue of the ‘ Linnaean collection’ held at Uppsala University, and then by contacting the Linnean Society of London, which provided us with a list of ‘ Linnaean type specimens’, including Crustacea, deposited at that institution (Wheeler 1983). No specimen with this name has been found in these two institutions and therefore no name-bearing type specimen is considered to be extant (ICZN 1999: Article 75.1). In order to define and typify G. ruricola objectively by a single specimen, a neotype is designated here. As the neotype must come “ as nearly as practicable from the original type locality ” (ICZN 1999: Article 75.3.6), in our case from ‘ America’, a Cuban representative (Figs 2; 3 A-F) is well suited to be a candidate for the neotype since Linnaeus had received material from various places in America, including this island, for his Systema Naturae.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	diagnosis	DIAGNOSIS Like the genus Gecarcinus new status, which is represented by the one and only species G. ruricola.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	discussion	REMARKS According to Hartnoll et al. (2006 a: table 6), in San Andrès, the species is heterochelic, with no preferential handedness. The larger size of male chelae is small compared to other gecarcinoid species. Growth patterns of the chelae result in modest levels of heterochely and sexual dimorphism. This suggests that both sexes play roles of similar dominance levels during intraspecific interactions. In the material examined, the chelae of male G. ruricola are subequal, without marked heterochely and heterodonty (Figs 1 A; 3 A, B; 4 B; 10 D; 17; 18), however with exceptions (see Fig. 1 B). There appears to be no genetic predisposition for right-handedness in Gecarcinus ruricola. During the night and when disturbed in their burrows during the day, Hartnollius lateralis n. comb. and H. quadratus n. comb. are known to produce sounds (Klaassen 1973: figs 1 - 5, and Abele et al. 1973: fig. 1, respectively) by friction of the merus of the cheliped against the subhepatic region of the carapace, which bears a number of oblique rows of striae (pars stridens) (Figs 12 A; 14 A, respectively). However, in the case of Gecarcinus ruricola, which has similar striae in the same region (Figs 2 B; 4 D; 18 B), this type of communication does not seem to have been reported.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	description	SIZE Besides Gecarcoidea natalis (Pocock, 1888), from Christmas Island, Indian Ocean, which can exceed 120 mm cw (see Green 1997), Gecarcinus ruricola reaches very large sizes, with a modal size of 97 - 110 mm cw and a maximum recorded of 123 mm cw (Van der Hoeven & Walters 1998; Hartnoll et al. 2006 a: figs 2, 3). It is one of the largest American gecarcinids, making it a ‘ museum piece’ (Richmond 2003) (Figs 1; 2). The mean carapace width of all measured Hartnollius lateralis n. comb. was approximately half that of all measured G. ruricola, whereas the mean fronto-orbital distance of H. lateralis n. comb. was less than half that of G. ruricola (Britton et al. 1982: fig. 3), i. e., the carapace of G. ruricola lateral to the orbits is proportionately larger than the corresponding area of H. lateralis n. comb. The mean size of adult G. ruricola is known to differ among the Caribbean Islands: for example, throughout the Grand Cayman both sexes are smaller in terms of body size than other populations in the Caribbean and males are larger than females (see below, Biology); by comparison, H. lateralis n. comb. shows an increase in mean size from eastern to western localities. G. ruricola has by far the most inflated carapace. COLOUR Phenotypic plasticity in colour patterns is very often observed in land crabs, and multiple morphs can be recognised in the same species. Gecarcinus ruricola is known to exhibit extensive colour polymorphism, with at least four main colour morphs: black, red or purplish, yellow and green, some with subpatterns, as follows. Martinique: carapace and legs intense purplish or dark morph (Fig. 17 A); Dominica: black morph that has a rich purple dorsal surface of carapace, with reddish overtones and various spots (Fig. 18 H) (Chace & Hobbs 1969), and yellow morph (Fig. 18 G); Saint-Barthelemy: a green morph mixed with other colours (Fig. 18 A), a red morph (Fig. 18 B) also an intense purplish morph or black morph (Fig. 18 C); Anguilla: a mixed colour morph (Fig. 18 E), a black morph (Fig. 18 F) and a yellow morph (Fig. 18 D); Grand Cayman: black morph, and subpatterns. The mesial lobe of infraorbital margin is very often, whatever the island and the morph, intensely red (Figs 17; 18). In Puerto Rico, G. ruricola has different colours on the carapace, chelae, and legs: some carapaces have varying intensities of purple, from dark to light, blue, and varying intensities of yellow / orange (Rodríguez-Fourquet et al. 2025: fig. 6). The Grand Cayman ‘ black crab’ exists in three different colour morphs (Stensmyr et al. 2008: fig. 1 A, D), but this information must be corroborated because the figure E of the same authors seems to belong to Hartnollius lateralis n. comb. In Cuba, Gecarcinus ruricola displays two different patterns: the black and light tan or yellow morphs (Chace 1940: 53). A study of colour polymorphism in the G. ruricola from western Cuba, in the Parque Nacional Ciénaga de Zapata (one of best bird watching areas in the world) has identified two different patterns: black and yellow morphs, without any statistically significant difference for the frequency of the yellow colour neither between sexes nor between years; and the relation cheliped-body weight compared between both colours gave similar result (Acevedo 1989: figs 2 - 4, table 1). A striking but variable red / purplish morph is observed in Cuban G. ruricola from La Blanquilla (Scelzo & Varela 1988: fig. 4), which can lead to confusion with Hartnollius lateralis n. comb. (Fig. 19). A mixed colour morph is also present in Cuba (Fig. 17 B). For Gecarcinus ruricola there are no studies focusing on the colour patterns and the significance of the colour diversity. Such a study has been conducted, for example, on Cardisoma guanhumi from northeastern Brazil, where the four identified colour patterns could be clearly related to the crab’s stage of development (growth size) and sexual maturity, with the smallest individuals being bright orange and the sexually mature adults ranging from brown to blue (Silva et al. 2014). It is also possible that colour patterns may change depending on seasonality and the current state of the individual (stress, endogenous rhythms or even temperature variations). They could also be related to osmoregulatory and respiratory physiology, response to desiccation, moult cycle and mating behaviour (Reid et al. 1997; Silbiger & Munguia 2008). In comparison, in Johngarthia lagostoma from Trindade Island (Brazil), colouration varies depending on individual size, sex and ecological processes related to differential occupation of available habitats: there are three colour types (black, purple and yellow), with black crabs being exclusive and predominant in the smaller size classes; then, yellow crabs dominate throughout ontogeny, while purple individuals are less frequent. Crabs of all three colour types are present in both sexes, and the frequency of each type are similar in males and females. Black and purple crabs primarily occupy hill areas, whereas yellow crabs predominate throughout the island. Camouflage by background matching appears to be particularly important for small black crabs at recruitment (beach sand) and resident areas (hills vegetation and soil), where individuals exhibit higher colour matching types in both sexes. The frequency of each type, their brightness and colour metrics are similar between beaches and resident areas (hills vegetation and soil), where individuals exhibit higher colour matching (João et al. 2023). VERNACULAR NAMES Gecarcinus ruricola is known as the ‘ black land crab’, ‘ purple land crab’, ‘ red land crab’, ‘ mountain land crab’, ‘ zombie crab’, ‘ Halloween Krabbe’, and ‘ blue crab’. It may be given the surname of ‘ tourlourou’ or ‘ touloulou’ (as in the French Antilles, see Fig. 4 A, B), as well as other species of Gecarcinidae, e. g. Hartnollius lateralis n. comb. (see below, Identity of land crabs synonymised with Gecarcinus ruricola or G. lateralis in the literature). For the pre-Linnaean nomenclature of gecarcinids, see Holthuis (1959) in his C rustacea Decapoda of Suriname. Holthuis (1959: 7) explains that Labat (1724: 47 - 53) described the species ‘ Tourlouroux’ (Gecarcinus spec.), ‘ Crabes violettes’ (= Gecarcinus spec.), ’ Crabes blanches’ (= Cardisoma guanhumi Latr.), and that the Suriname species identified by Fermin (1765) as ’ Crabes violets’, ‘ Crabes blancs’ are not the species referred to by Labat but are Ucides cordatus (Linnaeus, 1763) and Ocypode quadrata (Fabricius, 1787), respectively. In fact, only Cardisoma guanhumi is found in Suriname, and its distribution area extends from Brazil to Bermuda, Bahamas, Southern Florida and the West Indies (Holthuis 1959: 259, pl. 12). UPDATED GEOGRAPHICAL DISTRIBUTION Gecarcinus ruricola is found without discontinuity throughout much of the Caribbean, only on islands. From the Bahamas and Cuba in the west it extends through the Greater and Lesser Antilles to Barbados in the east, i. e., Jamaica, Hispaniola, Cayman Islands, St. Croix, Saint Martin, Saint-Barthelemy, Saba, Montserrat, Guadeloupe, Martinique, Dominica, Barbados (see Hartnoll 1988 a: fig. 2.6). Outlying populations occur on Curaçao, Aruba, Bonaire, Blanquilla, and in the western Caribbean in the Swan Islands off Honduras, Half Moon Caye of the Belize Barrier Reef; and also the Archipelago of San Andrés, Old Providence and Santa Catalina, off the Caribbean coast of Colombia (Powers 1977; Abele & Kim 1986; Hartnoll et al. 2007). It is common on some Caribbean islands, but less in others. There were very few records of Gecarcinus ruricola for continental America and, moreover, they have not been confirmed (Hartnoll & Clark 2006). The record from Florida (Rathbun 1918: 355) is only supported by specimens from Loggerhead Key in the Dry Tortugas, where the species was considered rare (Powers 1977; Bliss et al. 1978). The location in southeastern Florida by Chace & Hobbs (1969) and Keith (1985) has not been confirmed by other sources, and no specimens or locations are cited (Hartnoll et al. 2006 a). Our examination of the NMNH material leads to the elimination of G. ruricola from continental America. In fact, Rathbun’s record from ‘ Florida’ (cited e. g. by Chace & Hobbs 1969; Keith 1985; Luque 2017) does not apply to G. ruricola. The records ‘ nS Am’ and ’ E Fla’ in Felder et al. (2009: 1088) are also erroneous. The two males and two females from the