Joeranina, Van Bakel & Guinot & Artal & Fraaije & Jagt, 2012

Van Bakel, Barry W. M., Guinot, Danièle, Artal, Pedro, Fraaije, René H. B. & Jagt, John W. M., 2012, A revision of the Palaeocorystoidea and the phylogeny of raninoidian crabs (Crustacea, Decapoda, Brachyura, Podotremata) 3215, Zootaxa 3215 (1), pp. 1-216 : 36-37

Genus Joeranina n. gen.

Type species. Corystes broderipii Mantell, 1844 , by present designation.

Diagnosis. Carapace small, subhexagonally elongated in outline, dorsal surface fairly convex in cross section, nearly flat longitudinally; maximum width at level of base of epibranchial spine; weak axial carina may be discerned; orbits large, front relatively narrow, bifid, with 2 distal, 2 subdistal spines; frontal process of mesobranchial region bounded by deep furrows, usually diverging backwards; anterolateral margins short, arched, with single ( Joeranina broderipii n. comb., J. platys n. comb.) or 2 spines ( J. gaspari n. sp., J. syriaca n. comb.) at level of hepatic region, in addition to single epibranchial spine; posterolateral margins long, with small spine behind subtle branchial notch, rimmed, may be finely denticulate; dorsal regions moderately well-defined by shallow grooves; cervical groove well defined, markedly thin, continuous, relatively deep; protogastric region defined by admedial, triangular protuberance directed forwards; hepatic lobe elongated, inclined, with small, acute suborbital protuberance directed forwards; deep frontal furrows mark the anterior mesogastric process, slightly constricted at level of epigastric regions,, extend onto rostrum; posterior half of carapace usually non-areolated. Pterygostome large, with blunt crests, buccal margin concave, with broad buccal collar. Mxp3 markedly elongated, in oxystomian condition, coxae large, flabelliform, basis-ischium long, narrow, smooth, clearly separated by fissures. Abdomen narrow, entirely covering sternal space laterally in both sexes, reaching sternite 4; all somites free, somites 1, 2 restricted for P5 coxae, somites 1, 2 medially raised, somites 3, 4 with medial tubercle, somites 5, 6 medially raised, telson rounded triangular ( J. broderipii ). Thoracic sternum narrow; sternites 1, 2 narrow, pointed; sternite 3 inverted trapezoidal; deep lateral incision separating sternites 3, 4; sternite 4 trapezoidal, anterior corners sharp; distal portion of episternite extending laterally; sternite 5 with short, arched, lateral depressions; episternite 5 triangular, with distinct double peg for abdominal holding; sternite 6 with deep lateral depressions; sternites 7, 8 oblique, spermathecal aperture elongated. P1 homochelous, margins spinose; P2‒P4 with merus, propodus, dactylus flattened; P5 reduced, subdorsal. Dorsal surface with pits and/or fine granules, mostly on axial keel and laterally.

Derivation of name. In honour of J.S.H. Collins (London), a prolific author, for his contributions to our knowledge of the Palaeocorystidae .

Species included. Joeranina broderipii ( Mantell, 1844) [as Corystes ], J. gaspari n. sp., J. harveyi ( Woodward, 1896) [as Palaeocorystes ], J. japonica ( Jimbô, 1894) [as Eucorystes japonicus ], J. paututensis ( Collins & Wienberg Rasmussen, 1992) [as Notopocorystes (Cretacoranina) ], J. platys ( Schweitzer & Feldmann, 2002b) [as Eucorystes ] and J. syriaca ( Withers, 1928) [as Notopocorystes syriacus ].

