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 Alainthesius signatus n. sp. ( Figs. 19 G–L; 20C, D; 27D; 34E; 48F; 55E; 83A–C) Megaesthesius sagedae —Crosnier 1975: 110, fig. 1 [Madagascar]; Davie 2013: 475, figs. 3J–N, 4. Not Megaesthesius sagedae Rathbun, 1909 . Type material . Holotype male (2.5 × 3.3 mm ) (MNHN-IU-2013-9472, ex MNHN-B10214), Madagascar , Tulear , 23°23.0’S , 43°36.5’E , dredging, 72 m , C. Jouannic coll., 20.02 . 197372 m . Paratype: female (2.7 × 3.0 mm) (MNHN-IU-2013-9471, ex MNHN-B10213), collected with holotype. FIGURE 35. Chelae of species of Chasmocarcinus . A, C. typicus , Trinidad: holotype male 7.8 × 8.7 mm (USNM 6901); B, C. typicus , Brazil: male 4.0 × 5.1 mm (MCZ CRU-10993, holotype of Chasmocarcinus rathbuni ); C, D, C. typicus , Trinidad: paratype male 7.1 × 9.4 mm (USNM 6901); E, F, C. arcuatus , Brazil: holotype male 5.5 × 6.8 mm (after Coelho & Coelho 1998: figs. 2d, 3e); G, H, C. arcuatus , Brazil: male 3.7 × 5.1 mm (ZRC 2015.220); I, J, C. chacei , Gulf of Mexico: male 6.6 × 8.0 mm (USNM 61489); K, L, C. cylindricus , Jamaica: male 3.6 × 4.9 mm (USNM 42942). FIGURE 36. Chelae of species of Chasmocarcinus . A, B, C. gemmatus n. sp. , Costa Rica: male 7.7 × 11.6 mm (SIO C 1205); C, D, C. hirsutipes , Brazil: holotype male 6.6 × 7.0 mm (after Coelho & Coelho 1998: fig. 6e, f); E, C. latipes , Mexico: holotype female 12.4 × 14.4 mm (USNM 21592); F, C. latipes , Mexico: female 9.2 × 13.0 mm (AMNH 16262, holotype female of Chasmocarcinus ferrugineus Glassell, 1936 ); G, H, C. latipes , Ecuador: male 10.5 × 14.5 mm (AMNH 1941-10668); I, J, C. longipes , Colombia: paratype male 5.5 × 6.4 mm (USNM 78785). FIGURE 37. Chelae of species of Chasmocarcinus , Amboplax n. gen. and Deltopelta n. gen. A, B, Chasmocarcinus meloi , Brazil: holotype male 5.3 × 6.2 mm (after Coelho & Coelho 1998: fig. 9a, b); C, D, Chasmocarcinus mississippiensis , Gulf of Mexico: holotype male 8.3 × 10.4 mm (USNM 64074); E, F, Amboplax peresi , Brazil: male 5.1 × 6.4 mm (ZRC 2015.217); G, Deltopelta obliquus , Bahamas: holotype male 5.2 × 5.1 mm (USNM 20509). Diagnosis . Small size. Carapace ( Figs. 19 G; 20C, D; 27D; Crosnier 1975: fig. 1a, as Megaesthesius sagedae ) subquadrate, 1.1‒1.3 wider than long, dorsal surface smooth; front bilobed, with well-defined median cleft; anterolateral margins straight, with small, sharp teeth arranged in 3 or 4 lobes. Orbits long. Epistome ( Fig. 19 K; Crosnier 1975: fig. 1b, as M. sagedae ) compressed, posterior margin with broad median lobe with median fissure, straight lateral margins without fissures. Eye peduncle ( Figs. 19 I; 27D; Crosnier 1975: fig. 1k, as M. sagedae ) conspicuously long, immobile, cornea long, pigmentation reduced. Antennule ( Figs. 19 G, H; 27D; Crosnier 1975: 1a) greatly enlarged (particularly in males), cannot be folded. Third maxillipeds ( Fig. 34 E; Crosnier 1975: 1e) nearly fill buccal cavern when closed; merus subtriangular, outer margin convex; ischium subquadrate, about same length or longer than merus; outer margins of merus, ischium with teeth. Chelipeds ( Fig. 48 F; Crosnier 1975: fig. 1d) nearly identical in both sexes; cutting margins of both chelae with broad, shallow teeth in both sexes; small chela laterally flattened, shear-like; ventral surface of cheliped merus sometimes with obtuse tubercles. Inner margin of cheliped carpus ( Fig. 20 D) with one or more small, sharp tubercles or teeth. Ventral surface of chelipeds merus with low tubercles. Proportionally long ambulatory legs ( Fig. 19 J; Crosnier 1975: fig. 1i ), P5 merus not reaching front when folded; minute teeth on anterior or posterior or both margins of most articles. Fused thoracic sternites 1, 2 ( Fig. 19 K; 55E) broadly triangular, proportionally wide, short; fused sternites 3, 4 relatively broad. Male pleon ( Fig. 19 L; Crosnier 1975: 1b) with lateral margins of somite 6, fused somites 3–5 slightly convex; postero-lateral regions slightly swollen; telson proportionally short. 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 ( Fig. 83 A, B; Crosnier 1975: fig. 1f, g, as M. sagedae ) stout, distal segment straight with spinules. G2 ( Fig. 83 C; Crosnier 1975: fig. 1h, as M. sagedae ) about 1/2 G1, stout, distal segment long, wide, almost as long as basal segment, directed inward. Adult female unknown. FIGURE 38. Chelae of species of Camatopsis . A, B, C. rubida , Australia: male 10.0 × 10.3 mm (NMV J54592 ); C, D, C. rubida , Australia: male 10.0 × 10.3 mm (NMV J54592 ); E, F, C. rubida , Indonesia: male 9.1 × 9.8 mm (NNM-ZMA 241605c); G, H, C. africana n. sp. , Madagascar: holotype male 5.7 × 6.9 mm (MNHN-IU-2010-1574); I, J, C. africana n. sp. , Madagascar: paratype male 8.3 × 9.8 mm (MNHN-IU-2008-10286). FIGURE 39. Chelae of species of Camatopsis . A, B, C. leptomerus n. sp. , Philippines: holotype male 10.5 × 11.3 mm (NMCR); C, D, C. leptomerus n. sp. , Philippines: paratype female 3.4 × 4.0 mm (ZRC 2015.159); E, F, C. thula n. sp. , Taiwan: holotype male 8.9 × 9.3 mm (ZRC 1999.0662); G, H, C. minor n. sp. , Indonesia: holotype male 3.6 × 4.3 mm (NNM-ZMA); I, J, C. valida n. sp. , Fiji: holotype male 3.6 × 4.9 mm (MNHN-IU-2013-9067). FIGURE 40. Chelae of species of Chasmocarcinops and Hephthopelta . A, B, Chasmocarcinops gelasimoides , Andaman Sea : male 8.8 × 9.5 mm (PMBC 16849); C, D, Chasmocarcinops gelasimoides , Singapore: male 9.5 × 10.3 mm (ZRC 2000.1341); E, F, Hephthopelta lugubris , Australia: male 7.9 × 8.3 mm (NMV J61081 ); G, H, Hephthopelta occidentalis n. sp. , Madagascar: holotype male 6.1 × 6.6 mm, with sacculinid (MNHN-IU-2010-1031). Etymology . The species name is derived from signum , Latin for “signal”, alluding to the large antennules of the species. Remarks . The differences with A. bertrandi n. sp. are discussed under that species. Distribution . Known only from Madagascar , 72 m .