Florida Keys, Loggerhead Key (USNM 71219) (Fig. 5 A, B) were misidentified as G. ruricola by Rathbun (1918) and are in fact typical Hartnollius lateralis n. comb. Similarly, references to ‘ Nicaragua’ mentioned by Chace & Hobbs (1969) and Keith (1985) but not confirmed by other sources, and the absence of citations of other specimens from this location (see Hartnoll et al. 2006 a) correspond to a misidentification. Our examination of the material (two males) (Fig. 5 C, D) from Nicaragua, Greytown (USNM 74612), labelled as Gecarcinus ruricola by Rathbun, but later annotated “ looks like to me G. lateralis ” by H. L. Carson, and reidentified as G. lateralis by F. H. Barnwell, shows that these crabs are indeed Hartnollius lateralis n. comb. Due to the absence of G. ruricola in continental America here confirmed, G. ruricola would be restricted to the Caribbean Islands and would be an insular species (see Garth 1976 for comments on insular species), which makes previous accounts of its distribution inaccurate. Note that a crab from Isabel Island, Sinaloa, Mexico, a male 66.0 × 94.0 mm, W. C. Swettt coll. (‘ red land crab’), 19. III. 1933, Rathbun det. (USNM 139315), was misidentified and, according to our examination, is in fact the eastern Pacific land crab Johngarthia planata (see Samaniego-Herrera & Bedolla-Guzmán 2012; Perger 2019). The report of G. ruricola in the North of Mexico by Leija-Tristán (1985) is most likely Hartnollius lateralis n. comb. The mention of ‘ Ecuador (Cano, Nobili) ’ by Rathbun (1910: 612; 1918: 357) regarding the distributional range of Gecarcinus lateralis is somewhat confusing because the Gecarcinus of Cano (1889: 101, 227) and Nobili (1901: 46), both from Ecuador, are cited by these two authors as G. ruricola. This formulation by Rathbun (1910, 1918) is explained by the fact that she attributed these G. ruricola specimens from the Pacific coast to G. lateralis. The G. ruricola of Cano and Nobili were later assigned to G. quadratus by Garth (1948: 59). The crab of Nobili (1901) gave its name to G. nobilii Perger & Wall, 2014, now Hartnollius nobilii n. comb. (see Perger & Wall 2014). Although Perger & Wall (2014) do no mention the G. ruricola of Cano (1889: 101, 227) from the same region, Ecuador, it is likely that this specimen also belongs to Hartnollius nobilii n. comb. PHENOTYPIC VARIATIONS We assembled abundant material of Gecarcinus ruricola, a species widespread in many and diverse Caribbean islands, but also reported on the continent, to detect possible intraspecific variability or the presence of cryptic species. Since the few previous records of G. ruricola from continental America had never been confirmed, it was necessary to review this issue in depth. Our examination has evidenced that the continental species assumed to be G. ruricola were in fact Hartnollius lateralis n. comb., see above Updated geographical distribution; and Figure 5. The main variation observed concerns the mxp 3 (when firmly applied against the buccal wall) and the level reached by the extremity of the sterno-pleonal cavity in relation to the thoracic sternal suture 2 / 3, which somewhat varies, being either straight or slightly concave (Fig. 6). An extreme condition, with maximum anterior extension of the mxp 3 and complete coverage of the buccal cavity, is found in Gecarcinus ruricola from Haiti. We examined two lots: one from the NMNH (USNM 1513693, with one male and one female, both small); and another lot from the NHM (NHM 1967.7.1.80 - 85 with six large males) from the vicinity of Haiti, namely from Navassa Island (‘ Isle de la Fortune’). These Haitian individuals are characterised by a remarkable feature, that of having their mxp 3 reaching the frontal border, and even exceeding it in some, and the meri on each side being entirely joined medially (except at the level of the mandibles), with an irregular latero-internal margin (Fig. 6 A-C). The two external maxillipeds form a complete cover to the more internal mouthparts, with only part of the mandibles and some small portions of other maxillipeds being exposed. Therefore, the latero-external margin of the merus is very close to the infraorbital ridge. A character that appears concomitant is the close proximity of the extremity of the sterno-pleonal cavity to the thoracic sternal suture 2 / 3 (Fig. 6 A-C). When compared in all the Haitian specimens we have examined, the mxp 3 merus is more or less oval, more or less elongated, and more or less obliquely directed, which demonstrates that this structure is somewhat variable, even among crabs within a population that appears homogeneous. See below under Gecarcinus depressus Saussure, 1857.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	materials_examined	Considering Gecarcinus ruricola from other Caribbean islands, it is clear that the condition of mxp 3 is variable. Forward extension and covering of the buccal cavity are observed in crabs from other localities than Haiti, to varying degrees. For example, the small male and female from Guadeloupe collected during Karubenthos 3 Expedition (Fig. 5 A, B) show a similar extension of the mxp 3 (Fig. 6 D, E): the merus reaches the front, and its internal border is slightly concave; each merus joins that of the other side; the extremity of the sternal cavity reaches the sternal suture 2 / 3. The pattern is the same in G. ruricola from Martinique (Fig. 17 A). The extension is quite pronounced in a male G. ruricola from Dominica (Figs 6 F; 18 G). In a small male cw 75.9 mm (USNM 2065) and two larger males 60.0 × 85.3 mm, 63.1 × 86.5 mm (BLSZ 059) from Barbados, as well as in a male 66.6 × 93.8 mm (NHM 1888.26) from St Kitts, the mxp 3 are much extended and leave only a very short space between the anterior margin of merus and the front. In a male from Jamaica, the merus reaches the antennules, as in the large male cl 67.0 mm represented by Chace & Hobbs (1969: fig. 66) where the merus covers the epistome and most of the antennular cavities. In specimens of Cayman Islands, the merus reaches either the antennules or only the epistome. On Providencia Island, Colombia, all four females examined have the anterior part of the mxp 3 reaching only the epistome but to a variable extent (Fig. 6 G). In the material from Cuba, individuals have their mxp 3 reaching either the level of the front (Figs 17 B) or the antennules or only that of the epistome as in the neotype (Figs 2 C-D; 10 A); in another specimen (Fig 6 H: see right mxp 3), the space between the merus and the frontal margin is more or less pronounced. As these are only occasional and isolated examples, or at least studies involving a far insufficient number of individuals, the above remarks may be biased and may not represent the overall morphology of the external mouthparts in all individuals in the populations of the countries considered. The first male gonopod is known to be the most reliable character for taxonomic decisions (see Toledano-Carrasco 2019: figs 14 - 19, the numerous figures of H. lateralis n. comb. and H. quadratus n. comb., as Gecarcinus), but, despite careful examination of the G 1 in Gecarcinus ruricola crabs from various islands, we did not detect any possible variation, at least under a binocular microscope. The phylogenetic tree based on the mitochondrial genes COI and 16 S (Fig. 16), as well as the COI-based genetic distance matrix (Table 3), do not reveal any significant differences between the samples from Cuba and Guadeloupe. We therefore assume that Gecarcinus ruricola is a species with intraspecific variability and whose interbreeding populations are reproductively compatible. To corroborate this hypothesis, it would be interesting to include more specimens from different localities in a more in-depth study of the species. It is possible to assume that actually or potentially interbreeding populations are reproductively compatible with other populations The pelagic lifespan of G. ruricola is likely to be of 40 - 50 days and, if water currents are conservatively paced at 1 - 2 knots, then this would give a potential dispersal range of between 2000 to 4500 km. This potential larval dispersal (see Garth 1976) is sufficiently strong to indicate potential intermixing between Caribbean populations of the species (R. Hartnoll, pers. comm.). We currently have - with material insufficiently representative of a population – no decisive morphological argument in one direction or the other: for example, all Haitian specimens examined from three different lots exhibit a similar morphology of the mxp 3 (Fig. 6 A-C) but, on the other hand, the specimens from Cuba show a mxp 3 merus either extending to the front (Fig. 17 B) or reaching only the antennules, or the epistome only (Fig. 6 G). Could the low phenotypic disparity observed, which, at this stage, does not, in our opinion, imply taxonomic changes, be related to genetic divergence? The DNA analyses (although limited) of individuals from the Caribbean islands does not demonstrate the existence of cryptic species in a possible G. ruricola complex.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	biology_ecology	BIOLOGY Gecarcinus ruricola inhabits damp, shaded forest areas or dry upland habitats, retiring into rock crevices or sheltering between tree roots or hiding under fallen trees, sometimes muddy beaches, which distinguishes it from the other three species of Hartnollius n. gen. (see Wolcott 1988: fig. 3.1, as Gecarcinus). The population biology of G. ruricola, studied in the western Caribbean, particularly on two islands of the San Andrés Archipelago, San Andrés and Old Providence / Santa Catalina Islands (Hartnoll et al. 2006 a), reveals that the ‘ black land crab’ is the most terrestrial of gecarcinids in the Caribbean (some of endemic Jamaican sesarmids are more terrestrial overall). It feeds on fruits, mushrooms and other organic matter from the forest. In Dominica, G. ruricola is found several kilometres inland from the sea, up to 300 m (Chace & Hobbs 1969), and up to 1000 m in Jamaica (Britton et al. 1982) and in the San Andrés Archipelago (Hartnoll et al. 2006 a); it can even live several kilometres inland (Wolcott 1988). G. ruricola (‘ black land crab’) is found throughout Grand Cayman (such as Cardisoma guanhumi): males reach a larger maximum size than females, both sexes are smaller in terms of body size than other populations in the Caribbean (it may be possible the populations on Grand Cayman reach sexual maturity at an earlier stage and smaller size than other geographic locations), and the reproductive migration season extends over three months on Grand Cayman (Tedford 2018). The lateral regions of the carapace are inflated to accommodate the highly modified respiratory structures. Its biometric characteristics, distribution and activity have been compared to those of Hartnollius lateralis n. comb. by