Material examined. Joeranina broderipii: MAB k. 2892 (female), carapace with thoracic sternum and pereiopods, MAB k. 2894 (indeterminate sex), dorsal carapace, MAB k. 2913 (female), carapace with thoracic sternum showing spermathecal aperture, MAB k. 2915 (female), carapace with thoracic sternum and appendages, Albian, Escalles (Calais, northern France); MAB k. 2896 (indeterminate sex), carapace with thoracic sternum and bases of pereiopods, MAB k. 2879 (ex B. Fraaije Collection, female), carapace with thoracic sternum and bases of pereiopods, NHM In. 31313 (indeterminate sex), carapace with well-preserved sternum, pterygostomes and abdomen, MNHN-B.14177, 2 specimens, NHM In. 21331 (indeterminate sex), carapace with sternum and pterygostomes, NHM In. 59796 (indeterminate sex), well-preserved carapace with legs and chelipeds, NHM In. 31312 (indeterminate sex), well-preserved carapace with partial appendages, Albian, Folkestone (Kent, southern England); NHM In. 61147 (lectotype, male), carapace with well-preserved sternum and abdomen, NHM In. 29810-11 (indeterminate sex), partial carapace with well-preserved frontal area, NHM In. 61148-49 (paralectotypes, indeterminate sex), carapace with partial sternum, middle or upper Albian, Ringmer, Sussex, southern England. J. gaspari n. sp.: type series, see below. J. syriaca ( Withers, 1928) : holotype, NHM I.8407, Upper Cretaceous,?Cenomanian, Mt. Lebanon, Syria. Joeranina sp. : MNHN F.R03930, fragmentary carapace with associated remains of sternum, pterygostome and mxp3, Cenomanian, Antsirane, Madagascar (illustrated by Van Straelen 1931: 56, pl. 2, fig. 39).

Remarks. Joeranina n. gen. comprises species that had previously been assigned to either Cretacoranina , Eucorystes or Notopocorystes . The new genus is unique in the following features: anterior mesogastric process marked by deep, long frontal furrows, usually constricted between undefined epigastric regions; post-frontal terrace absent, only small hepatic and admedial protogastric protuberances; cervical groove complete, well-defined, also laterally, medial portion U-shaped; entire axial carina present, may be subtle to rather well-defined, raised; cuticle microstructure with granules and pits.

Cretacoranina emend. differs from other genera of Palaeocorystidae in having a smooth dorsal surface, without (gastric and hepatic) protuberances; in having much shorter frontal furrows, which are limited to the rostrum; absence of a cervical groove and a longitudinal dorsal carina; dorsal carapace with fungiform nodes as cuticle microstructure, rather than pits and granules; and thoracic sternite 4 is anteriorly much wider. Members of Cretacoranina emend. attain much larger sizes.

Eucorystes emend. differs from other palaeocorystid genera in having raised dorsal strap-like lobes, by undulation of the cuticle; the anterior mesogastric process bounded by parallel, shallow furrows, the dorsal surface covered by denser, larger granules, or fungiform nodes. Species of Joeranina n. gen. were sometimes assigned to Eucorystes depending on the interpretation of the dorsal strap-like ornament; however, this is not homologous to the raised structures in Eucorystes emend. (see also remarks under Eucorystes ).

Notopocorystes differs in having a much more convex dorsal carapace, a smaller orbitofrontal width, regions vaulted and tuberculate, the axial carina denticulate, thoracic sternites 1 and 2 on a lower level than sternite 3, and episternite 4 much less well developed. The cervical groove in Notopocorystes is similar in shape, but relatively less marked.

Ferroranina n. gen. is considered most closely related to Joeranina n. gen.; differences are discussed above. As noted by Wright & Collins (1972: 83), relationships amongst the different genera of palaeocorystids are so close that several dorsal elements are shared in the same location but with a distinct appearance in each genus (see Relationships of palaeocorystid genera below). The newly available material examined has permitted distinguishing details of the characters mentioned above.

Joeranina broderipii n. comb. ( Fig. 11A, B, D ) was considered a member of Cretacoranina by Collins (1997: 81) and Tucker (1998: 334). The species is included here in Joeranina n. gen. on the basis of having a short frontal ridge bounded by deep, divergent grooves; inclined hepatic and protogastric tubercles; thin, deep, complete cervical groove and on features of cuticle microstructure. Waugh et al. (2009: 32) confirmed, on cuticular structure (dorsal surface covered by pits and fine granules), that J. broderipii and J. syriaca should be excluded from Cretacoranina emend. Joeranina n. gen., Ferroranina n. gen. and Cretacoranina Mertin, 1941 , are differentiated in Table 3.

Joeranina japonica n. comb. was included in Notopocorystes by Collins et al. (1993: 300), Tucker (1998: table 3) and Yazdi et al. (2009: 74). However, it lacks tubercular regions, a tubercular axial carina and is not as tumid as Notopocorystes spp. It is here assigned to Joeranina n. gen. on the basis of the characteristic forwardly directed hepatic and admedial protogastric protuberances, thin, continuous and rather deep cervical groove, and deep and thin frontal furrows diverging backwards.

