Hymenosomatoidea, MacLeay, 1838

GUINOT, DANIÈLE, TAVARES, MARCOS & CASTRO, PETER, 2013, Significance of the sexual openings and supplementary structures on the phylogeny of brachyuran crabs (Crustacea, Decapoda, Brachyura), with new nomina for higher-ranked podotreme taxa, Zootaxa 3665 (1), pp. 1-414 : 224-225

Affinities between Hymenosomatoidea and Inachoididae

The Inachoididae Dana, 1851 , studied by Drach & Guinot (1982, 1983), was hypothesised as closely related to Hymenosomatidae by Guinot & Richer de Forges (1997), who based their conclusion on similarities between the two families.

The main inachoidid features are: (1) flattening of the body, particularly in Leurocyclus , Paradasygyius and Paulita , and, not so extreme, however, as in Hymenosomatidae ; (2) expansion of pleurites 5–8 beyond each side of the carapace, their exposed latero-external parts being calcified and ornamented in the same way as the carapace ( Fig. 47G ; see for example species of Euprognatha Stimpson, 1871 , figured by Santana & Tavares 2008); (3) insertion of the carapace into a gutter (gouttière de sertissage of Drach & Guinot 1982: 716; 1983: 38), which marks the separation between the covered internal portion of the pleurites 5–8 and their uncovered latero-external portion; (4) integration of the first abdominal somite into the cephalothorax; (5) absence of a true branchiostegite; (6) a thoracic sternum/pterygostome junction at the sternite 4 level, which varies from incomplete to complete, with intermediate states and sternal extensions posterior to each pereopod, from P1 to P4; (7) the broad thoracic sternum displaying pattern 5, subpattern 5e, with a median line along sternites 7, 8, and a raised median plate on sternite 7 connecting to the thick sella turcica ( Fig. 56K ) (see Thoracic sternum in the Eubrachyura; Evolution of the thoracic sternum in the Eubrachyura and its patterns); (8) short, only lateral but deep thoracic sternal suture 3/ 4, which ends as a perforation of the sternal surface, and sutures 4/5–7/8 interrupted; (9) male abdomen with all somites free except for somite 6, which is fused with the telson (pleotelson); (10) male gonopore opening far from suture 7/8, in a posteriormost location ( Figs. 31D , 50C, E ); (11) female abdomen having, as in the male abdomen, a maximum of six elements, somites 5 and 6 being fused to the telson (pleotelson), with the formation of a large, discoid plate in ovigerous females ( Guinot & Richer de Forges 1997: figs. 11E, 12E); (12) development of a brood cavity limited by a high sternal ridge, closed like a box, the abdominal margin being tightly joined to its edge, thus the need of a branchiosternal canal for the oxygenation of the eggs; (13) axial skeleton with pleurites almost horizontal, regularly connecting medially, and fused to the carapace by pillars ( Fig. 47H, I ) so that it is difficult to detach the carapace without breaking it (see Evolution of the axial skeleton in the Eubrachyura and its patterns). A true branchiostegite posterior to P2 is absent in Inachoididae .

The gymnopleurity of Inachoididae , with a dorsal exposure, calcification, and ornamentation of pleurites 5– 8 as parts of the carapace, is totally different from that of Raninoidea . The laterally exposed thoracic pleurites 5–7 in the Raninoidea ( Fig. 38B, C ) are a consequence of a lifting of the carapace (a specialisation for burying), thus extending the body’s depth, and form a specialised plate for the respiratory current.

Different states of the thoracic sternum/pterygostome junction are found in Inachoididae depending on the extension of sternite 4. Consequently, the Milne Edwards opening is variously shaped, the developed mxp3 coxa being differently exposed ( Figs. 48A , 49C, E ). The junction is incomplete, e.g., in Paradasygyius depressus , Collodes leptocheles , Pyromaia tuberculata , and Leurocyclus Rathbun, 1897 , whereas it is complete, with entirely separated Milne Edwards openings, in other species, e.g., Paulita tuberculata , Batrachonotus fragosus Stimpson, 1871 , Arachnopsis filipes Stimpson, 1871 , Euprognatha rastellifera Stimpson, 1871 , E. bifida Rathbun, 1893 , and Anasimus latus ( Guinot & Richer de Forges 1997: 488, figs. 11C, 12C, D, 13A, B, 14A, B; Guinot 2012).

