Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea) Author Ng, Peter K. L. Author Castro, Peter text Zootaxa 2016 4209 1 1 182 journal article 37321 10.11646/zootaxa.4209.1.1 2de5b7bf-3975-458a-b200-07ec69f4e013 1175-5326 272646 849BAB5C-464A-4B4A-A586-5742411EDC01 Genus Alainthesius n. gen. Megaesthesius —Crosnier 1975: 110 (part). Type species . Alainthesius signatus n. sp. (gender masculine) Other species included : FIGURE 21. Frontal view of cephalothorax of species of Chasmocarcinus . A, C. typicus , Trinidad: holotype male 7.8 × 8.7 mm (USNM 6901); B C. arcuatus , Brazil: male 5.7 × 7.7 mm (ZRC 2015.221); C, D, C. arcuatus , Brazil: male 3.7 × 5.1 mm (ZRC 2015.220); E, C. chacei , Gulf of Mexico: male 6.6 × 8.0 mm (USNM 61489); F, C. cylindricus , Puerto Rico: neotype female 4.6 × 6.1 mm (USNM 23765); G, C. gemmatus n. sp. , Costa Rica: male 7.7 × 11.6 mm (SIO C 1205); H, C. hirsutipes , Brazil: holotype female 6.6 × 7.0 mm (after Coelho & Coelho 1998: fig. 5c). FIGURE 22. Frontal view of cephalothorax of species of Chasmocarcinus , Amboplax n. gen. and Deltopelta n. gen. A, Chasmocarcinus latipes , Mexico: holotype female 12.4 × 14.4 mm (USNM 21592); B, Chasmocarcinus latipes , Mexico: female 9.2 × 13.0 mm (AMNH 16262, holotype female of Chasmocarcinus ferrugineus Glassell, 1936 ); C, Chasmocarcinus longipes , Colombia: paratype male 5.5 × 6.4 mm (USNM 78785); D, Chasmocarcinus meloi , Brazil: holotype female 5.3 × 6.2 mm (after Coelho & Coelho 1998: fig. 8b); E, Chasmocarcinus mississippiensis , Gulf of Mexico: holotype male 8.3 × 10.4 mm (USNM 64074); F, G, Amboplax peresi , Brazil: male 5.1 × 6.4 mm (ZRC 2015. 217); H, Deltopelta obliquus , Bahamas: holotype male 5.2 × 5.1 mm (USNM 20509). FIGURE 23. Frontal view of cephalothorax of species of Camatopsis and Chasmocarcinops . A, Camatopsis rubida , Andaman Sea : male 4.2 × 4.5 mm (ZMUC CRU 20539); B, Camatopsis rubida , Australia: male 8.3 × 8.5 mm (NMV J54591 ); C, Camatopsis africana n. sp. , Madagascar: holotype male 5.7 × 6.9 mm (MNHN-IU-2010-1574); D, Camatopsis leptomerus n. sp. , Philippines: holotype male 10.5 × 11.3 mm (NMCR); E, Camatopsis leptomerus n. sp. , Philippines: paratype female 3.4 × 4.0 mm (ZRC 2015.159); F, Camatopsis minor n. sp. , Indonesia: holotype male 3.6 × 4.3 mm (NNM-ZMA); G, Camatopsis thula n. sp. , Taiwan: holotype male 8.9 × 9.3 mm (ZRC 1999.0662); H, Camatopsis valida n. sp. , Fiji: holotype male 3.6 × 4.9 mm (MNHN-IU-2013-9067); I, Chasmocarcinops gelasimoides , Andaman Sea : male 8.8 × 9.5 mm (PMBC 16849); J, Chasmocarcinops gelasimoides , Singapore: male 9.5 × 10.3 mm (ZRC 2000.1341). FIGURE 24. Frontal view of species of Hephthopelta and Angustopelta n. gen. A, Hephthopelta lugubris , Australia: male 7.9 × 8.3 mm (NMV J61081 ); B, Hephthopelta occidentalis n. sp. , Madagascar: holotype male 6.1 × 6.6 mm with sacculinid (MNHN-IU-2010-1031); C, Angustopelta aurita , Philippines: holotype female 18.9 × 19.1 mm (USNM 46405); D, Angustopelta aurita , Philippines: male 9.2 × 10.6 mm (ZRC 2015.251); E, Angustopelta cribrorum , Japan: holotype male 13.6 × 14.9 mm (USNM 46388); F, Angustopelta robusta n. sp. , Vanuatu: holotype male 9.3 × 10.7 mm (MNHN-IU-2010-5616); G, Angustopelta modesta n. sp. , Solomon Islands: holotype male 13.3 × 15.1 mm (MNHU-IU-2013-9038); H, Angustopelta aff. modesta n. sp. , Papua New Guinea: female 9.0 × 10.2 mm (ZRC 2015.259). FIGURE 25. Frontal view of species of Chinommatia n. gen. and Notopelta n. gen. A, Chinommatia cavimanus , Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); B, Chinommatia bicuspida n. sp. , Papua New Guinea: paratype female 16.7 × 20.4 mm (MNHN-IU-2011-3461); C, Chinommatia bruuni , Java Sea: male 3.4 × 4.0 mm (ZMUC CRU-1524); D, Chinommatia bruuni , Malaysia: female 5.5 × 7.2 mm (ZRC 2013.0020), Malaysia; E, Chinommatia littoralis , Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); F, Chinommatia turpis