Monomia gladiator s. str. (Fabricius, 1798)

Windsor, Amanda M., Mendoza, Jose Christopher E. & Deeds, Jonathan R., 2019, Resolution of the Portunusgladiator species complex: taxonomic status and identity of Monomiagladiator (Fabricius, 1798) and Monomiahaanii (Stimpson, 1858) (Brachyura, Decapoda, Portunidae), ZooKeys 858, pp. 11-43 : 11

Monomia gladiator s. str. (Fabricius, 1798) Figs 1 A–D, 3 A–C, 4 A–D

Portunus gladiator Fabricius, 1798: 368; Latreille 1825: 189; Crosnier 1962 (in part): 51, figs 72, 76, 78, 82, 83, pl. 3 fig. 2; Stephenson and Rees 1967 a: 14; 1967b: 25; 1968: 293 (in part); Stephenson 1972a: 16, 39 (in part); 1972b: 135 (in part); Bhadra 1998: 410; Dev Roy and Bhadra 2005: 425; 2011: 147.

Cancer menestho Herbst, 1803: 34, pl. 55 fig. 3.

Lupea gladiator , H. Milne Edwards 1834: 456.

Neptunus gladiator , A. Milne-Edwards 1861: 330; Richters 1880: 152; Müller 1887: 475; De Man 1888: 69; Henderson 1893: 367.

Neptunus (Amphitrite) gladiator , Miers, 1886: 177; Alcock 1899: 35, 36; Laurie 1906: 412.

Callinectes gladiator , Stebbing 1915: 58. Non Callinectes gladiator Benedict, 1893 (fide Stephenson and Cook 1973).

Monomia gladiator , Barnard 1950: 156; Fourmanoir 1954: 9; Spiridonov et al. 2014: table 1; Trivedi et al. 2018: 66, table 1.

Portunus (Monomia) gladiator , Jeyabaskaran et al. 2000: 51, pl. 36c; Biju Kumar et al. 2007: 286; Ng et al. 2008: 151, 156, 157 (list and discussion).

Portunus (Monomia) gladiator [sic], Krishnamoorthy 2009: 6 (list).

Portunus haanii , Stephenson and Cook 1973: 429 (in part), figs 6 A–E, 7 A–E, 8 A–E, 9A, 10A, C, D, G; Stephenson 1975: 178. Non Amphitrite haanii Stimpson, 1858.

Monomia haanii , Chertoprud et al. 2012: 314, pl. 51 fig. G. Non Amphitrite haanii Stimpson, 1859.

Non Cancer gladiator Fabricius, 1793: 449 (= Portunus sanguinolentus (Herbst, 1783), fide Latreille 1825).

Non Portunus (Amphitrite) gladiator , De Haan 1833: 65; 1835: pl. 18 fig. 1 (= Portunus orbitosinus Rathbun, 1911).

Non Portunus gladiator , Stephenson and Campbell 1959: 110, Figs 2J, 3J, pl. 3 fig. 2, pl. 4 fig. J, pl. 5 fig. J (= Portunus australiensis Stephenson and Cook, 1973).

Material examined.

INDIA: ZRC.2016.0145, 2 males, 1 female, Pazhayar Fish Landing, Nagapattinam District, Tamil Nadu, coll. NK Ng et al., 17 Sep. 2011; ZRC.2016.0149, 1 female, sandy beach, Pondicherry, Union Territory of Puducherry; ZRC.2018.1189, 5 males, Jeppiar Fishing Port, Muttom, Tamil Nadu, coll. PKL Ng et al., 19 Sep. 2016; USNM127069, 1 male, SW of Mumbai, IIOE Anton Bruun, 14 Nov. 1963.

AUSTRALIA: WAM-C26459, 2 males, Dampier Archipelago, Cape Brugieres, Western Australia, coll. Slack-Smith and Hewitt, 17 Jul. 1999; WAM-C61155, 2 females, WAM-C61156, 1 female, Pilbara Shelf, Western Australia, coll. E Morello et al. (CSIRO Pilbara Survey), 13 Jun. 2013.