Britton et al. (1982, as Gecarcinus lateralis). Burrowing is somewhat incidental in G. ruricola, whereas H. lateralis n. comb. is an active burrower (Wolcott 1988: fig. 3.9) and even moults within its burrow (Weitzman 1963; Bliss 1968; Bliss et al. 1978, as G. lateralis). G. ruricola is frugiforous and mainly nocturnal (Rodríguez-Fourquet et al. 2025), except during the breeding migration, whereas H. lateralis n. comb. can demonstrate striking diurnal activity, for example in the Cayman Islands forest (Britton et al. 1982, as G. lateralis) and is mostly herbivorous / omnivorous (Linton & Greenaway 2007: table 3, as G. lateralis), sometimes cannibalistic (Wolcott & Wolcott 1984, as G. lateralis). Carson (1967), Carson & Wheeler (1967) and Stensmyr et al. (2008: fig. 1, as G. ruricola and G. lateralis; see also Stensmyr & Hansson 2007, as G. lateralis) described the symbiotic relationships of G. ruricola (and also H. lateralis n. comb.) with drosophilids in the West Indies (see also Bright & Hogue 1972: table 1, as Gecarcinus) and in Puerto Rico (Rodríguez-Fourquet et al. 2025: fig. 7, as Gecarcinus ruricola). Protists have been found in the digestive tract of H. lateralis n. comb. (Perger et al. 2022). Gecarcinus ruricola and Hartnollius lateralis n. comb. are sympatric in many areas of the Caribbean. Britton et al. (1982, as Gecarcinus lateralis), who conducted comparative biometric analyses, habitat preferences, activity patterns and other biological data on these two species, highlighted the paucity of literature on G. ruricola within its range (in contrast to the extensive literature on H. lateralis n. comb.; see under that name), despite it is one of the most conspicuous terrestrial crustaceans, captured and used as food. The increasing presence of human activities in the Caribbean may deprive G. ruricola of suitable habitat and thus reduce its numbers. The study of the reproductive biology of Gecarcinus ruricola in the San Andrés Archipelago by Hartnoll et al. (2007) provides extensive details on breeding females, annual breeding migration, egg laying (migrating crabs are mostly females with predominance of ovigerous females with the eggs carried under the pleon; some females mate and lay eggs on the landward side, others on the seaward side (see Fig. 21 A), migrating females on average are larger than migrating males), fecundity and irregular recruitment. The megalopa of G. ruricola is the most terrestrially adapted megalopa described to date for locomotion on land: it is the returning stage from the sea to the terrestrial habitat (Hartnoll & Clark 2006: 162, figs 3 - 9, table 2). There are sometimes extensive land invasions by megalopae, with pink mass of megalopae crossing the landward side of the coast, a hasty moulting to the first crab and swarming into the forest. But such an invasion is not an annual event. The megalopa is the stage which invades land and normally travels overland some distance before moulting; the migration of berried females to the sea varies in timing and intensity from year to year, with, however, a substantial migration each year (Hartnoll & Clark 2006: 162, fig. 2; Hartnoll et al. 2014: 532, fig. 1). A similar land invasion by megalopae occurred in Jamaica in 2006 (Aiken & Pal 2009). And, in Cuba, crabs (red, yellow or black) sometimes emerge by the millions and head towards the sea to deposit their fertilised eggs in the water, mating having previously taken place in underground burrows. In Puerto Rico, where site fidelity is present (except during migration), only female migration has been observed, meaning that copulation occurs far from the shore and in the forests, which males therefore do not abandon (Rodríguez-Fourquet et al. 2025). If this is confirmed, there would be a notable difference with land crabs such as the ‘ red crab‘ Gecarcoidea natalis (Pocock, 1888) on Christmas Island, in which males and females migrate together to the sea and mate there, then the males return to their main residence, while the females remain on the shore to lay their eggs and release them in the sea, before heading towards the forests; a mass recruitment is observed approximately every five years (Hicks 1985; Hicks et al. 1990). ROLE OF GECARCINUS RURICOLA AND ITS STATUS AS AN ENDANGERED SPECIES As other gecarcinid land crabs, Gecarcinus ruricola is an ecosystem engineer and plays an important role in nutrient recycling and seedling propagation in coastal forests. Given the predicted future decline in precipitation for the Caribbean, the effects of dehydration on feeding preferences of G. ruricola were investigated on the Eleuthera Island (Bahamas) by McGaw et al. (2019). Gecarcinus ruricola is a major source of protein and economic subsistence in many countries. It is known to have an extraordinary flavour. It is a popular food item, harvested on many Caribbean islands and offered live in markets (Burggren & McMahon 1988: fig. 3.12 B). According to Carson (1974: 3518), “ relentlessly hunted down in the populated parts of its range, it remains today principally on small, isolated islands ”. In Puerto Rico, the species is uncommon, and its harvest is prohibited, suggesting that other factors are affecting the population; G. ruricola is classified as vulnerable by Puerto Rico’s Department of Natural and Environmental Resources (Rodríguez-Fourquet et al. 2025). In the San Andrés Archipelago, Colombia, on the tiny island of Providence in the southwest Caribbean about 140 miles east of, Bluefields, Nicaragua, Gecarcinus ruricola, the ‘ Cangrejo Negro’ or ‘ black land crab’ (Fig. 21) is a cultural symbol of the traditional patrimony, a figure in folklore, and plays an important role within the socio-economic structure of the local demography. Crabs of this species are a major local food source: its extraction and commercialisation is considered the third tier of the economy in Providencia (and also Santa Catalina), because approximately 139 families depend exclusively on black crab commercialisation to survive. Due to indiscriminate and illegal hunting, overexploitation, forest reduction, predators and difficulties in surviving during breeding and migration periods, G. ruricola is one of the endangered species of these islands. As a result of the glaring lack of information on Gecarcinus ruricola, the Final Report in April 2005 of the Darwin Initiative for the Survival of Species launched the project “ Sustainable Management of the Black Land Crab, Gecarcinus ruricola, Colombia (162 / 11 / 015) ”, which, for example, supported the papers of Hartnoll et al. (2006 a, 2007) on the biology and reproduction of this species in San Andrés. According to Baine et al. (2007), the exploitation of G. ruricola in San Andrés for human food is so extensive that the Colombian government has established closed fishing areas, closed seasons, and minimum catch sizes. The ‘ Providencia Black Crab Presidium’, created to ensure the preservation of a marine and coastal ecosystem and the survival of species that represent an important source of income, is supported by IFAD (International Fund for Agricultural Development) and the European Union, with the collaboration of several strategic local partners (see Slow Food Foundation for Biodiversity, Providencia Black Crab). On April 1, 2024, the CORALINA Corporation [for the Sustainable Development of the Archipelago of San Andrés, Old Providence and Santa Catalina], “ announced to all inhabitants of San Andrés Providencia and Santa Catalina, that from April 1 to July 31, the ‘ black crab’ ban period begins, in accordance with resolutions 156 of 1993 and 1132 of December 30, 2005, for this reason the appropriation, access, capture, possession, extraction, transportation, commercialization or in any other way, the use of the species or derived products is prohibited. ” San Andrés natives are known as ‘ black crabs’, and sociologists have coined the term « crab antics » to refer to West Indian cultural behaviours (see Darwin Initiative for the Survival of Species, a UK government grants scheme, notably for biodiversity conservation). The ‘ Crab antics’ (i. e., the antics done by the crabs) in San Andrés and Providencia is a metaphor based on the observation of fishermen catching crabs and putting them in an open basket or barrel: the crabs quickly pull down any crab that tries to get out of the basket on its own; if they had cooperated, they could have easily escaped from the basket, but they did not: the lack of cooperation leaves everyone at the bottom of the basket. For a discussion of ‘ crab antics’, see Wilson (1973, 1995, 2017). ‘ Crab barrel syndrome’ (CBS) is similar: no crab can actually get out of the basket, and a person with CBS does not want to see anyone progress except for himself (Uzum & Ozdemir (2020), and ‘ Crab mentality’ or ‘ crab theory’ refers to successful individuals that are seen as a threat by those who want to maintain their position and power, ensuring the collective demise (Tagle 2021). Gecarcinus ruricola is threatened in the Lesser Antilles by rats (Pascal et al. 2004). PHILATELY Gecarcinus ruricola is represented on a multitude of postage stamps from West Indies, notably Cuba, and other Caribbean countries (Omori & Holthuis 2000, 2005). The species was featured on two African postage stamps (Tanzanian and Ugandan stamps) for the International Year of the Ocean in 1998, under the name ‘ mountain crab’. ON THE IDENTITY OF LAND CRABS SYNONYMISED	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481651FFF2BCDF5D874374FE55.taxon	description	WITH GECARCINUS RURICOLA OR G. LATERALIS IN THE LITERATURE Ocypode ruricola Latreille, 1803 Latreille (1803: 35 and footnote) described Ocypode ruricola with the following features: carapace regularly domed, without edge; dorsal prints short, confused; carpus and palms little ornamented; tarsi with spiny edges; found ‘ in America between the two Tropics and in their neighbourhoods, perhaps not living further than the neighbouring places of the Line (the Equator) ’. Regarded as Gecarcinus ruricola by H. Milne Edwards (1837 a: 26) and Young (1900: 239, as Geocarcinus ruricola), it would be Cardisoma guanhumi according to Rathbun (1918: 341); nevertheless, the figures of Latreille (1803: pl. 44 fig. 2), copied from Herbst (1783: pl. 4 fig. 37, as Cancer ruricola), represent the true G. ruricola. There is no crab labelled Ocypode ruricola in the MNHN collection. Ocypode tourlourou Latreille, 1803 In the same paper, Latreille (1803: 36) established Ocypode tourlourou from Santo Domingo, for a large species, generally pale yellow, almost whitish, sometimes washed with reddish and presenting the following characters: chelipeds practically unarmed; major cheliped on the right with the fingers bearing a molariform tooth, and a smooth carpus with a small internal tooth; ventral surface with black setae (‘ poils