n. sp. , Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU-2013-9044); G, Notopelta mortenseni , Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU-7397). FIGURE 26. Frontal view of species of Statommatia n. gen. and Tenagopelta n. gen. A, Statommatia apta , Philippines: holotype 7.8 × 9.4 mm (USNM 46389); B, Statommatia apta , Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); C, Statommatia malagasy n. sp. , Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU-2010-4370a); D, Statommatia knudseni , New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU-6974); E, Statommatia granulosa n. sp. , New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU-2013-9454); F, Tenagopelta pacifica n. sp. , Philippines: holotype male 10.3 × 11.9 mm (NMCR); G, Tenagopelta brachyphallus n. sp. , Australia: holotype male 6.1 × 6.9 mm (NMV J61680 ); H, Tenagopelta potens , Papua New Guinea: male 11.8 × 13.8 mm (MNHN-IU-2011-1504). FIGURE 27. Frontal view of species of Megaesthesius and Microtopsis . A, Microtopsis takedai , Japan: paratype female 3.6 × 2.7 mm (ZRC 2012.0146); B, Megaesthesius sagedae , Singapore: male 2.5 × 3.0 mm (ZRC 1995.883); C, Megaesthesius migmus n. sp. , Philippines: holotype male 4.4 × 4.9 mm (NMCR); D, Alainthesius signatus n. sp. , Madagascar: paratype female 2.7 × 3.0 mm (MNHN-IU-2013-9471); E, Alainthesius bertrandi n. sp. , New Caledonia: holotype male 3.3 × 4.1 mm (MNHN-IU-2013-9073); F, Alainthesius bertrandi n. sp. , Papua New Guinea: female 5.6 × 6.9 mm (MNHN-IU-2013-9012). Alainthesius bertrandi n. sp. Diagnosis . Small size, carapace quadrate, high, front bilobed, with median cleft; anterolateral margins straight, parallel to each other, armed with small teeth arranged in 3 or 4 lobes; dorsal surface smooth. Epistome ( Fig. 19 U, V) compressed, posterior margin with broad median lobe with fissure, straight lateral margins. Eye peduncle conspicuously long, immobile, cornea long, pigmentation reduced. Antennule greatly enlarged (particularly in males), cannot be folded. Third maxillipeds nearly fill buccal cavern when closed; merus subtriangular, outer margin convex; ischium subquadrate, about same length or longer than merus; outer margin with teeth ( A. signatus n. sp. ; Fig. 34 E) or smooth ( A. bertrandi n. sp. ; Fig. 34 F). Chelipeds subequal, nearly identical in both sexes; cutting margins of both chelae with broad, shallow teeth in both sexes; fingers of minor chela relatively broad, proportionally short, prominently flattened laterally, cutting margins blade-like. Inner margin of cheliped carpus with small tooth. Ventral margin of cheliped propodus with teeth. Ventral surface of chelipeds merus smooth or with low tubercles. Ambulatory legs with minute teeth or tubercles on anterior or posterior or both margins of most articles. Fused thoracic sternites 1, 2 broadly triangular, short; fused sternites 3, 4 relatively broad. Male pleon with lateral margins of somite 6, fused somites 3–5 slightly convex; postero-lateral regions slightly swollen; telson proportionally short ( A. signatus n. sp. ; Fig. 19 L) or long ( A. bertrandi n. sp. ; Fig. 55 F). Sterno-pleonal cavity of male deep, press-button for pleonal holding as tubercle at middle portion of thoracic somite 5 near edge of sternopleonal cavity. Male thoracic sternite 8 proportionally long, rectangular; “supplementary plate” conspicuously narrow, only reaching median portion of exposed thorax, short, slightly longer at rounded outer margin. Outer (ventral) surface of penis calcified, resembling plate between “supplementary plate”, sternite 8. G1 stout ( A. signatus n. sp. ) or slender ( A. bertrandi n. sp. ), distal segment straight with spinules. G2 about 1/2 G1, stout, distal segment long, wide, almost as long as basal segment, directed inward. Somites of female pleon with slightly convex lateral margins; telson proportionally long. Sterno-pleonal cavity of female deep, vulvae on outer margins of