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 Australocarcinus Davie, 1988 Australocarcinus Davie, 1988 : 260 ; 2002: 504 [in list].— Davie & Guinot 1996 : 278 .— Jamieson & Guinot 1996 : 289 , 294 [sperm ultrastructure].—Ng et al. 2008: 76 [in list].— Guinot et al . 2013 : 42 , 113.— De Grave et al. 2009 : 33 [in list]. Type species . Australocarcinus riparius Davie, 1988 (by original designation; gender masculine) Other species included : Australocarcinus kanaka Davie & Guinot, 1996 Australocarcinus palauensis Davie & Guinot, 1996 Diagnosis . Carapace subquadrate or subrectangular, front bilobed, with shallow median cleft; anterolateral margins arcuate, with crest with or without teeth. Epistome compressed, posterior margin with median lobe with fissure, circular lateral margins without fissures. Eye peduncle filling, short, mobile; cornea normal, pigmented. Third maxillipeds leaving gap when closed; merus quadrate, auricular anteroexternal angle, ischium quadrate, slightly longer than merus. Chelipeds subequal in length, slightly dissimilar in both sexes; cutting margins of both chelae with small teeth in both sexes; fingers of minor chela subcircular in cross-section, not laterally flattened, gently tapering to tip, shear-like, cutting margins with few low teeth; ventral surface of cheliped merus bordered by large tubercles; anterior margin of dorsal surface of propodi with large tooth, Proportionally long or short ambulatory legs, P5 dactylus straight. Meri of ambulatory legs unarmed. 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 nearly straight; postero-lateral regions only slightly swollen; telson proportionally short. Sterno-pleonal cavity of male deep, pressbutton for pleonal holding as small, short tubercle posterior to thoracic sternal suture 4/5 near edge of sternopleonal cavity. Male thoracic sternite 8 proportionally short, rectangular; “supplementary plate” conspicuously narrow, short, rectangular. “Supplementary plate” proportionally narrow, long. G1 stout, distal part with tapering tip, covered with short spinules. G2 longer than G1, basal segment curved; distal segment slightly longer than basal segment, apex with lateral pointed tip. Somites of female pleon with slightly convex lateral margins; telson proportionally long. Sterno-pleonal cavity of female moderately deep, with conspicuously large vulvae close or far apart from each other, covering full extent of thoracic sternite 5, round, thin, raised lip on outer margin, soft membrane across, leaving proportionally small opening. FIGURE 63. Gonopods and ambulatory dactylus of species of Chasmocarcinus . A‒C, C. typicus , Trinidad: holotype male 7.8 × 8.7 mm (USNM 6901); D‒F, C. arcuatus , Brazil: male 5.7 × 7.7 mm (ZRC 2015.221); G‒J, C. arcuatus , Brazil: male 3.7 × 5.1 mm (ZRC 2015.220); K‒M, C. chacei , Gulf of Mexico: paratype male 4.5 × 6.7 mm (USNM 228456, after Felder & Rabalais 1986: fig. 3e, g, h). A, D, G, ventral view of left G1; B, E, H, dorsal view of left G1; I, ventral view of tip of left G1; K, ventral view of right G1 (laterally transposed); C, F, J, L, left G2; M, tip of P5. Scales: A‒H, J‒M = 0.5 mm; I = 0.1 mm. FIGURE 64. Gonopods and epistomes of species of Chasmocarcinus . A‒E, C. cylindricus , Jamaica: male 3.6 × 4.9 mm (USNM 42942); F, C. cylindricus , Puerto Rico: female 6.9 × 9.2 mm (USNM 24551); G‒I, C. gemmatus n. sp. , Costa Rica: male 7.7 × 11.6 mm (SIO C 1205). A, dorsal view of right G1; B, ventral view of right G1; C, ventral view of distal part of distal part of right G1; D, right G2; E, F, posterior margin of epistome; G, ventral view of left G1; H, dorsal view of left G1; I, left G2. Scales: A, B, D = 0.25 mm; E‒I = 0.5 mm; C = 0.05 mm. FIGURE 65. Gonopods of species of Chasmocarcinus . A‒D, C. latipes , Ecuador: male 10.5 × 14.3 mm (AMNH 1941-10668); E‒H, C. longipes , Colombia: paratype male 5.5 × 6.4 mm (USNM 78785); I, C. hirsutipes , Brazil: holotype male 6.6 × 7.0 mm (after Coelho & Coelho 1998: fig. 7d); J, C. meloi , Brazil: holotype male 5.3 × 6.2 mm (after Coelho & Coelho 1998: fig. 9e). A, E, ventral view of left G1; B, ventral view of distal part of left G1; C, F, dorsal view of distal part of left G1; G, ventral view of tip of left G1; D, H, left G2; I, J, ventral view of right G1. Scales: A, D = 0.5 mm; E, F, H = 0.25 mm; I‒K = 1.0 mm; B, C, G = 0.1 mm. FIGURE 66. Gonopods and right P5 dactylus of species of Chasmocarcinus and Amboplax n. gen. A‒C, Chasmocarcinus mississippiensis , Gulf of Mexico: male, carapace width 7.9 mm (USNM 228466, after Felder & Rabalais 1986: fig. 6g, h, i); D‒F, Amboplax peresi , Brazil: male 5.1 × 6.4 mm (ZRC 2015.217). A, ventral view of right G1 (laterally transposed); B, right G2; C, tip of right P5; D, ventral view of left G1; E, dorsal view of left G1; F, left G2. Scales = 0.5 mm. Remarks . The G2 of A. riparius and A. kanaka (unknown in A. palauensis ) is clearly longer that the G1 ( Fig. 98 B, D; Davie & Guinot 1996 : fig. 4A). Davie & Guinot (1996: 279) stated that the “G2 as long as first” in the diagnosis of Australocarcinus . Distribution . Indo-West Pacific region: Palau , Australia ( Queensland ), and New Caledonia .