noirs’); and merus of the legs unidentate. Latreille added that the only figure of Seba [Cancer terrestris] that is suitable for this species is that of t. III, pl. 20, fig. 5 (see Seba 1734 - 1765). This species, not mentioned by H. Milne Edwards (see 1837 a: 26), was considered, without further explanation, to be a true Gecarcinus ruricola by Rathbun (1918: 352), Chace & Hobbs (1969: 200) and Türkay (1970: 336) [who does not mention the Latreille’s O. ruricola]. No crab bearing the name Ocypode tourlourou is present in the MNHN collection. ‘ Tourlourou’ is a popular term given during the First World War to infantry soldiers who wore a blue jacket and madderred trousers. Sailors arriving in the Antilles nicknamed the red crabs ‘ Tourlourous’. ln French Guyana, ‘ Tourloulou’ denotes any disguised and masked person, alluding to the expression ‘ Tour le loup’, which refers to women wearing a mask and whirling while dancing in ballrooms (Belfort 2013). Land crabs in Fréminville (1835) Fréminville (1835: 215) wrote: “ Linnaeus was the first to characterize, under the name of Cancer Ruricola, the common Tourlouroux of the Antilles; and of all the descriptions that have since been made of this land crab, his is still the best; but nevertheless, his successors, either through negligence or lack of opportunity to observe better, have reported and confused with his Cancer Ruricola, two or three distinct species which we will make known below. ” Fréminville (1835: 215, 216, 217) later wrote: “ We are applied particularly to observing land crabs or Tourlouroux and we first noticed that among those understood to this day by naturalists under the names of Cancer Ruricola, Ocypoda Ruricola and Gecarcinus Ruricola, of which they are one and the same species, we could recognise them three distinct ones as Mr. Bosc had already suspected. It is therefore not surprising that the authors differ among themselves in the descriptions they give of the Tourlourou ”. Fréminville retains the name of Ocypode Ruricole for the one of the three species “ that is the most common and is the true Cancer Ruricola of Linnaeus ”, and describes its morphology (too vaguely to be identified), its colour pattern and its biology (” lives in the woods and feeds there on leaves, fallen fruits and generally on plant substances ”; never carnivorous unlike other gecarcinids; nocturnal; digs burrows; runs with such speed that it seems to glide rather than run, so that it is very difficult to catch, and rushes into the burrow, which serves as its retreat). An Editor’s note (p. 213) indicates that it is probably Cardisoma guanhumi. Then, Fréminville (1835) lists four taxa: 1. The Ocypode Ruricole or common Tourlourou. Ocypoda Ruricola, Fabricius, Bosc. Cancer Ruricola Linnaeus. Gecarcinus Ruricola, plates from the Encyclopedia. See Bosc (1830: 252): “ It is found in America, where it is known as Land Crab. There are probably several species confused under this name ”. 2. The great Tourlourou. Ocypoda gigantea N. [i. e., Nobis] This ‘ dirty white’ crab (see Fréminville 1835: 221) is Cardisoma guanhumi, according to an Editor’s note (p. 213) and to Chace & Hobbs (1969: 195). 3. The red Tourlourou. Ocypoda rubra Fréminville (1835: 222) from Antilles. According to the Editor’s note (p. 213), it seems to be the real G. ruricola. It was synonymised with Gecarcinus ruricola by Rathbun (1918: 352) without any comment, then by Türkay (1970: 336), Prahl & Manjarrés (1984 a: 154), and Ng et al. (2008: 215). However, Ocypode rubra might not be Gecarcinus ruricola but could be G. lateralis (i. e., Hartnollius lateralis n. comb., see below), which is red and digs oblique, complex burrows near the shore. The fact that it “ stands as a sentinelle near the opening, and runs very fast ” leaves some doubt. Ocypode agricola Reichenbach, 1836 (p. 230, 231) (see Reichenbach 1828 - 1836) We attempted to locate the specimens from the Antilles that were used by Reichenbach (1836: 230) to establish Ocypode agricola. As was customary at the time, the species was described vaguely and summarily: carapace blood-red; sides raised; margins rounded; orbits round. It lives in holes, is nocturnal, and migrates to the sea and then to land. O. agricola was synonymised with Gecarcinus ruricola by Rathbun (1918: 352) without any comment, and later by Türkay (1970: 336) and Ng et al. (2008: 215). The species is rarely mentioned in the chresonymy of G. ruricola, except by some authors such as Chace & Hobbs (1969: 200), Prahl & Manjarrés (1984 a: 154), Questel (2019: 26) and Schweitzer et al. (2023: 2). With the help of curators and researchers from various German institutions, we learnt that Reichenbach studied in Leipzig and that the remarkable collection of the “ Zoologisches Institut Leipzig ” is now part (at least) of the Crustacean collection in Dresden. It seems that three specimens in two lots (dry and partly in poor condition) from the Antilles bearing the name ‘ Gecarcinus ruricola (Linnaeus, 1758) ’ and registered « Crustacea - SNSD » were found in the Dresden Collection: but, supposedly purchased later, in 1881, from Flesche, they would probably not be the original Reichenbach’s specimens, collected earlier (Andreas Allspach and A. Reimann, pers. comm.). Moreover, if the type of O. agricola was included in the Crustacean collection of Dresden, a town destroyed in 1945, it must be considered lost (A. Reimann, pers. comm). Although the crabs listed in the Catalogue of the old Leipzig Collection (started in 1870) are not registered as the syntypes of Ocypode agricola, we nevertheless give here some photographs (kindly sent by A. Reimann) of the three specimens from the Antilles (two lots): the mesial lobe of the infraorbital margin just joining front margin in all three specimens (Fig. 7 B, E, G) indicates a true Hartnollius lateralis n. comb. (Figs 10 B; 12 B, C; 19); although the anterior margin of mxp 3 merus is not notched and is only barely concave, thus not really concordant, it is not distally triangular as in G. ruricola: it would be only a variation of H. lateralis n. comb. No specimens of Reichenbach appear to be part of the collection of the Leipzig University (Robert Klesser and Bernhard Detlef, pers. comm.). Gecarcinus depressus Saussure, 1857 Saussure (1857: 305; 1858 a: 439, pl. 2 fig. 14, a-c; 1858 b: 23, fig. 11) established for two very small specimens from Haiti a new species, Gecarcinus depressus, “ due to the remarkable configuration of its maxillipeds which seems to indicate a special group within the genus Gecarcinus ”, without any comparison with G. ruricola, but with a detailed description, with characters as follows. The mxp 3 merus is oval, much less wide than the ischium, does not narrow towards the front and barely narrows towards the back; its anterior margin is subnotched (‘ subéchancré’), and the dactylus of the legs has four rows of spines. G. depressus was synonymised with G. lateralis (under its former name, see below under Harnollius lateralis n. comb.) by Rathbun (1918: 355) without any comment, then by Chace & Hobbs (1969: 198), Türkay (1970: 337) and most authors. The suggestion by Miers (1886: 218, and footnote, as Geocarcinus depressus) that this species might not be distinct from Gecarcinus lagostoma, now Johngarthia lagostoma (H. Milne Edwards, 1837), cannot be accepted because the mxp 3 merus is subnotched on the anterior margin in G. depressus (in fact, it appears only very sligthly concave in Saussure’s figures), whereas it is clearly notched on the lateral margin in J. lagostoma (see Türkay 1970: fig. 5 c, as Gecarcinus (Johngarthia) lagostoma). Young (1900: 240, as Geocarcinus depressus) provided a description based on Saussure and considered the species valid. In any case, the species Gecarcinus depressus deserves close scrutiny. According to Hollier (2018: 294; see also Hollier & Hollier 2012), two small male syntypes of Gecarcinus depressus from Haiti, first dry then transferred into alcohol, are deposited at the MHNG. The two specimens are stored in separate tubes in the same jar, with two typewritten labels indicating that Türkay revised the specimens in 1972 and identified them as G. lateralis lateralis (Türkay 1970: 337). But a careful examination of the photographs of these two syntypes (one male 19 × 23 mm, another one damaged), kindly sent by J. Hollier, poses a problem: the two syntypes belong to two different species. Specimen MHNG-ARTO- 16403, a male c. 23.1 × 18.7 mm (Fig. 8 A-D) is not G. lateralis but is quite similar to G. ruricola in that the mesial lobe of the infraorbital margin is overlapped by the frontal edge (versus only joined in G. lateralis); the mxp 3 merus (somewhat asymmetric) is oval and rather close to the front, with an unnotched anterior margin and a barely notched internal margin (versus anterior border emarginated in G. lateralis); and the tip of the male sterno-pleonal cavity extends to the thoracic sternal suture 2 / 3 (versus the two are distant in G. lateralis). The small exorbital tooth present (Fig. 5) is also found in our smallest specimens of G. ruricola from Haiti (Fig. 6 C). These characters are rather those of G. ruricola. Although the mxp 3 merus of G. depressus (Fig. 8 C) is not as narrow distally and not as obliquely directed as in our Haitian G. ruricola specimens (Fig. 6 A-C), even in the smallest examined (Fig. 6 C), it remains quite distinct from that of G. lateralis (under its former name, see below under Harnollius lateralis n. comb. (Figs 10 B; 11 B; 12 A, B). Given the variations observed in the G. ruricola examined, it is possible that G. depressus is pro parte a young G. ruricola. Conversely, specimen MHNG-ARTO- 16404, a male c. 17.6 × 14.6 mm, with a damaged carapace, has the mesial lobe of the infraorbital margin just joining the frontal margin (Fig. 8 E, F); the right mxp 3, in place, is smaller, very far from the front; the merus is small, its anterior margin is slightly subnotched whereas its internal margin is slightly bowed; the left mxp 3, detached and photographed at higher magnification, shows a clear notch on the anterior margin (Fig. 8 F, H). This is the specimen whose Saussure (1858 a: 439, pl. 2 fig. 14, a-c; 1858 b: 23, fig. 11) depicted the mxp 3 in the same way on several occasions, and which, in this respect, most resembles G. lateralis (under its former name; see under Hartnollius lateralis n. comb.), although studied and compared by Saussure on the same page. If genomic sequencing were to demonstrate the existence of genetically distinct populations in Haiti (simple working hypothesis), the specific name depressus could apply. See above, Phenotypic variations.