cavity between sutures 5/6, 6/7. FIGURE 28. Third maxilliped of species of Chasmocarcinus and Amboplax n. gen. A, Chasmocarcinus typicus , Trinidad: holotype male 7.8 × 8.7 mm (USNM 6901); B, Chasmocarcinus typicus , Brazil: male 4.0 × 5.1 mm (MCZ CRU-10993, holotype of Chasmocarcinus rathbuni ); C, Chasmocarcinus typicus , Brazil: male 9.4 × 12.1 mm (ZRC 2015.211); D, Chasmocarcinus arcuatus , Brazil: male 5.7 × 7.7 mm (ZRC 2015.221); E, Chasmocarcinus arcuatus , Brazil: male 3.7 × 5.1 mm (ZRC 2015.220); F, Chasmocarcinus chacei , Gulf of Mexico: female 7.8 × 9.5 mm (USNM 61489); G, Chasmocarcinus cylindricus , Puerto Rico: female 6.9 × 9.2 mm (USNM 24551); H, Amboplax peresi , Brazil: male 5.1 × 6.4 mm (ZRC 2015.217). FIGURE 29. Third maxilliped of species of Chasmocarcinus and Deltopelta n. gen. A, Chasmocarcinus gemmatus n. sp. , Costa Rica: male 7.7 × 11.6 mm (SIO C 1205); B, C. hirsutipes , Brazil: holotype male 6.6 × 7.0 mm (after Coelho & Coelho 1998: fig. 6c); C, Chasmocarcinus latipes , Mexico: holotype female 12.4 × 14.4 mm (USNM 21592); D, Chasmocarcinus latipes , Ecuador: male 10.5 × 14.5 mm (AMNH 1941-10668); E, Chasmocarcinus latipes , Mexico: female 9.2 × 13.0 mm (AMNH 16262, holotype female of Chasmocarcinus ferrugineus Glassell, 1936 ); F, Chasmocarcinus longipes , Colombia: paratype male 5.5 × 6.4 mm (USNM 78785); G, C. meloi , Brazil: holotype male 5.3 × 6.2 mm (after Coelho & Coelho 1998: fig. 8c); H, Chasmocarcinus mississippiensis , Gulf of Mexico: male 7.2 × 8.8 mm (USNM 101082); I, Deltopelta obliquus , Bahamas: holotype male 5.2 × 5.1 mm (USNM 20509). FIGURE 30. Third maxilliped of species of Camatopsis and Chasmocarcinops . A, Camatopsis rubida , Australia: male 8.3 × 8.5 mm (NMV J54591 ); B, Camatopsis africana n. sp. , Madagascar: holotype male 5.7 × 6.9 mm (MNHN-IU-2010-1574); C, Camatopsis leptomerus n. sp. , Philippines: holotype male 10.5 × 11.3 mm (NMCR); D, Camatopsis thula n. sp. , Taiwan: holotype male 8.9 × 9.3 mm (ZRC 1999.0662); E, Chasmocarcinops gelasimoides , Andaman Sea : male 8.8 × 9.5 mm (PMBC 16849); F, Chasmocarcinops gelasimoides , Singapore: male 9.5 × 10.3 mm (ZRC 2000.1341). FIGURE 31. Third maxilliped of species of Hephthopelta and Angustopelta n. gen. A, B, Hephthopelta lugubris , Australia: male 7.9 × 8.3 mm (NMV J61081 ); C, Hephthopelta occidentalis n. sp. , Madagascar: holotype male 6.1 × 6.6 mm with sacculinid (MNHN-IU-2010-1031); D, Angustopelta aurita , Philippines: holotype female 18.9 × 19.1 mm (USNM 46405); E, Angustopelta aurita , Philippines: male 9.2 × 10.6 mm (ZRC 2015.250); F, Angustopelta cribrorum , Japan: holotype male 13.6 × 14.9 mm (USNM 46388); G, Angustopelta robusta n. sp. , Vanuatu: holotype male 9.3 × 10.7 mm (MNHN-IU-2010-5616); H, Angustopelta modesta n. sp. , Solomon Islands: holotype male 13.3 × 15.1 mm (MNHU-IU-2013-9038); I, Angustopelta modesta n. sp. , Solomon Islands: paratype male 11.5 × 13.2 mm (MNHU-IU-2013-9039). FIGURE 32. Third maxilliped of species of Chinommatia n. gen. A, C. cavimanus , Philippines: male 10.1 × 12.2 mm (ZRC 2015.228); B, C. bruuni , Indonesia: male 3.4 × 4.0 mm (ZMUC CRU-1524); C, C. littoralis , Indonesia: holotype female 3.5 × 4.9 mm (NNM-ZMA); D, C. bicuspida n. sp. , Papua New Guinea: paratype female 16.7 × 20.4 mm (MNHN-IU-2011-3461); E, C. turpis n. sp. , Vanuatu: holotype male 3.1 × 4.3 mm (MNHU-IU-2013-9044); F, Notopelta mortenseni , Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU-7397). Scale = 0.5 mm. Etymology . The name is derived from Alain Crosnier , who described the morphology of this species (as Megaesthesius sagedae ) at length, in arbitrary combination with the genus name Megaesthesius . Gender of genus masculine. Remarks . The differences between Alainthesius n. gen. and Megaesthesius Rathbun, 1909 , have been discussed under the remarks of the latter genus. Distribution . Indo-West Pacific region: western Indian and western Pacific oceans.