The inachoidid sternum is connected to the carapace by sternal extensions between the P1 and P2; moreover, there are extensions between the P2 and P3, P3 and P4, and P4 and P5, extensions that connect the sternum to the laterally exposed pleurites 5–8 ( Drach & Guinot 1982: 720, figs. 1, 3–5; 1983: figs. 1–6; Guinot 1984b: fig. 1, pl. 1, figs. A, B, D, pl. 2, figs. A, C; Guinot & Richer de Forges 1997: fig. 13C). Such sternal extensions do not exist in Hymenosomatoidea , where the interlocking of the carapace with the cephalothorax is considerably modified.

The axial skeleton of the Inachoididae ( Fig. 47G – I ), with both a dorsoventral partition and a lateral compartment, is similar to that of Hymenosomatidae . Additionally, vertical pillars in the anterior region connect the axial skeleton (i.e., the dorsal edges of the pleurites) to the internal surface of the carapace in taxa with a flattened carapace (e.g., Leurocyclus , Paradasygyius and Paulita ), and as well as in those with a thicker body (e.g., Anasimus , Collodes ). This “fusion” is an exceptional disposition in Brachyura ( Drach & Guinot 1982: figs. 5, 6; 1983: figs. 4, 7, 8; Guinot 1984b: 380). Such a pleurites/carapace fusion is absent in Hymenosomatoidea , where the flattening of the body characterising most genera is the most extreme condition known among the Brachyura . The dorippid and inachoidid dispositions are features that have not evolved convergently but have most probably been inherited from a close common ancestor. The hymenosomatoid and inachoidid peculiarities cannot be considered homoplasic, because such important similarities are part of a common groundplan.

The numerous similarities between Inachoididae, Hymenosomatoidea, and Dorippoidea are being interpreted here as a synapomorphy relation (and not a homoplasy relation). This hypothesis is supported by other traits. The gonopore of Inachoididae is coxal as in some (although few) dorippids ( Fig. 15 ), in contrast to the coxosternal condition of the more derived Dorippoidea ( Figs. 16 – 23 ) and the peculiar condition of all Hymenosomatoidea ( Fig. 29A, B ). The inachoidid gonopore opens, however, far from suture 7/8, thus in a posteriormost location, a strong similarity with hymenosomatoids (see Modalities of penis protection: “ sternitreme” protection). The gutter inside of which the carapace lies and involving pleurites 5–7 in Dorippoidea ( Figs. 46A, B , 47A, B ) and the gutter involving pleurites 5–8 in Inachoididae are both reminiscent of the “hymenosomian rim”. Whether this reflects common descent more than convergence needs to be still investigated. The uniform G1 of Inachoididae corresponds to a plesiomorphic state: rather straight, simple, with a slender tip, often with a subterminal lobe ( Garth 1958: pl. B, figs. 8, 9, pl. E, figs. 1–7, 9; Williams 1984: fig. 241b, c, e–g, i, m, n). It is comparable to that of Odiomarinae (basal Hymenosomatoidea ) ( Guinot 2011a) and some Dorippidae . The G2 is very short in Hymenosomatoidea and Inachoididae , whereas it is longer than the G 1 in Dorippoidea .

Deep grooves are often present on the dorsal surface of the carapace in Inachoididae , which are reminiscent of the deep grooves in Dorippidae , resembling a “human face”. For example, the carapace of Paulita is somewhat similar to that of a dorippid. The parallel grooves that deeply cut the carapace dorsal surface of P. tuberculata ( Lemos de Castro 1949: figs. 8–11; Takeda & Okutani 1983: fig. p. 133) perhaps mirror an original metamery, thus denoting a plesiomorphic condition.