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481643FFF0BD1B596346C0FC6A.taxon	description	(Figs 5, 9; 10 B, C, E, F; 11 B, C; 12 - 16; 19; 20; Table 1) urn: lsid: zoobank. org: act: 1 AA 58 DB 8 - 96 B 4 - 45 DF-B 4 E 8 - 31 FF 0 AB 827 C 4 RESTRICTED CHRESONYMY All previous mentions of Gecarcinus species in the literature that do not refer to G. ruricola according to the diagnosis above should be designated as Hartnollius n. gen. The list below only contains the references related to Gecarcinus sensu lato (unless they concern G. ruricola) and / or to one or other of the species reported to it, i. e., G. lateralis, G. quadratus and G. nobilii, which should henceforth be known as Hartnollius lateralis n. comb., H. nobilii n. comb. and H. quadratus n. comb. The chresonymy presented below in the form of a list has been restricted in view of the numerous taxonomic articles published on Gecarcinidae and also those dealing with the numerous aspects of land crabs (ecological, behavioural, embryological, physiological, biological). We did not take into account the species of Gecarcinus attributed to Johngarthia before its establishment by Türkay (1970).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481643FFF0BD1B596346C0FC6A.taxon	materials_examined	TYPE SPECIES BY PRESENT DESIGNATION. — Gecarcinus lateralis Fréminville in Guérin, 1832 (see Low et al. 2013: 104; N. K. Ng et al. 2019: 99). OTHER INCLUDED SPECIES. — Gecarcinus quadratus Saussure, 1853; G. nobilii Perger & Wall, 2014.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481643FFF0BD1B596346C0FC6A.taxon	etymology	ETYMOLOGY. — Named in honour of Richard G. Hartnoll, who provided several important and valuable works on the Gecarcinidae, particularly on their biology, and notably on Gecarcinus ruricola. Furthermore, and not least, Richard has been, from the beginnings until today, a source of inspiration for the first author, who wishes to express her immense admiration for him. Gender masculine.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481643FFF0BD1B596346C0FC6A.taxon	diagnosis	DIAGNOSIS Carapace Carapace broader than long, flat, with hepatic, subhepatic and branchial regions not markedly inflated, widest part of carapace being more or less in line with antero-lateral angles of mesogastric region. Fronto-orbital distance about half of maximum carapace width in adults. Dorsal surface with shallow grooves: cervical groove terminating anteriorly in a pit near orbital angle; median (or urogastric) groove well-defined but shallow; longitudinal mesogastric groove well-defined but shallow, rising towards frontal margin. Numerous striae along lateral margins of the carapace, used as stridulatory pars stridens. Front short, moderately produced and deflexed, with straight lateral margins and upturned lower margin. Mesial lobe of infraorbital margin angular, just joining front edge, completely exposed. Antero-lateral margins rounded, not delimitated in males; marked by granular margin in females. Cephalic structures Antennules very small, folded obliquely. Antennae very short, completely exposed. Orbits typical, outer angle marked. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome covered by subfrontal plate, thus not visible. Epistome developed, with one median crest and a lateral crest on each side. Buccal cavity rhomboid. Subhepatic and pterygostomial region glabrous, with many striae. Mxp 3 Mxp 3 rather small, not reaching epistome (except in H. quadratus n. comb.), leaving between them a narrow rhomboid gap, in which mandibles are exposed. Ischium in longitudinal position and merus only slightly obliquely directed, their articulation nearly horizontal. Ischium barely smaller than merus, without longitudinal groove (only a small trace); merus directed slightly obliquely, with anterior margin emarginate but variably, sometimes only slightly, barely concave (H. quadratus n. comb.) or with distinct notch; meri of both sides not joining medially (except in H. quadratus n. comb.); palp inserted below merus: its first article fused to merus internal surface and with only small portion of last mobile article exposed. Exopod of mxp 3 completely concealed, apex not reaching ischium-merus articulation, as narrow suboval plate; without flagellum. Chelipeds Male chelipeds massive but not extraordinarily enlarged, very unequal, especially in old males; heterochely and heterodonty usually not or only slightly marked; in rare cases of greatly uneven chelipeds (heterochelic chelae), a more pronounced gap and pronounced heterodonty. No genetic predisposition for right-handedness. Merus smooth (H. lateralis n. comb.) or with only small granules on inner lower margin (H. quadratus n. comb., H. nobilii n. comb.); carpus smooth (H. lateralis n. comb., H. quadratus n. comb.) or with denticles (H. nobilii n. comb.) on inner upper margin; occlusal margins of fingers with small, spaced teeth on both sides. Sexual dimorphism moderate. Ambulatory legs P 3 moderately spiny. Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines. Dactylus with four rows of small equal spines (H. lateralis n. comb., H. nobilii n. comb.) or with six rows of small unequal spines (H. quadratus n. comb.). Sterno-pleonal cavity and pleon Sterno-pleonal cavity moderately setose, short, not close to thoracic sternal suture 2 / 3, with marked ridge around telson. Male pleon moderately long, with all somites free plus telson; somite 6 with more or less convex lateral margins. Margins of pleon only with fringe of setae. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, narrowing at level of somite 5, thus restricted at level of P 1. Sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate with convex margins; suture 2 / 3 present, practically straight or barely concave, in open V-shaped (H. lateralis n. comb.); suture 3 / 4 absent, without lateral trace; sternites 3 + 4 completely fused, with gently concave or nearly straight margins; sutures 4 / 5 to 7 / 8 interrupted; sternites 5 - 7 similarly shaped, sutures well defined; suture 7 / 8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7 at level of narrow median bridge at level of suture 7 / 8; another weak median bridge at level of suture 6 / 7 (H. lateralis n. comb., H. quadratus n. comb.); deep median line only along sternite 7. Locking pleonal structure as prominence rather close to suture 4 / 5, covered by setae; pleonal sockets not delineated, so pleonal locking no longer functional. Patches of more or less dense hydrophilic setae located along first pleonal somites margins of pleon and at its junction with carapace. Male gonopore and penis Male gonopore and penis at level of suture 7 / 8 emerging rather far from P 5 coxo-sternal condyle. G 1 and G 2 G 1 slightly tapering at its extremity, with unequal setae at its tip; apex short; laterally, a very long, narrow, horny, more or less curved tube, not folded and open all along, and exceeding G 1 tip; several horny setae at its base. G 2 very small, without flagellum. Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481641FFCBB8265F414390FC8B.taxon	description	(Figs 5; 9 A; 10 B, E; 11 B; 12; 13 A, B; 16; 19; Table 1)	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481641FFCBB8265F414390FC8B.taxon	materials_examined	TYPE MATERIAL. — Neotype (designation by N. K. Ng et al. 2019: fig. 2 F). Guadeloupe • ♂ 36.7 × 47.2 mm; dry ;; Beaupertuis coll.; as Gecarcinus lateralis; MNHN-IU- 2000 - 3758 (= MNHN-B 3758). OTHER MATERIAL EXAMINED — Guadeloupe • 1 ♂ (DAMAGED), 1 ♀ 23.9 × 27.6 mm; dry; M. Beaupertuis coll.; as Gecarcinus lateralis; MNHN-IU- 2000 - 3757 (= MNHN-B 3757) • 22 ♂ 40.5 × 55.7 mm (photo), 40.4 × 54.3 mm, 32.8 × 40.7 mm, 32.6 × 41.6 mm, 30.0 × 36.6 mm, 28.0 × 35.0 mm, 25.9 mm, 32.7 mm, 24.7 × 30.6 mm, 22.2 × 27.4 mm, 21.4 × 26.0 mm, 21.0 × 26.2 mm, 20.5 × 24.7 mm, 18.5 × 22.6 mm, 15.8 × 18.8 mm, 15.3 × 18.7 mm, 16.7 × 20.6 mm, 16.5 × 20.3 mm, 13.2 × 15.8 mm, 13.0 × 15.7 mm, 12.0 × 14.8 mm, 11.8 × 13.8 mm; 12 ♀: 32.6 × 41.8 mm (photo), 27.5 × 34.2 mm, 27.4 × 35.4 mm, 26.4 × 33.0 mm, 22.4 × 27.7 mm, 20.4 × 25.7 mm, 17.9 × 21.6 mm, 17.6 × 21.7 mm, 16.2 × 19.7 mm, 13.4 × 16.4 mm, 13.2 × 16.3 mm; in ethanol; Côte sud de Grande Terre, Anse Vinaigri, Stn 131; Muséum Antilles 1978; 9. VI. 1978; as Gecarcinus lateralis; MNHN-IU- 2017 - 8390 (= MNHN-B 24656) • 1 ♂ 28.2 × 36.3 mm; Îles des Saintes, Terre-de-Haut; KARUBENTHOS 3; Stn IGM 1; 15 ° 52.6 ’ N, 61 ° 34.7 ’ W; 8. X. 2024; MNHNARBig-LPRig coll.; MNHN-IU- 2024 - 5132 • 1 ♀ 29.3 × 35.9 mm; Guadeloupe, Marie-Galante; KARUBENTHOS 3, Stn IGM 25, 15 ° 53.3 ’ N, 61 ° 13.3 ’ W; 16. X. 2024; MNHN-ARBig-LPRig coll.; MNHN-IU- 2024 - 5551. Martinique • 1 ♂ 27.8 × 34.6 mm; dry; M. Bélanger; as Gecarcinus lateralis; MNHN-IU- 2000 - 10768 (= MNHN-B 10768) • 1 ♂ 28.8 × 35.5, 1 ♀ 28.0 × 35.0; dry; M. Bélanger; as Gecarcinus lateralis; MNHN-IU- 2000 - 3755 (= MNHN-B 3755) • 1 ♂ cl 26.2 ca damaged; dry; as Gecarcinus lateralis; MNHN-IU- 2000 - 3756 (= MNHN-B 3756). Cayman Islands, Little Cayman • 1 ♂ 29.0 mm × 37.0 mm, Cayman Expedition, 1938; in bush and plantation; Coll. Oxford University, 1952; 1.17.4 - 6; det. Gecarcinus ruricola; NHM. Bahamas • 1 ♂ 43.6 × 57.4 mm; dry; as Gecarcinus ruricola; MNHNIU- 2000 - 10933 (= MNHN-B 10933). Panama • 1 ♂ 44.7 × 56.7 mm; Naos Island; Panama Survey; 4. V. 1971; C. A. Child, det Gecarcinus ruricola; USNM 155253. Gulf of Mexico, Florida • 2 ♂ 31.0 × 39.9 mm, 32.3 × 40.5 mm, 2 ♀ 38.3 × 47.2 mm, 31.6 × 38.8 mm; Florida Keys; Loggerhead Key, N. End; 30. VII. 1926; Rathbun det. Gecarcinus ruricola; USNM 71219. (See Fig. 5 A, B). Nicaragua • 2 ♂ 32.4 × 44.2 mm, 31.0 × 40.3 mm, Greytown, Rathbun det. Gecarcinus ruricola; label by Carson: “ looks like to me G. lateralis ”; 25. X. 1965; Barnwell det. G. lateralis, 14 VIII. 1975; USNM 74612. (See Fig. 5 C, D). French Guiana • 1 specimen 18.0 × 23. mm (damaged); dry; M. Leprieur; as Gecarcinus lateralis; MNHN-IU- 2000 - 3754 (= MNHNB 3754). Mexico • 1 ♂ 43.0 × 55.0 mm; in ethanol; Playa Isla Blanca, Quintana Roo; 21. VII. 2018; as Gecarcinus lateralis; CNCR 35126. TYPE LOCALITY. — Guadeloupe (see N. K. Ng et al. 2019: 99, 100).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481641FFCBB8265F414390FC8B.taxon	diagnosis	DIAGNOSIS Carapace Carapace of smaller size than Gecarcinus ruricola, broader than long but proportionally less broad than G. ruricola, relatively flat, with hepatic, subhepatic and branchial regions not markedly inflated; widest part of carapace being in line with antero-lateral angles of mesogastric region. Fronto-orbital distance about half or a little less than half of maximum carapace width in adults. Dorsal surface with shallow grooves: cervical groove ending anteriorly in a pit near orbital angle; median (or urogastric) groove and longitudinal mesogastric groove rising towards frontal margin. Numerous striae along lateral margins of the carapace, used as stridulatory pars stridens. Front short, broad, moderately produced and deflexed, widening very little below, its inferior margin being slightly arcuate. Mesial lobe of infraorbital margin angular, just joining front edge and completely exposed. Antero-lateral margins entire, not markedly rounded, joining exorbital angle, with more or less marked junction; marked by granular row in females. Cephalic structures Antennules very small, folded obliquely. Antennae very short, completely exposed. Orbits small, with marked angle at anterolateral margin. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome covered by subfrontal plate. Epistome developed, with one median crest and a lateral crest on each side, setose. Buccal cavity rhomboid. Subhepatic and pterygostomial region glabrous, with many striae. Mxp 3 Mxp 3 rather small, not reaching epistome, leaving between them a narrow rhomboid gap, in longitudinal position. Ischium and merus subequal, with their articulation only slightly oblique; ischium barely smaller than merus, without longitudinal groove (only a small trace); merus only slightly directed obliquely, not narrowing anteriorly; anterior margin with slight but distinct emargination, sometimes only concave and with barely marked notch; meri of both sides not joining medially; palp inserted below merus: palp with first article fused to merus internal surface and with mobile distal article barely exposed. Exopod of mxp 3 as narrow plate, completely concealed by fringe of thick setae, apex not reaching ischium-merus articulation; without flagellum. Chelipeds Male chelipeds massive but not extraordinarily enlarged, very unequal especially in old males, widely gaping; heterochely variable, usually slightly marked; occlusal margins of fingers with small, spaced teeth on both sides; in the rare cases of greatly uneven chelipeds (heterochely), a more pronounced gap and pronounced heterodonty. Merus and carpus of adults without row of granules, entirely smooth or may be with two spiniform granules; young adults with two rows of teeth on merus and spiniform granules on inner margin of carpus. Inner surface of palm of chelae used as stridulatory plectrum by rubbing on pterygostomial striae (pars stridens). Female chelipeds subequal or nearly so, moderately gaping, therefore sexual dimorphism moderate. Ambulatory legs P 3 moderately spiny. Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines. Dactylus with four rows of small equal spines. Sterno-pleonal cavity and pleon Sterno-pleonal cavity completely glabrous, short, ending far from sternal suture 2 / 3, with marked ridge around telson. Male pleon moderately long, bell-shaped; with all somites free plus telson; lateral margins with fringe of setae; somite 6 with convex lateral margins, forming lateral shoulder; telson campanulate, narrower than somite 6, with lateral margins slightly marked, tip rounded, relatively narrow. Female pleon subcircular; telson forming isosceles triangle, as wide as or slightly narrower than posterior margin of somite 6, lateral margins straight, smooth. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, narrowing at level of somite 5, thus restricted at level of P 1; sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate, with strongly convex margins; suture 2 / 3 present, practically straight or barely concave and only forming an obtuse angle; suture 3 / 4 absent, without lateral trace; sternites 3 + 4 completely fused, with concave, obliquely directed margins; sutures 4 / 5 to 7 / 8 interrupted; sternites 5 - 7 similarly shaped, sutures well defined; suture 7 / 8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7; at level of suture 7 / 8 only some traces of bridges; deep median line only along sternite 7. Locking pleonal structure as prominence covered by setae, rather close to suture 4 / 5; corresponding pleonal sockets not delineated, so pleonal locking no longer functional (Guinot & Bouchard 1998: 660, 685; Köhnk et al. 2017: 2212). Setal tufts of more or less dense hydrophilic setae located along first pleonal somites, margins of pleon and at its junction with carapace. Male gonopore and penis Male gonopore and penis at level of suture 7 / 8 emerging rather far from P 5 coxo-sternal condyle. G 1 and G 2 G 1 slightly tapering at its extremity, apex short, with unequal setae at its end; laterally, a very long, narrow, horny, unfolded and curved tube, open over a long length and exceeding G 1 tip; several horny setae at its base. G 2 very small, without flagellum. Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum. COLOUR Based on Gecarcinus lateralis from Bermuda described by Verrill (1908: 308), Rathbun (1918: 356) wrote: “ Commonly the carapace is mostly of a deep reddish brown or plum color; often this color is replaced posteriorly by a wide transverse band of lighter color spotted with yellow; this band extends forward, along each side, becoming narrower and darker, disappearing near the eye-sockets; a pair of small white spots close behind the eye-sockets and another pair in the cardiac region; legs light grayish brown; chelipeds darker and more red; last joint bright orange, underside white. ” See also Chace & Hobbs (1969: 198, figs 5 A-C, 6 A-C, 7, 8, as G. lateralis); Parasram et al. (2021: fig. 8, as G. lateralis) (Fig. 19). According to Perger & Wall (2014: 105, table 2), the colour of the Pacific Gecarcinus lateralis they examined showed little variation (see their figs 5 A, 7 E-F, 8 G, H) and did not approach the range of variability found in G. lateralis from the Atlantic coast of Central America, characterised by morphs with transitional forms (see their figs 5 B, C, 7 A-D, 8 A-F). For a detailed study of the colour variation in G. lateralis from Bimini, Bahamas, and from the Bermudas, see Martinez & Bliss (1989: figs 1 - 12, pls 1 - 3, as G. lateralis). VERNACULAR NAMES ‘ Black land-crab’, ‘ common land-crab’ (Rathbun 1918); ‘ black-backed land crab‘ in Saint Martin (Yokoyama 2013). Also called ‘ Tourloulou’ or ‘ Touloulou’, like other species of Gecarcinidae, including Gecarcinus ruricola.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481641FFCBB8265F414390FC8B.taxon	discussion	REMARKS The authorship of Gecarcinus lateralis is traditionally attributed to Fréminville (1835) (e. g. H. Milne Edwards 1837 a; Chace & Hobbs 1969; Türkay 1970; Bliss et al. 1978; Hartnoll et al. 2006 a, b; Ng & Guinot 2001; Ng et al. 2008; Perger & Wall 2014). Low et al. (2013) stated that Guérin (1832 in Guérin 1829 - 1837) should have priority. Fréminville (1835) described Ocypoda lateralis from Guadeloupe and its islands (Les Saintes, Marie-Galante, La Désirade), and Martinique in the West Indies, based on specimens he probably collected himself. In the introduction to this paper (1835: 213, footnote), the editor of the volume, namely H. Milne Edwards, indicates about Fréminville’s ‘ tourlourou’: “ son Ocypoda lateralis est une espèce de Gécarcin bien distincte et dont j’ai donné une figure dans mon Histoire naturelle des Crustacés. M. Guérin l’a également figurée dans son Iconographie du règne animal. ” [“ his Ocypoda lateralis is a clearly distinct species of ‘ Gecarcin’ and to which I have given a figure in my Histoire naturelle des Crustacés. M. Guérin has also figured it in his Iconographie du règne animal ”]. Guérin (1832, in Guérin 1829 - 1837: 7) had previously used the name “ Gecarcinus lateralis Fréminville ” and illustrated what is clearly the same species. It is very likely that Guérin used the same material as Fréminville and that he was aware of the future species by Fréminville. According to the official dates, Guérin’s plate has been published before the description by Fréminville in 1835. According to Low et al. (2013), the authorship of G. lateralis must be credited to Guérin (1832). But, as Fréminville is solely responsible for the species name in a way satisfying the criteria of availability (Code, Art. 50.1.1), the authorship of G. lateralis should be credited to Fréminville in Guérin (1832) (see N. K. Ng et al. 2019). As explained by N. K. Ng et al. (2019: 100), Türkay (1970), based on erroneous indications given by J. Forest, the curator of Crustacea Collection in the MNHN at the time, regarded as the type series of Gecarcinus lateralis material collected by two French naturalists, Beaupertuis and Bélanger, and deposited in this institution. That is why Türkay (1970: 337) selected as lectotype of Gecarcinus (Gecarcinus) lateralis a specimen from Guadeloupe collected by Beaupertuis, MNHN-IU- 2000 - 3758 (= MNHN-B 3758). Türkay (1974: 974, 975, fig. 2) then designated as paralectotypes one male and one female from Guadeloupe, MNHN-IU- 2000 - 3757 (= MNHN-B 3757), and two males and one female collected by Bélanger from Martinique, MNHN-IU- 2000 - 3755 (= MNHN-B 3755), MNHNIU- 2000 - 3756 (= MNHN-B 3756). A colour figure of this lectotype was published by Perger & Wall (2014: fig. 6 AC). However, Beaupertuis’ and Bélanger’s specimens were probably not collected during this period (i. e., before 1832), these two naturalists having travelled in the Antilles later on, as shown by the entry dates of their material in the CAA (Beaupertuis: 1839 from Guadeloupe; Bélanger: 1859, 1860, 1864 from Martinique), and cannot constitute the original material seen by Guérin (1832). The specimen from Guadeloupe previously referred to, although unsupported, as the lectotype of this species by Türkay (1970), then by Perger & Wall (2014), registered MNHN-IU- 2000 - 3758 (= MNHN-B 3758) and eligible for neotype designation, was selected as the neotype of G. lateralis by N. K. Ng et al. (2019: 99, fig. 2 F). Türkay (1974: 974, fig. 2, as G. lateralis) found that the mxp 3 showed a high degree of variability in the shape of the merus emargination, and this even in the type series where it may be different in each side. GEOGRAPHICAL DISTRIBUTION	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