PENINSULAR MALAYSIA: ZRC.2000.1308, 4 males, Perhentian, coll. anon., 16 May 1976.

MYANMAR: ZRC.2016.0030, 1 female, Ayeyarwady Delta, coll. EAF-Nansen Project (Myanmar cruise), 19 May 2015; ZRC.2016.0034, 1 male, Tanintharyi Coast, coll. EAF-Nansen Project (Myanmar cruise), 26 May 2015.

SINGAPORE: ZRC.1965.10.22.1-2, 1 male, 1 female, Siglap, coll. M.W.F. Tweedie, Jul. 1933; ZRC.1984.338-348, 4 males, 7 females, Horsburgh Lighthouse, South China Sea near Singapore, coll. H Huat, 15 Dec. 1982; ZRC.1984.5451-5453, 3 males, Tuas fishery port, coll. WM Lee, 25 Sep. 1982.

THAILAND: USNM127068, 2 females, Andaman Sea, north of Phuket, IIOE Anton Bruun R/V, 31 July. 1963; ZRC.2000.0779, 3 males, 13 females, Phuket, Pichai Fish Port, coll. NK Ng et al., 17-20 Jan. 2000; ZRC.2000.0842, 2 males, Phuket, Pichai Fish Port (Andaman Sea), coll. PKL Ng et al., 3-6 May 2000; ZRC.2002.0297, 4 males, 1 female, Phuket, Pichai Fish Port, coll. JCY. Lai, 2-3 Sep. 2001; ZRC.2002.0298, 3 males, 1 female, Phuket, Pichai Fish Port, coll. JCY Lai, 2-3 Sep. 2001; ZRC.2003.0114, male, Pattani Fishing Port, Pattani Province; ZRC.2003.0197, 1 male, Saiburi Crab Landing, Pattani Province, coll. Z Jaafar et al., 8 Jun. 2003.

Diagnosis.

Carapace (Fig. 1 A–D) transversally hexagonal, CW/CL ratio 1.79-1.83, with dorsal surface, except patches of granules, densely covered by short tomentum. Regions moderately defined; with discrete patches of granules on gastric, branchial, cardiac and intestinal regions. Front subdivided into four teeth with rounded apices, median pair distinctly smaller than lateral; median sulcus between teeth continuing ventrally to triangular projection appressed to median epistomial tooth. Epistome well defined, median tooth projecting beyond front. Supraorbital margin finely granulate, with two distinct notches; inner orbital angle tooth-like, with glabrous ventromesial ledge. Infraorbital margin with deep, V-shaped notch laterally; in antero-ventral view, mesial part of infraorbital margin granulate, ventrally a large triangular tooth projecting anteriorly, visible from dorsal view. Anterolateral margin armed with nine teeth, including external orbital angle, with granulate margins; first tooth larger than following teeth except 9th, with straight outer margin; 2 nd– 8th subequal in size, sharp, projecting outward, slightly curved anteriorly; 9th tooth largest, projecting laterally; just underneath anterolateral margin is thick coat of long soft setae which sometimes obscures teeth. Posterolateral margin concave, posterolateral angle rounded; posterior margin lined with small granules, straight to slightly convex; posterior margin with ventrally directed, smooth flange, lateral extremities of which coincide with posterolateral angle of carapace, each armed with small, lamelliform tooth.

Basal article of antennule completely filling antennular fossa, subsequent two articles slender. Basal article of antenna short, with broad, lateral projection entering but not obstructing orbital hiatus; flagellum long, exceeding well beyond orbit. Eyes with well-developed corneas, short, thick peduncles. Proepistome well developed, anterior tip with projecting conical tooth; epistome not extensively projecting posteriorly. Endostome with well-developed lateral ridges.