Figures

FIGURE 15. Coxal condition in Dorippidae. A–D, Medorippe lanata (Linnaeus, 1767), male 26.0 × 32.0 mm, Senegal (MNHN-B21493): A, genital region; B, penis, G1, G2 in situ; C, G2; D, G1 apex, setae not shown. E, Phyllodorippe armata (Miers, 1881), male 20.0 × 25.0 mm, Dahomey (=Benin) (MNHN-B16380): genital region. a1, abdominal somite 1; b, sclerotised bulb; ba, basipodite; c, coxo-sternal condyle; ca, carapace; co, coxopodite; cx4, cx5, P4, P5 coxae; en, endopodite; e7, episternite 7; G1, G2, gonopods 1, 2; pa, papilla; t, sclerotised tube; 7, 8, thoracic sternites 7, 8; 7/8, thoracic sternal suture 7/8. Outline of the abdomen indicated by dotted line. Scale bars: 5 mm (A, E); 2 mm (B, C); 1 mm (D).

FIGURE 16. Coxo-sternal condition in Dorippidae. Dorippe quadridens (Fabricius, 1793), male 33.0 × 33.5 mm, Vietnam (MNHN-B11177): A, genital region; B, genital region with penis exposed (distal half of penis not shown in its normal vertical position); C, G1, penis, G2 in situ; D, G1 apex; E, G2. a1, abdominal somite 1; b, sclerotised bulb; c, coxo-sternal condyle; ca, carapace; cx4, cx5, P4, P5 coxae; G1, G2, gonopods 1, 2; en, endopodite; pa, papilla; t, sclerotised tube; td, distal portion of penial tube; tp, inclined proximal portion of penial tube; 7, 8, thoracic sternites 7, 8; 6/7, 7/8, sternal sutures 6/7, 7/8. Scale bars: 5 mm (A–C); 1 mm (D); 2 mm (E).

FIGURE 17. Coxo-sternal condition in Dorippidae. A, B, Dorippe tenuipes Chen, 1980. A, male 21.0 × 25.0 mm, South China Sea (MNHN-B8937). B, male 19.0 × 20.0 mm, holotype of Dorippe miersi Serène, 1982, Vietnam (MNHN-B7279): A, genital region covered by abdomen; B, genital region uncovered by abdomen, penis covered by sternite 8. C, Paradorippe granulata (De Haan, 1841), male 11.0 × 11.0 mm, Japan (MNHN-B11181): genital region. D, Philippidorippe philippinensis Chen, 1985, male 25.0 × 30.0 mm, Philippines (MNHN-B18913): genital region covered by abdomen. a1–a3, abdominal somites 1–3; b, sclerotised bulb; c, coxo-sternal condyle; ca, carapace; cx4, cx5, P4, P5 coxae; e7, episternite 7; pa, papilla; td, distal portion of penial tube; tp, inclined proximal portion of penial tube; 6–8, thoracic sternites 6–8; 6/7, 7/8, sternal sutures 6/7, 7/8. Scale bars: 5 mm (A, D); 3 mm (B, C).

FIGURE 18. Coxo-sternal condition in Dorippidae. Dorippoides facchino (Herbst, 1785), male 25.0 × 31.0 mm, India, Pondichery (MNHN-B11178): A, genital region; B, genital region with penis exposed; C, penis, G1, G2 in situ; D, G1 apex. a1, a2, abdominal somites 1, 2; b, sclerotised bulb; ba, basipodite; c, coxo-sternal condyle; ca, carapace; co, coxopodite; cx4, cx5, P4, P5 coxae; en, endopodite; e7, episternite 7; G1, G2, gonopods 1, 2; pa, papilla; td, distal portion of penial tube; tp, inclined proximal portion of penial tube; 7, 8, thoracic sternites 7, 8; 6/7, 7/8, sternal sutures 6/7, 7/8. Outline of the abdomen indicated by dotted line. Scale bars: 5 mm (A); 2 mm (B); 3 mm (C); 1 mm (D).