Joeranina platys n. comb. was included in Eucorystes ( Schweitzer & Feldmann 2002b) , based on a single, moderately preserved carapace. Better-preserved material ( Schweitzer et al. 2009b: figs. 7, 8) confirms the absence of raised, strap-like lobes; the presence of clear hepatic and admedial protogastric tubercles; clear frontal furrows and a distinct, deep cervical groove. The oblique medial depression on the epibranchial region, also present in Eucorystes as a noticeable strap-like lobe, could cause confusion (see also remarks for Eucorystes ).

Joeranina paututensis n. comb. is considered closely related to J. broderipii , J. harveyi and J. syriacus ( Collins & Wienberg Rasmussen 1992: 31) . The thin and deep cervical groove, the divergent frontal furrows, the triangular and forwardly directed admedial protogastric protuberance, together with the oblique epibranchial grooves, permits placement in the new genus. The species is characterised by the exceptionally narrow rostrum and the welldefined gastric regions.

The only known specimen of Notopocorystes syriacus is fragmentary and lacks the orbitofrontal margin and posterior carapace portion. Tucker (1998: table 4) included N. syriacus in Cretacoranina , but Waugh et al. (2009: 32) stated that, based on cuticle microstructures, the species could not be accommodated in that genus. It is assigned here to Joeranina n. gen. Another fragmentary specimen ( Van Straelen 1931: pl. 2, fig. 39, as Notopocorystes sp. ) (see Fig. 10D, E ), can be tentatively included in Joeranina n. gen. on the basis of the smooth carapace surface, with distinct, rounded, granular axial carina. Some ventral characters are preserved in Van Straelen’s specimen: mxp3 coxa large, granular; basis-ischium long, flattened, smooth, without axial depression.

The assignment of the above-listed species to a new genus leads to a more stable subdivision of Palaeocorystidae and makes typical features of the various genera to be more constant. The new genus is considered here more derived than either Eucorystes or Notopocorystes by showing a less areolated carapace, with a tendency to develop a smoother dorsal surface, a loss of dorsal convexity and the presence of a wider orbitofrontal margin.

Joeranina n. gen. ranges from the lower Albian to the lower Campanian, being widely distributed with records from Europe ( England, France, Spain, Switzerland) to North America ( U.S.A., Canada), Greenland, Syria, Japan and Madagascar. It is commonly found in association with Notopocorystes spp.

Figures

FIGURE 10. Palaeocorystids from Madagascar; A, B, Cretacoranina denisae (Secretan, 1964), lower Campanian, Ampolipoly-Antsirasira region; (A; paratype, labelled Notopocorystes australis Secretan, 1964; MNHN R03878) and MNHN R03875 (B; holotype); C, F, Notopocorystes bituberculatus Secretan, 1964, MNHN R03951 (holotype), Albian, Malandriandro, dorsal view of carapace, and ventral view showing thoracic sternum; D, E, Joeranina sp., MNHN R03930 (indeterminate sex), Cenomanian, Antsirane, dorsal view of fragmentary carapace and ventral view; G, H, Ferroranina australis (Secretan, 1964) n. comb., MNHN R03874 (G; holotype), lower Campanian, Berere, dorsal view of carapace, and MNHN R03903 (H; paratype), lower Campanian, Ampolipoly-Antsirasira, dorsal view of carapace. Scale bars: 5mm.

FIGURE 11. A, B, D, Joeranina broderipii (Mantell, 1844) n. comb. (Palaeocorystidae); A, MAB k. 2894 (indeterminate sex), Albian, Escalles (Calais, northern France), dorsal view of carapace; B, MAB k. 2879 (female), Albian, Folkestone (Kent, southern England), ventral view showing thoracic sternum and bases of pereiopods; D, MAB k. 2915 (female), Albian, Escalles (Calais, northern France), ventral view showing thoracic sternum and appendages; C, E, F, Joeranina gaspari n. sp., Albian, Irurtzun (Navarra, northern Spain), MGSB75296b (C; paratype), dorsal view of anterior portion of carapace; MGSB75296a (E; paratype), dorsal view of carapace, and MGSB75296c (F; paratype), ventral view showing posterior portion of thoracic sternum. Scale bars: 5mm.