423782481641FFCBB8265F414390FC8B.taxon	biology_ecology	BIOLOGY Several important contrasts between Gecarcinus ruricola and Hartnollius lateralis n. comb. are treated under the first (see above). H. lateralis n. comb. is more common than G. ruricola, often found 6 - 9 m above high-tide mark but sometimes up to 1000 m from shore, and is largely herbivorous, but also opportunistic carnivore and cannibal (Wolcott & Wolcott 1984; 1988: fig. 3.3.9; Burggren & McMahon 1988: fig. 3.6). According to studies on Hartnollius lateralis n. comb. carried out by Bliss et al. (1978: figs 6, 7 - 11, 13 - 31, as Gecarcinus lateralis) at Sabal Point, just north of Boca Raton Inlet, Florida, with environmental conditions supporting a dense population of H. lateralis n. comb., the crabs can be seen outside of their burrows during the daytime, an unusual behaviour for this species that is typically an active burrower. In eastern Florida, H. lateralis n. comb. inhabits wooded areas of dune ridges and back dunes, under logs and leaf litter, and burrows in dry sandy areas; it is primarily nocturnal (Powers 1977: 139). In Martinique, traps to catch the ‘ touloulou’, e. g. ‘ Z’attrap crab’ or ‘ bwèt à krab’, are placed over the holes. Observations on the species in Bermuda by Savazzi (1985: figs 1 A, 2 A, 3 A, B, 4, 5 A, B, as Gecarcinus lateralis; see also Schmalfuss 1978) showed that it excavates permanent tunnels in compacted soil in grass-covered areas or among tree roots and boulders: finely tuberculated terraces on the chelipeds, around the sides of the carapace and on the walking legs, are related to a wedging function (see also Davie et al. 2015 a: fig. 71.2.30 C).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167AFFC8BD6858214044F868.taxon	description	(Figs 9 B; 10 C, F; 11 C; 13 C; 14; 16; 20; Table 1)	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167AFFC8BD6858214044F868.taxon	materials_examined	TYPE MATERIAL. — Syntype. Mexico • 1 ♂ cl 39.7 mm; Mazatlán [M. Verreaux]; ANSP CA 3741. Perhaps another one ♂ syntype of which only a small cheliped is preserved. MATERIAL EXAMINED. — Mexico • 1 ♀ 39.4 × 49.7 mm; dry; Oaxaca; rev. M. Türkay VI. 1972 det. Gecarcinus (Gecarcinus) lateralis; MNHN-IU- 2000 - 3759 (= MNHN-B 3759) • 2 ♀ 40.0 × 51.0 mm, 40.6 × 53.0 mm; dry; MNHN-IU- 2000 - 3761 (= MNHN-B 3761); Gecarcinus quadratus • 1 ♂ 50.0 × 64.0 mm; in ethanol; Estero El Verde Camacho, Sinaloa; 12. VII. 1972, M. Hendrickx det. 1998 Gecarcinus quadratus; MNHN-IU- 2017 - 8391 (= MNHN-B 20900). Unknown location (Gabon?: incorrect location) • 1 ♂ 47.0 × 62.7 mm, 1 ♀ 42.4 × 52.7 mm; dry; M. Verreaux; det. Gecarcinus quadratus; Türkay Rev. VI. 1972 Gecarcinus lateralis; MNHN-IU- 2000 - 3762 (= MNHN-B 3762). TYPE LOCALITY. — Mazatlán (Mexico).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167AFFC8BD6858214044F868.taxon	diagnosis	DIAGNOSIS Carapace Carapace smaller than that of Gecarcinus ruricola but larger than that of Hartnollius lateralis n. comb., broader than long, relatively flat, with hepatic, subhepatic and branchial regions only slightly inflated; widest part of carapace being in line with antero-lateral angles of mesogastric region. Carapace front about as wide as distance between mesial ends of suborbital cristae. Dorsal surface with shallow grooves: cervical groove terminating anteriorly in a pit near orbital angle; median (or urogastric) groove and longitudinal mesogastric groove rising towards frontal margin. Fronto-orbital distance about half or a little less than one half of maximum carapace width in adults. Front short, broad, moderately produced and deflexed, widening very little below, its inferior margin being slightly arcuate. Numerous striae along lateral margins of the carapace, used as stridulatory pars stridens. Mesial lobe of infraorbital margin angular, just joining front edge and completely exposed. Antero-lateral margins entire, rounded, joining exorbital angle, with more or less marked junction, smooth in males; delineated by granular row in females. Cephalic structures Antennules very small, folded obliquely. Antennae very short, completely exposed. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome covered by subfrontal plate. Epistome developed, with one median crest and a lateral crest on each side, setose. Buccal cavity rhomboid. Subhepatic and pterygostomial region glabrous, with many striae. Mxp 3 Mxp 3 rather small, reaching epistome, leaving between them a narrow rhomboid gap, in longitudinal position. Ischium and merus subequal, with their articulation only slightly obliquely directed; ischium barely smaller than merus, without longitudinal groove (only a small trace); merus slightly directed obliquely, anterior margin straight, without distinct emargination, at the very least barely concave, or showing only discontinuity or even having very small notch; meri of both sides practically joining medially; palp inserted below merus: palp with first article fused to merus internal surface and with only small portion of mobile distal article exposed. Exopod of mxp 3 as narrow plate, completely concealed by fringe of thick setae, apex not reaching ischium-merus articulation; without flagellum. Chelipeds Male chelipeds massive but not extraordinarily enlarged, very unequal especially in largest males, not widely gaping; heterochely variable, usually slightly marked; occlusal margins of fingers with small, spaced teeth on both sides; in case of greatly heterochely, pronounced heterodonty. In adults, merus with only small granules and carpus smooth on inner lower margin. Inner surface of palm of chelae used as stridulatory plectrum by rubbing on pterygostomial striae (pars stridens). Female chelipeds subequal or nearly so, moderately gaping, therefore sexual dimorphism moderate. Ambulatory legs P 3 moderately spiny. Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines. Dactylus with six rows of small unequal spines, with 5 rows in juveniles. Sterno-pleonal cavity and pleon Sterno-pleonal cavity moderately setose, short, not close to sternal suture 2 / 3, with marked ridge around telson. Male pleon moderately long, bell-shaped; with all somites free plus telson; lateral margins only with fringe of setae; somite 6 with gently convex lateral margins, forming lateral shoulder; telson equilateral triangle-shaped, narrower than posterior margin of somite 6, lateral margins slightly concave. Female pleon subcircular; telson forming isosceles triangle, as wide as or slightly narrower than posterior margin of somite 6, lateral margins straight, smooth. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, narrowing at level of somite 5, thus restricted at level of P 1; sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate, with slightly convex margins; suture 2 / 3 present, practically straight or barely concave and only forming an obtuse angle; suture 3 / 4 absent, without lateral trace; sternites 3 + 4 completely fused, with concave margin at level of articulation of P 1 and convex at junction of mxp 3; sutures 4 / 5 to 7 / 8 interrupted; sternites 5 - 7 similarly shaped, sutures well defined; suture 7 / 8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7; at level of narrow median bridge at level of suture 7 / 8; deep median line only along sternite 7. Locking pleonal structure as prominence covered by setae, rather close to suture 4 / 5; corresponding pleonal sockets not delineated, so pleonal locking no longer functional (see also Köhnk et al. 2017: 2112). Setal tufts of more or less dense hydrophilic setae located along first pleonal somites margins of pleon and at its junction with carapace. Male gonopore and penis Male gonopore and penis at level of suture 7 / 8 emerging rather far from P 5 coxo-sternal condyle. G 1 and G 2 G 1 slightly tapering at its extremity, apex short, with unequal setae at its tip; laterally, a very long, narrow, horny, unfolded, curved tube, open over all along and exceeding G 1 tip; several horny setae at its base. G 2 very small, without flagellum. Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum. COLOUR Sex independent colour dimorphism: in males and females, purplish, red, white, with variously coloured spots, intense purple chelipeds and light yellow or orange legs (Fig. 20). For more details, see Perger & Wall (2014: 101, figs 4, 5 D) and Toledano-Carrasco (2019: 24, fig. 10 B).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167AFFC8BD6858214044F868.taxon	discussion	REMARKS According to the original description and figure of G. quadratus by Saussure (1853: 360), there is no notch on the anterior margin of the mxp 3 merus, so that Hartnollius quadratus n. comb. (Fig. 10 C) shares with Gecarcinus ruricola (Fig. 10 A) a slightly similar aspect of this region. In fact, in H. quadratus n. comb., the margin is either straight (Rathbun 1918: fig. 162) or discontinuous, and may even have a small notch. The margin of the mxp 3 merus of a Mexican male specimen MNHN-IU- 2017 - 8391 (= MNHN-B 20900) is asymmetric: straight on one side and very slightly emarginate on the other side (Figs 10 C; 14 A, B). Whereas Rathbun (1918: 358) indicated that the type of Gecarcinus quadratus was in the ‘ Geneva Mus. ’, it was in ’ Phil. Acad’ according to Stimpson (1857: 29). No specimen is found in the MHNG collection (Hollier 2018). Although not in the list of Spamer & Bogan (1994), according to Boyko (2000: 128) there are parts of one male syntype cl 39.7 mm, from Mazatlán, deposited at the ANSP under the number ANSP CA 3741, which contains also a detached male cheliped from perhaps one of two now-lost ANSP specimens. According to Sherman (2002, as Gecarcinus quadratus), in the Costa Rica’s Corcovado National Park, Hartnollius quadratus n. comb. lives in fossorial populations, with up to six crabs per square meter in the coastal forest extending about 600 m inland from the Pacific Ocean. H. quadratus n. comb. affects plant diversity in a Neotropical continental rain forest by selective seedling consumption. According to Griffiths et al. (2007, as Gecarcinus quadratus), in the same location it is an engineering species that controls nutrient cycling in tropical forests: during the dry season, the density of land crab burrows decreases with distance from the ocean, so that H. quadratus n. comb. is restricted to a narrow coastal zone with a sandy substrate; this distribution could have profound effects on plant community structure. GEOGRAPHICAL DISTRIBUTION	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167FFFC3BD7B5BA247A2F868.taxon	description	(Fig. 15; Table 1)	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167FFFC3BD7B5BA247A2F868.taxon	materials_examined	TYPE MATERIAL. — Paratype. Ecuador • ♀ 36.6 × 44.3 mm, in ethanol; St Helena, Festa coll. Original label: “ Gecarcinus Festae Nob. (cotype), Nobili 1901, Muséum Paris ”, Perger & Wall, 2014 det. Gecarcinus nobilii; MNHN-IU- 2014 - 11211 (= MNHN-B 12314). TYPE LOCALITY. — Punta Galera, Ecuador (see Perger & Wall 2014).