FIGURE 19. Coxo-sternal condition in Dorippidae. A, B. Dorippoides nudipes Manning & Holthuis, 1986, male 18.0 × 20.0 mm, Madagascar (MNHN-B18276): A, genital region covered by abdomen; B, genital region with penis exposed. C, Neodorippe callida (Fabricius, 1798), male 12.0 × 12.0 mm, China, Amoy (MNHN-11170): genital region. a1, a2, abdominal somites 1, 2; b, sclerotised bulb; c, coxo-sternal condyle; ca, carapace; cx4, cx5, P4, P5 coxae; e7, episternite 7; pa, papilla; t, sclerotised tube; td, distal portion of penial tube; tp, inclined proximal portion of penial tube; 7, 8, thoracic sternites 7, 8; 6/7, 7/ 8, sternal sutures 6/7, 7/8. Scale bars: 5 mm (A, B); 2 mm (C).

FIGURE 20. Coxo-sternal condition in Ethusidae. Ethusa mascarone (Herbst, 1785), male 11.0 × 9.8 mm, Senegal (MNHN- B20933). A, genital region; B, P5 coxa, penis, G1, G2 in situ; C, G1 apex; D, G2. a1, abdominal somite 1; ba, basipodite; c, coxo-sternal condyle; ca, carapace; co, coxopodite; cx4, cx5, P4, P5 coxae; en, endopodite; G1, G2, gonopods 1, 2; p, penis; pa, papilla; 6–8, thoracic sternites 6–8; 6/7, 7/8, thoracic sternal sutures 6/7, 7/8. Outline of the abdomen indicated by dotted line. Scale bars: 2 mm (A, B, D); 1 mm (C).

FIGURE 21. Coxo-sternal condition in Ethusidae. A, Ethusina talismani A. Milne-Edwards & Bouvier, 1897, male 7.0 × 6.0 mm, lectotype, Azores (MNHN-B24049): genital region (proximal portion of penis not shown). B, Ethusa rosacea A. Milne- Edwards & Bouvier, 1897, male 12.0 × 11.0 mm, syntype, off Canary Is. (MNHN-B13545): genital region. C, Ethusa dilatidens Chen, 1997, male 18.0 × 18.0 mm, Philippines (MNHN-B18930): penis with papilla protruding from funnel-like structure. a1, abdominal somite 1; c, coxo-sternal condyle; cx4, cx5, P4, P5 coxae; f, funnel; pa, papilla; t, sclerotised tube; 6– 8, thoracic sternites 6–8; 6/7, 7/8, thoracic sternal sutures 6/7, 7/8. Scale bars: 1 mm (A); 3 mm (B); 1 mm (C). 6–8, thoracic sternites 6–8

FIGURE 22. Coxo-sternal condition in Ethusidae. Ethusina abyssicola Smith, 1884, male 12.6 × 11.0 mm, Massachusetts (MNHN-B24048): A, genital region; B, genital region with penis exposed by dissection; C, P5 coxa, penis, G1, and G2 in situ; D, G1 apex. a1, a2, abdominal somites 1, 2; c, coxo-sternal condyle; ca, carapace; cx4, cx5, P4, P5 coxae; en, endopodite; G1, G2, gonopods 1, 2; p, penis; pa, papilla; 7, 8, thoracic sternites 7, 8; 6/7, 7/8, thoracic sternal sutures 6/7, 7/8. Outline of