Third maxillipeds finely granulate on ischium, merus and exopod, setose on external surfaces, extensively pilose on mesial margins; ischium longer than wide, subrectangular, with deep, submesial sulcus; merus longer than wide, rhomboidal, anterolateral angle strongly projecting laterally; palp articles subcylindrical. Exopod stout, with subdistal triangular projection on inner medial border; flagellum well developed.

Male thoracic sternites covered with thick tomentum, thickest on exposed surfaces of sternites 5-8 (Fig. 3 A–C); sternites 1-4 distinctly granulate, with granules becoming larger, coarser in large specimens; sternites 1, 2 fused, separated from sternite 3 by straight suture; sternites 3, 4 almost completely fused except for remnants of suture at lateral extremities, replaced mesially by smooth, setose groove; sternite 4 with narrow median groove on exposed surface, continuing posteriorly into sterno-pleonal cavity. Sutures 4/5, 5/6, and 6/7 present on exposed surface of thoracic sternum but interrupted within sterno-pleonal cavity; suture 7/8 present on most of exposed thoracic sternal surface, but disappearing just before sternopleonal cavity. Median longitudinal line evident at level of sternites 6, 7, 8, absent elsewhere. Press-button tubercle of sternopleonal locking mechanism located on posteromesial projection of sternite 5.

Chelipeds (P1), long, robust, surfaces tomentose; slightly heterochelous, major chela usually with modified cutting/crushing tooth proximally on cutting margin of dactylus. Merus long, with 4, sometimes 5, curved spines along flexor margin, and 2 distal spines on extensor margin; both margins densely setose. Carpus with sharp spine on inner angle, and flattened spine on external surface continuing as a strong carina, with additional, shorter carina above it. Dorsal surface of palm (propodus) with two straight, longitudinal granular crests, inner one distally ending distally in strong spine; small proximal spiniform tooth at articulation with carpus; two additional, curved granular crests on external surface of palm, first ending at level of articulation with dactylus, second, lower, ending near gape, creating cristate, proximo-ventral margin of palm; inner surface of palm with two wide, distinct rows of granules. Fingers generally straight except for curved, pointed tips; subequal in length to palm; with two granulate crests each on external and internal surfaces; lowest carina on fixed finger extending into palm; numerous teeth on cutting margins, arranged in groups so that each group has large central tooth flanked by smaller teeth of decreasing size, giving the cutting margins appearance of having three or more denticulate, triangular lobes.

First to third ambulatory legs (P2-P4), long, slender; decreasing in length and size, with P2 largest, P4 smallest; flexor margins of meri, carpi, propodi and dactyli heavily setose. Fifth ambulatory (natatory) leg (P5) with quadrate merus, pentagonal carpus, flat, subrectangular propodus, and flat, oval dactylus; margins of articles regularly setose; propodus with four raised glabrous longitudinal bands, including flexor and extensor margins, interspersed with tomentum; dactylus with five raised glabrous bands, including flexor and extensor margins, interspersed with tomentum, distal third with low median crest continuing proximally as narrow tomentose stripe; in fresh specimens, P5 propodus with white band on postero-distal margin, no purple spot, P5 dactylus with small white spot on distal end.

Male pleon (Fig. 3 A–C) 'inverted T’ -shaped, external surfaces mostly tomentose, 3 rd– 5th pleomeres fused. First pleomere very thin, less wide, mostly obscured by flange of posterior margin of carapace. Second pleomere much wider than first, lateral edges resting on P5 coxa, with prominent transverse keel running along entire width. Third pleomere widest, formed like a wedge, visible from both dorsal and ventral view; strong transverse crest somewhat forming posterior margin of cephalothorax, with shallow notch medially, posterolateral angles sharp, acute; sulcus between fused 3rd and 4th pleomere moderately deep, glabrous. Fourth pleomere subrectangular, wider than long, lateral margins convex, central region with low transverse crest. Fifth pleomere subtrapezoidal, basal margin wider than anterior. Sixth pleomere subrectangular; median length about 1.2 times maximum width; width at maximum lateral convexity greater than basal width; anterior margin concave, basal margin straight, lateral margins convex anteriorly, concave posteriorly. Telson subtriangular, apex rounded, lateral margins slightly concave, basal margin convex; median length 1.2 times basal width, with rounded tip, broadly rounded posterior margin.