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167FFFC3BD7B5BA247A2F868.taxon	diagnosis	DIAGNOSIS Carapace Carapace transversely ovate, broader than long, widest in anterior half, relatively flat, with hepatic, subhepatic and branchial regions moderately inflated; widest part of carapace being in line with antero-lateral angles of mesogastric region. Frontal width distinctly wider than distance between the mesial ends of suborbital cristae. Dorsal surface with weakly developed grooves, i. e, cervical, median (or urogastric) and longitudinal mesogastric grooves. Striae along lateral sides of carapace. Front short, broad, moderately produced and deflexed, widening very little below, its inferior margin being slightly arcuate. Mesial lobe of infraorbital margin just joining carapace front edge and completely exposed. Supraorbital margin gently sinuous, with small granules, confluent with anterolateral margin; exorbital tooth weakly developed, tip not over-reaching orbit. Orbital and anterolateral margins marked by row of small granules in males as in females. Anterolateral margins entire, not as rounded, joining exorbital angle, with more or less marked junction. Cephalic structures Antennules very small, folded obliquely. Antennae completely exposed. Eyestalks relatively short, curved. Proepistome, epistome and pterygostome Proepistome covered by subfrontal plate. Epistome rather developed, with one median crest and a lateral crest on each side. Suborbital, subhepatic and pterygostomial regions sparsely granular laterally. Mxp 3 Mxp 3 rather small, not concealing epistome, leaving between them a narrow rhomboid gap, in longitudinal position. Ischium and merus subequal, with their articulation only slightly oblique; ischium without longitudinal groove (only a small trace); anterior margin of merus without distinct emargination, nearly straight, but may be with a slight notch; meri of both sides not joining medially; palp inserted below merus with only distal portion of last mobile article exposed. Exopod of mxp 3 as narrow plate, completely concealed by fringe of thick setae, apex not reaching ischium-merus articulation; without flagellum. Chelipeds Male chelipeds subequal, widely gaping; heterochely and heterodonty usually not or only slightly marked; occlusal margins of fingers with small, spaced teeth on both sides; in the rare cases of greatly uneven chelipeds (heterochely), a more pronounced gap and pronounced heterodonty. Merus with only small granules on inner lower margin; carpus with denticles on inner upper margin. Female chelipeds subequal or nearly so, moderately gaping, therefore sexual dimorphism moderate. Ambulatory legs P 3 moderately spiny. Propodus with unequally developed lateral carinae bearing four rows of weakly developed spines. Dactylus with four rows of small equal spines. Sterno-pleonal cavity and pleon Sterno-pleonal cavity completely glabrous, short, ending far from sternal suture 2 / 3, with marked ridge around telson. Male pleon moderately long, bell-shaped; with all somites free plus telson; lateral margins with fringe of setae; somite 6 with convex lateral margins, forming lateral shoulder; telson campanulate, narrower than somite 6, with lateral margins slightly marked, tip rounded, relatively narrow. Female pleon subcircular; telson forming isosceles triangle, narrower than posterior margin of somite 6, lateral margins straight, smooth. Thoracic sternum, locking pleonal structures and setal tufts Thoracic sternum wide, slightly narrowing at level of somite 5; sternite 1 as small triangular tooth, not separated by suture from sternite 2, not recessed; sternite 2 semi-ovate, with slightly convex margins; suture 2 / 3 present, practically straight or barely concave and only forming an obtuse angle; suture 3 / 4 absent, without lateral trace; sternites 3 + 4 completely fused, with obliquely directed margins slightly convex at junction of mxp 3, almost straight or gently concave at level of articulation of P 1; sutures 4 / 5 to 7 / 8 interrupted; sternites 5 - 7 similarly shaped, sutures well defined; suture 7 / 8 rather short; sternite 8 not developed medially, totally hidden when pleon is folded; posterior emargination reaching sternite 7. Male gonopore and penis Male gonopore and penis at level of suture 7 / 8 emerging rather far from P 5 coxo-sternal condyle. G 1 See Perger & Wall (2014: 101, fig. 2 D-E). Vulvae Protruding, oriented nearly horizontally, normally occluded by rigid calcified immobile operculum. COLOUR Red and white forms in males and females. Light lateral margin on dorsal carapace present, contrasting to dark median pattern, same colour as lateral carapace; some white forms with orange tinge; no orange patch at anterolateral carapace border and at posterior lateral urogastric groove; mesial lobe of infraorbital margin mostly grey; ventro-lateral carapace homogeneously red or white; cheliped palm uniformly red or white (see Perger & Wall 2014: 97, figs 3 with faded colour, 4 A-H, 5 D, table 2).	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
42378248167FFFC3BD7B5BA247A2F868.taxon	discussion	REMARKS The MNHN paratype was collected by Enrico Festa probably during his 1895 - 1898 trip to Ecuador (Viaggio del Dr. Enrico Festa nella Republica dell’Ecuador et regioni vicine), then studied by Nobili, who initially considered it new and dedicated it to Festa under the name “ Gecarcinus festae ” without definitively establishing it. In fact, Nobili never published a description of Gecarcinus festae, which is therefore a nomen nudum. In 1901, Nobili described Sesarma festae and Uca festae, and, in the same article, he referred specimens collected in Ecuador to Gecarcinus ruricola, a species restricted to the western Atlantic islands (Perger & Wall 2014). The MNHN specimen examined by Nobili and selected as the paratype of the new species Gecarcinus nobiili, dedicated to Nobili by Perger & Wall (2014), is shown in their fig. 3 D-F and is deposited at the MNHN (Fig. 15). The holotype is preserved at the LACM (see Perger & Wall 2014: 97; N. K. Ng et al. 2019: 99). GEOGRAPHICAL DISTRIBUTION Ecuador, Colombia and Peru. The specimens of Gecarcinus (Gecarcinus) quadratus from Peru previously reported by Türkay (1970: 338) may belong to Hartnollius nobilii n. comb. (see Perger & Wall 2014). The Gecarcinus ruricola of Cano (1889: 101, 227) from Ecuador must be also assigned to H. nobilii n. comb. PALAEONTOLOGICAL DATA Palaeontological analyses can be informative in assessing the continuity of phenotypes over time and geographical areas, but they are limited by the availability of fossils. Practically nothing is known about fossil or subfossil records from Gecarcinus. Fossil crab chelae attributed to Gecarcinus cf. ruricola reported by Donovan & Dixon (1998: 825) from the Pleistocene of Jamaica were later recognised as belonging to a species of Sesarma Say, 1817 (see Luque 2017; Luque et al. 2017). The Late Holocene remains of Gecarcinus sp. reported from Antigua by Pregill et al. (1988) would be conspecific with Hartnollius lateralis n. comb. (Luque 2017: fig. 1 H-J, table 1, as Gecarcinus lateralis). A Gecarcinus sp. from the late Pleistocene of Bermuda (Crystal Cave) is reported by Luque (2017: table 1). A total of 1400 identifiable Holocene remains of the two co-occurring species G. ruricola and G. lateralis have been found through field surveys along the northern coast of San Salvador Island and in the Bahamas, with various levels of disarticulation suggesting a low preservation potential (Locatelli 2013: 867, figs 2 - 7, table 1). Schweitzer et al. (2023: 2) report G. ruricola from the Holocene in the Caribbean Sea and Mexico. According to Schweitzer et al. (2023) records are very few in gecarcinids. According a molecular phylogeny of Thoracotremata by Tsang et al. (2022: 5), the family Gecarcinidae (with also the Sesarmidae) originated along with the warm climates during the Late Paleocene and Early Eocene (c. 60 - 50 MYA). GENETICS An alignment of 658 base pairs (364 conserved, 139 parsimony-informative and 173 variable) was used for the COI gene and 559 bp (292 conserved, 70 parsimony-informative and 120 variable) for the 16 S gene, resulting in a concatenated matrix of 1217 bp (Table 2). Since the trees generated using Bayesian Inference and Maximum Likelihood displayed the same topology, only the BI tree is shown, with the BI and ML support values. The concatenated tree recovers the two major groups of gecarcinids proposed by Guinot et al. (2018), based on the consistency of morphological, larval and genetic data. On the one hand, the clade of crabs with less terrestrial habits (highlighted in purple) formed by the genera Cardisoma Latreille, 1828, Discoplax A. Milne-Edwards, 1867, and Tuerkayana Guinot, N. K. Ng & Rodríguez Moreno, 2018. On the other hand, the clade of gecarcinids with markedly terrestrial habits (highlighted in red) that includes the genera Gecarcinus, Johngarthia Türkay, 1970 and Hartnollius n. gen. (Fig. 16). Focusing on crabs highly adapted to terrestrial life, which are central to this study, Gecarcinus is identified as the probable sister taxon to Hartnollius n. gen. while in the less terrestrial clade, Discoplax and Tuerkayana form sister groups, collectively maintaining a close evolutionary relationship with Cardisoma (Fig. 16). Individuals of Gecarcinus ruricola from Cuba (ZMHK 65343) and Guadeloupe (MNHN-IU- 2024 - 7258 and MNHN-IU- 2024 - 4640), which morphologically show some differences (position of merus mxp 3 in relation to frontal margin, and position of extremity of sterno-pleonal cavity in relation to thoracic sternal suture 2 / 3), are nested in the same clade with a high branch support (Fig. 16), highlighting that Gecarcinus ruricola is a species with some morphological variability across its distribution range. Pairwise nucleotide divergences for COI with K 2 P distance (Table 3) indicate a high divergence between Gecarcinus and Hartnollius n. gen. (on average 9.56 with H. lateralis n. comb. and 11.14 with H. quadratus n. comb.), values comparable with the divergence between species of different genera such as those of Hartnollius n. gen. and Johngarthia lagostoma (10.62 with H. lateralis n. comb. and 11.40 with H. quadratus n. comb.) and Discoplax longipes with Tuerkayana latens (12.67 %). Notably, the genetic distance between Gecarcinus and Johngarthia is lower than that between Gecarcinus and Hartnollius n. gen. (see Table 3), as previously highlighted by Toledano-Carrasco et al. (2021). All these findings further support the validity of the new genus. The average interspecific divergence between Hartnollius lateralis n. comb. and H. quadratus n. comb. (5.56 %) closely matches the 6.1 % previously reported by Toledano-Carrasco et al. (2021). Genetic divergence between the two individuals of Gecarcinus ruricola (MNHN-IU- 2024 - 7258 and MNHN-IU- 2024 - 4640) from Guadeloupe and the individual from Cuba (ZMHK 65343) is extremely low, almost zero (0.37 %). The genetic distances between individuals of the two subclades of Gecarcinidae are remarkably high, ranging from 17.44 % between Cardisoma guanhumi and Johngarthia lagostoma to 20.58 % average between Discoplax longipes and Gecarcinus ruricola reflecting the high divergence between the two groups.	en	Paula, Danièle Guinot, Rodríguez, Paula A., Atzimba, Moreno I., Toledano-Carrasco, Atzimba (2025): The charismatic Gecarcinus ruricola (Linnaeus, 1758), type species of Gecarcinus Leach, 1814, with a neotype designation and genetic data, and new generic assignment, Hartnollius n. gen., for the three remaining species of the genus (Crustacea, Brachyura, Gecarcinidae). Zoosystema 47 (16): 261-314, DOI: 10.5252/zoosystema2025v47a16, URL: https://sciencepress.mnhn.fr/sites/default/files/articles/pdf/zoosystema2025v47a16.pdf