FIGURE 23. Sternal male gonopores in Thoracotremata. A, Cardisoma carnifex (Herbst, 1796) (Gecarcinidae), male, Madagascar (MNHN-B29589); B, Plagusia depressa (Fabricius, 1775) (Plagusiidae), male 40.0 × 44.0 mm, Senegal (MNHN- B11693): schematic view (see Fig. 33A) (abdomen indicated by dotted line); C, Ucides cordatus (Linnaeus, 1763) (Ucididae), male 70.0 × 93.0 mm, Brazil (MNHN-B13237) (abdomen indicated by dotted line); D, Grapsus grapsus (Linnaeus, 1758) (Grapsidae), male 57.0 × 60.0 mm, Clipperton I. (MNHN-B11538): schematic representation after dissection; E, F, Ocypode cursor (Linnaeus, 1758) (Ocypodidae), male 38.0 × 49.0 m, Senegal (MNHN): E, before dissection along dotted line; F, after dissection showing ejaculatory duct perforating somite 8, instead of P5 coxa. c, P5 coxo-sternal condyle; cx5, P5 coxa; e.d., ejaculatory duct; e7, episternite 7; g, gonopore; p, penis; p5, pereopod 5; 7, 8, sternites 7, 8; 7/8, thoracic sternal suture 7/8.

FIGURE 29. Male gonopore (A, B) and dorsal platelets of the abdomen (C–E) in Hymenosomatidae. A, Cancrocaeca xenomorpha Ng, 1991, male 3.9 × 4.6 mm, paratype, Indonesia, Sulawesi (MNHN-B24450); B, Odiomaris pilosus (A. Milne- Edwards, 1873) (Odiomarinae), male 20.0 × 22.6 mm, New Caledonia (MNHN-B26146); C–E, same data as B: abdomen in dorsal and ventral views; notice on pleotelson (somite 6 fused to telson) the vestigial uropod as intercalated, dorsal platelet, with socket situated beneath, and uropod (D) with electron microscope (all after Guinot & Richer de Forges 1997: figs. 5B–D, 9A, B). a.c., sterno-abdominal cavity; cx5, P5 coxa; g, gonopore; G1, first gonopod; p, uropod as dorsal platelet; pt, pleotelson; s, socket; 6–8, thoracic sternites 6–8; 6/7, 7/8, thoracic sternal sutures 6/7, 7/8. Scale bar: 100µm (E).

FIGURE 31. A–D. Condylar protection: penis within P5 coxo-sternal condyle. A, Orithyia sinica (Linnaeus, 1771) (Orithyiidae), male 80.0 × 74.0 mm, North China Sea (MNHN-B11612); B, Sayamia germaini (Rathbun, 1902) (Parathelphusidae), male 35.9 × 44.0 mm, holotype of Potamon (Parathelphusa) germaini, Vietnam (MNHN-B5162): penis emerging from extremity of long condyle; C, Leurocyclus tuberculosus (H. Milne Edwards & Lucas, 1842) (Inachoididae), male 33.6 × 36.8 mm, Urugay (MNHN-B9366); D, Stenorhynchus lanceolatus (Brullé, 1837) (Inachoididae), male 34.0 × 16.0 mm, West Africa (MNHN-B21437). E. Non-condylar protection in Dilocarcinus pagei pagei Stimpson, 1861 (Trichodactylidae), male 40.0 × 50.0 mm, Bolivia (MNHN-B12813): penis, with thick sheath, emerging from oblique superior border of condyle. F. Vestigial pleopods on male abdominal somite 5 of Orithyia sinica, same data as in A. a5, a6, abdominal somites 5, 6; c, coxo-sternal condyle; cx5, coxa of P5; e7, episternite 7; G1, first gonopod; I, prominence of sternite 8; m.l., median line; p, penis; pa, papilla; t, sclerotised sheath; te, telson, v, vestigial pleopod; 6–8, thoracic sternites 6–8; 7/8, thoracic sternal suture 7/8. Scale bars: 5 mm (A, F); 1 mm (partial enlargement of A).