G1 (Figs 4 A–D) with proximal half relatively wide, somewhat flattened, strongly bent medially, by at least 45° but much less than 90°, distal half very slender, filiform; apically slightly recurved, rounded; distal tip much narrowed to small unarmed aperture. G2 about half length of G1, slender, distal tip minutely bilobed. Penis long, slender, uncalcified; emerging from sternocoxal condyle of P5.

Remarks.

Following the recognition of Monomia Gistel, 1848, as a genus distinct from Portunus Weber, 1795 (see Mantelatto and Robles 2007; Mantelatto et al. 2009; Schubart and Reuschel 2009; Chertoprud et al. 2012; Spiridonov et al. 2014), the taxonomy of its type species, Monomia gladiator (Fabricius, 1798), needs to be assessed.

Firstly, there are five specimens identified as syntypes of Portunus gladiator Fabricius, 1798, in the Zoological Museum of the University of Copenhagen (ZMUC) (see http://www.zmuc.dk/inverweb/invertebrater/Crustacea%20databases/Fabricius%20collection.htm). All are dry specimens with the catalog numbers ZMUC-CRU 4704 through 4708 (see Ng et al. 2008). Examination of their photographs (available online) show that one of them is clearly not conspecific nor even congeneric (viz. ZMUC-CRU 4707). Accompanying this specimen in the photograph is a handwritten label identifying it as " Achelous Whitei A. M. Edw.," a name now considered a junior synonym of Lupocycloporus gracilimanus (Stimpson, 1858) (viz. Ng et al. 2008), a widespread species known from several localities in the Indo-West Pacific region; and a check with the available literature (e.g., Stimpson, 1907: pl. 10 fig. 3) confirms this identification. To stabilize the taxonomy of Portunus gladiator Fabricius, 1798, one of the other four syntypes, a male ZMUC-CRU 4705 (Fig. 1A), is hereby designated as the lectotype, and the other three specimens (ZMUC-CRU 4704, 4706 and 4708) become paralectotypes.

Secondly, we agree with Ng et al. (2008) that there is no secondary homonymy between Portunus gladiator Fabricius, 1798, and Cancer gladiator Fabricius, 1793, because the two species were originally described in different genera, and the name "Cancer gladiator Fabricius, 1793" is no longer available by virtue of its synonymization under Portunus sanguinolentus (Herbst, 1783) (viz. Latreille 1825; Stephenson and Cook 1973). Although Chertoprud et al. (2012) cite the use of the name " Portunus gladiator (Fabricius, 1793)" by Stephenson and Cook (1973) as meeting the requirement of Article 59.1 of the Code, we view this as a misinterpretation of the Code’s provisions for homonymy. Furthermore, with the recognition of Monomia Gistel, 1848, as a full genus, thus absolutely eliminating any reservations concerning secondary homonymy, the species name Monomia gladiator (Fabricius, 1798) is, therefore, valid.

Thirdly, there is the matter of the confusion between M. gladiator and M. haanii . Stephenson and Cook (1973) proposed Amphitrite haanii Stimpson, 1858, as a replacement name for P. gladiator Fabricius, 1798, and this has led to the current confusion between the two names. As the following discussion will show, it is evident that Monomia gladiator and M. haanii (Stimpson, 1858) are distinct and valid species, and, therefore, the latter cannot be used as a replacement name for the former.