FIGURE 38. Non-gymnopleurity in extinct †Palaeocorystoidea (A) in contrast to gymnopleurity in Raninoidea, in extant (B, C) as well as fossil (A) species. A, †Ferroranina dichrous (Stenzel, 1945) (†Palaeocorystoidea †Palaeocorystidae), height of image 48 mm, Middle Cretaceous (Cenomanian-Turonian), Eagle Ford group, Texas: branchiostegite in contact with the coxae; B, Lyreidus tridentatus De Haan, 1841 (Raninoidea, Lyreididae), male 37.1 × 20.7 mm, Philippines (MNHN-B13364): exposed pleurites 5–7 forming flat plate; C, Ranina ranina (Linnaeus, 1758) (Raninoidea Raninidae), female 85.8 × 73.1 mm, Madagascar, Tulear (MNHN-B31983): exposed pleurites 5–7 as excavated plate, dorsally surrounded by P5. a, abdomen; b, branchiostegite; c, carapace; cx, coxa of pereopod; P1–P5, pereopods 1–5; 5–7, exposed pleurites 5–7. Scale bars: 5 mm (B, C). (A, courtesy of B. van Bakel).

FIGURE 46. Axial skeleton of Medorippe lanata (Linnaeus, 1767) (Dorippidae), male, Mediterranean Sea (MNHN). A, carapace (partially removed) covering all pleurites except exposed lateral portions of pleurites 5–7; B, detail of lateroposterior region of carapace to show exposed, calcified external portion of pleurites 5–7, with setting gutter for carapace; thick line indicates carapace border; C, skeleton with endosternites, median plate, and sella turcica. a1, first abdominal somite; b, sclerotised penial bulb; c, carapace edge; ce, ventral extension of carapace posterior edge; cp5, cp6, calcified portion of pleurites 5, 6 covered by carapace; cx2–cx5, coxae of P2–P5; c6, c7, coxo-pleural condyles of P3, P4; e, epimere (membrane); e6, extension of pleurite 6 covered by carapace; ep5–ep7, exposed pleurites 5–7; e4/5–e6/7, endopleurites 4/5–6/7; g, setting gutter of carapace; ga, gap between laminae of median plate; m, articulating membrane; m.p., median plate; P4–P8, pleurites 4–8; 8, exposed portion of sternite 8; s, sella turcica. Skeletons prepared by S. Secretan.

FIGURE 47. Skeletons of Dorippidae (A, B), Inachidae (C), Hymenosomatidae (D–F), and Inachoididae (G–I). A, B. Medorippe lanata (Linnaeus, 1767), Mediterranean Sea, dorsal view. A, male, after removal of carapace; B, female, after removal of pleurites; C, Inachus dorsettensis (Pennant, 1777), female, Mediterranean Sea (MNHN): sagittal section. D–F, Odiomaris pilosus (A. Milne-Edwards, 1873), New Caledonia (MNHN): D, dorsal view after partial removal of carapace; E, axial skeleton, dorsoventral view after removal of pleurites; F, axial skeleton, sagittal section. G, H, Paulita tuberculata (Lemos de Castro, 1949); G, male 23.0 × 23.0 mm, French Guiana (MNHN-B19511): exposed pleurites 5–8 visible after removal of carapace; H, female: axial skeleton, sagittal section. I, Leurocyclus tuberculosus (H. Milne Edwards & Lucas, 1842), Brazil (MNHN): sagittal section. a, abdomen with pleopods; a1, first abdominal somite; c, carapace; cx5, P5 coxa; e, endopleurite; e.p., exposed pleurite; e5–e8, exposed pleurites 5–8; g, setting gutter of carapace; h, hymenosomian rim; j, junction plate; m, median plate; p, pleurite; pi, pillar; pl, pleopod; s, sella turcica; st, thoracic sternum; t, endosternite; v, location of vulva; y, eye; 3/4–6/7, endosternites 3/4–6/7; 4–8, pleurites 4–8. C, F, H, I: skeletons prepared by S. Secretan.

FIGURE 48. Location of vulvae. A–C, anterior displacement: A, Anasimus latus Rathbun, 1894 (Inachoididae), female 18.4 × 14.0 mm, French Guiana (MNHN-B17807); B, Capartiella longipes (Capart, 1951) (Inachidae), ovig. female 9.4 × 8.1 mm, Nigeria (MNHN-B19602). C, Halicarcinus planatus (Fabricius, 1775) (Hymenosomatidae), female 14.0 × 19 mm, South Pacific, Campbell I. (MNHN-B25960) (schematic); D, Hiroia krempfi Fize & Serène, 1956 (Cryptochiridae), female, Palau: vulvae not widely separated and sternal suture 7/8 complete (schematic, modified from Kropp 1990: fig. 6c); E, Pseudohapalocarcinus ransoni (Fize & Serène, 1956) (Cryptochiridae), female, Guam: vulvae located apart on broad thoracic sternite 6 (schematic, modified from Kropp 1990: fig. 12c). j, sternum/pterygostome junction; m.l., median line; v, vulva; 3–8, thoracic sternites 3–8; 4/5–7/8, interrupted thoracic sternal sutures 4/5–7/8; w, sternal wall.

FIGURE 49. Capartiella longipes (Capart, 1951) (Inachidae), male 8.2 × 6.5 mm, Dahomey (= Benin) (MNHN-B19590). A, carapace, dorsal view: notice exposed pleurites 5–8; B, ventral view; C, thoracic sternum, abdomen lifted, G1 lowered; D, detail of pleotelson with moveable flap supposedly homologous to vestigial uropod. a1, a5, abdominal somites 1, 5; b, pressbutton; c, carapace edge; cx1, P1 coxa; e5–e8, exposed pleurites 5–8; f, flap; G1, first gonopod; pt, pleotelson (somite 6 fused to telson); r, roof formed by thoracic sternite 8; 3–8, thoracic sternites 3–8.

FIGURE 50. A–G. Thoracic sternum (A, C, E, G) and ventral surface of abdomen (B, D, F) of Inachidae (A, B), Inachoididae (C–F), and Majidae (G). A, B, Inachus dorsettensis (Pennant, 1777), male 20.0 × 18.0 mm, France, Saint Martin de Ré (MNHN-B17337); C, D, Collodes leptocheles Rathbun, 1894, male 17.5 × 13.2 mm, Gulf of Mexico (MNHN-B14055); E, F, Pyromaia tuberculata (Lockington, 1877), male 17.0 × 12.2 mm, Baja California (MNHN-B9290); G, Prismatopus harmandi (Bouvier, 1906), male 46.0 × 24.5 mm, holotype, vicinity of Tokyo (MNHN-B22330). H. Palicus caronii (Roux, 1828), male 6.0 × 7.0 mm, eastern Atlantic (MNHN-B16335): ventral surface of abdomen with long socket on somite 6. b, press-button.

FIGURE 56. Diagrammatic representation of patterns of thoracic sternal sutures 4/5–7/8 and modalities of median line (median plate not taken into account) in Eubrachyura. A, pattern 1: sutures 4/5–7/8 complete (uninterrupted), median line along sternites 5–8, may extend on sternite 4; B, pattern 2: only suture 4/5 interrupted, median line along sternites 6–8; C, pattern 3: sutures 4/5, 5/6 interrupted, median line along sternites 7, 8; D, pattern 4: sutures 4/5–6/7 interrupted, median line on sternite 8; E, generalised pattern 5: sutures 4/5–7/8 incomplete, median line variable among subpatterns a-f; F, pattern 6: sutures 4/5–7/8 interrupted, suture 6/7 complete, median line along sternites 7, 8; G, subpattern 5a: sutures 4/5–7/8 interrupted, median line absent; H, subpattern 5b: sutures 4/5–7/8 interrupted, median line along sternites 3–8; I, subpattern 5c: sutures 4/5–7/8 interrupted, median line along sternites 5–8, sometimes partially on sternite 4; J, subpattern 5d: sutures 4/5–7/8 interrupted, median line along sternites 5–7; K, subpattern 5e: sutures 4/5–7/8 interrupted, median line along sternites 7, 8; L, subpattern 5f: sutures 4/5–7/8 interrupted, median line on sternite 4. Each thoracic sternum with same width; all sutures represented parallel, equidistant, and similar. Some additional patterns are not figured.