Monomia gladiator differs from M. haanii primarily in these three morphological characters: (1) in the fresh specimens of M. gladiator , there is a white band on the postero-distal margin of the P5 propodus, but no purple spot, and a small white spot on the distal tip of the P5 dactylus (Fig. 1C, D; also Chertoprud et al. 2012: pl. 51 fig. G) (vs. in M. haanii , there is a large purple spot on the distal tip of the P5 propodus, and the distal one-third of the P5 dactylus is colored purple; Fig. 1E, F; also Sakai, 1939: pl. 47 fig. 3; 1965: pl. 57, fig. 1; Chertoprud et al. 2012: pl. 51 fig. H); (2) the anterolateral margins of the male 6th pleomere are more flared out and rounded in M. gladiator , and at their widest extent exceed the basal width of the 6th pleomere (Fig. 3 A–C; also Stephenson and Cook, 1973: fig.10A) (vs. straight, convergent anteriorly, and separated from concave posterolateral margin by an angular convexity in M. haanii , widest at base, Figs 2B, 3 D–F); and (3) the G1 is bent at an angle of about 45° at mid-length and the distal tip is slender and relatively narrower in M. gladiator (Fig. 4 A–D) (vs. G1 bent at or almost at 90°, and distal tip is somewhat wider than the immediate subdistal region in M. haanii (Figs 2C, 3 E–H). Aside from these are some minor differences; for instance, the mesial part of the infraorbital margin of M. gladiator is granulate and there is no tooth on the mesial end as it abuts the basal article of the antenna, there is, however, a large tooth immediately ventral to this margin, which projects outward and is visible from dorsal view as if it were part of the infraorbital margin. In M. haanii , the mesial end of the infraorbital margin has a large tooth which abuts against the basal article of the antenna. Also, the spines on the flexor margin of the P1 merus of M. gladiator tend to be more projecting and recurved than those of M. haanii , which are relatively smaller and less curved. Examination of available fresh-color photographs (viz. Chertoprud et al. 2012: pl. 51 Figs G, H) also show that these meral spines tend to be entirely white in M. gladiator while they are red at the base and white at the tips in M. haanii .

Furthermore, the molecular phylogenetic analysis corroborates the morphological evidence, clearly showing two distinct and well-supported clades corresponding to the two species. Specimens identified as M. gladiator based on the characters described above, including a topotypic specimen from India (ZRC.2016.0149), form a well-supported clade distinct from another clade containing specimens with the morphological attributes of M. haanii , which also includes a topotypic specimen from Japan (ZRC.2000.0084). Furthermore, the same molecular phylogenetic analysis shows that the specimen referred to by Chertoprud et al. (2012) as " Monomia haanii " (JX398095) falls within the M. gladiator clade, whereas the specimen referred to by Chertoprud et al. (2012) as " Monomia pseudoargentata " (JX398094) falls within the M. haanii clade. These specimens should now be identified as M. gladiator and M. haanii , respectively.

Finally, Lupea gladiator H. Milne Edwards, 1834 (Indian Ocean), is re-included in the synonymy of Monomia gladiator (Fabricius, 1898), and Cancer menestho Herbst, 1803 (probably from Indian Ocean) is hereby considered a junior subjective synonym of Monomia gladiator (Fabricius, 1798). We believe that Stephenson and Cook (1973) erred in removing these two names from the synonymy of gladiator sensu Fabricius, 1798. In the case of H. Milne Edwards’ specimen, the error is due simply to their conflation of haanii with gladiator . In the case of Herbst’s species, we disagree with them that the illustration of Cancer menestho does not show 2 spines on the posterior margin of the cheliped merus. What they call a “non-protruding” spine is an artifact of perspective. We have seen in our photographs of M. gladiator , that this second spine can appear non-protruding when the merus is viewed from directly above and if the marginal setae obscure its entire outline. Once this so-called difference is eliminated, there is no compelling reason why C. menestho should also not be treated as a synonym of M. gladiator .