Chasmocarcinidae

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 10-11

Key to subfamilies of Chasmocarcinidae

1. Antennule with peduncle not particularly enlarged although incapable of being folded into fossa (e.g., Fig. 21 A); dorsal anten-

nular flagellum with elongated aesthetascs (e.g., Fig. 21 A). Carapace subtrapezoidal or subtriangular (e.g., Fig. 2 ); buccal cavern quadrate or rectangular (e.g., Figs. 21 B, 27A)........................................................... 2 - Antennule with greatly enlarged, swollen peduncle (e.g., Fig. 27 B); dorsal antennular flagellum with large, wide aesthetascs (e.g., Fig. 19 A‒C, G). Carapace quadrate or rectangular (e.g., Figs. 19 B, 20E); buccal cavern conspicuously arched, sunken (e.g., Figs. 27 C, 103D)..................................................................... Megaesthesiinae

2. Rounded or quadrate antennular peduncle ( Fig. 22 A); basal antennular article swollen so that antennular flagellum cannot fold into fossa ( Fig. 22 A). Vulva typically not conspicuously large, with thin margins (e.g., Figs. 89 B). Indirect development; marine................................................................................ Chasmocarcininae

- Rectangular antennular peduncle ( Fig. 94 E, J); basal antennular article not swollen so that antennular flagellum can partially fold into fossa ( Fig. 94 E, J). Vulva conspicuously large, with thick margins (e.g., Fig. 99 D, F, H). Direct development (see Davie & Guinot 1996: fig. 2). Freshwater, including inland caves.................................... Trogloplacinae

Figures

FIGURE 2. Overall dorsal view of species of Chasmocarcinus. A, C. typicus, Trinidad: holotype male 7.8 × 8.7 mm (USNM 6901); B, C. typicus, Trinidad: paratype male 4.1 × 4.7 mm (USNM 6901); C, C. typicus, Brazil: male 4.0 × 5.1 mm (MCZ CRU- 10993, holotype of C. rathbuni); D, C. typicus, Brazil: female 8.6 × 10.5 mm (ZRC 2015.211); E, C. arcuatus, Brazil: male 5.7 × 7.7 mm (ZRC 2015.221); F, C. arcuatus, Brazil: female 4.4 × 6.2 mm (ZRC 2015.222); G, C. arcuatus, Brazil: male 3.7 × 5.1 mm (ZRC 2015.220); H, C. arcuatus, Brazil: ovigerous female 4.6 × 6.1 mm (ZRC 2015.220).

FIGURE 19. Species of Megaesthesius and Alainthesius n. gen. A, B, Megaesthesius sagedae, Singapore: male 2.5 × 3.0 mm (ZRC 1995.883); C ‒ F, Megaesthesius yokoyai (after Takeda & Miyake 1969 a: figs. 3 a, 4 f, 4 a, 4 e, respectively); G ‒ L, Alainthesius signatus n. sp., Madagascar: holotype male 2.5 × 3.3 mm (MNHN-IU- 2013 - 9472) (after Crosnier 1975: fig. 1 a, 1 k, 1 j, 1 b, 1 c, 1 i, respectively); M ‒ R, Megaesthesius westralia, Australia: holotype male 3.4 × 3.8 mm (after Davie 2013: figs. 1 A, B, 2 A, D, E, 3 E); S, W, Megaesthesius sagedae, Singapore: male 2.5 × 3.0 mm (ZRC 1995.885); T, X, Megaesthesius migmus n. sp., Philippines: holotype male 4.4 × 4.9 mm (NMCR); U, Y, Alainthesius bertrandi n. sp., New Caledonia: holotype male 3.3 × 4.1 mm (MNHN-IU- 2013 - 9073); V, Alainthesius bertrandi n. sp., Papua New Guinea: female 5.6 × 6.9 mm (MNHN-IU- 2013 - 9012). A, overall habitus; B, C, G, M, dorsal view of carapace; E, left P 4; F, I, frontal view of cephalothorax; H, O, frontal and anterolateral margin of carapace; N, ventral view of cephalothorax; J, right P 3; K, buccal cavity and posterior margin of epistome; Q, right P 4; R, right P 5; D, L, P, male pleon; S ‒ V, posterior margin of epistome; W ‒ Y, left thoracic sternites 7 and 8, “ supplementary plate ”, penis tube and penis. Abbreviations: cx 4 = coxa of P 4; cx 5 = coxa of P 5; p = penis; pt = calcified penis tube; sp = “ supplementary plate ”; st 7 = thoracic sternite 7; st 8 = thoracic sternite 8.

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. 5 c).

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. 8 b); 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 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).

FIGURE 89. Vulvae of species of Chasmocarcinus, Amboplax n. gen. and Deltopelta n. gen. A, Chasmocarcinus typicus, Trinidad: paratype female 6.5 × 6.8 mm (USNM 6901); B, Chasmocarcinus arcuatus, Brazil: female 4.4 × 6.2 mm (ZRC 2015.222); C, Chasmocarcinus chacei, Gulf of Mexico: female 7.8 × 9.5 mm (USNM 61489); D, Chasmocarcinus cylindricus, Puerto Rico: female 6.9 × 9.2 mm (USNM 24551); E, Chasmocarcinus 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, Chasmocarcinus longipes, Colombia: paratype female 5.6 × 6.8 mm (USNM 78785); H, Chasmocarcinus mississippiensis, Gulf of Mexico: female 9.6 × 12.4 mm (USNM 150090); I, Amboplax peresi, Brazil: ovigerous female 4.9 × 6.2 mm (ZRC 2015. 217); J, Deltopelta obliquus, Belize: female 10.7 × 13.0 mm (PMNH, holotype of Hephthopelta superba).

FIGURE 94. Frontal view and third maxilliped of species of Australocarcinus and Trogloplax. A, Australocarcinus riparius, Australia: male 8.8 × 10.2 mm (ZRC 2006.167); B, Australocarcinus kanaka, New Caledonia: female 8.5 × 9.8 mm (ZRC 2009.111); C, D, Australocarcinus palauensis, Palau: holotype female (5.8 × 7.1 mm) (USNM 277853); E, Trogloplax joliveti, New Britain: male 15.7 × 18.6 mm (MNHN-B 20136); F, Trogloplax joliveti, New Britain: female 14.1 × 16.8 mm (ZRC 2015.295); G, Australocarcinus riparius, Australia: holotype male (after Davie 1988: fig. 1 C); H, Australocarcinus kanaka, New Caledonia: paratype female 9.5 × 11.1 mm (after Davie & Guinot 1996: fig. 3 C); I, Australocarcinus palauensis, Palau: holotype female (5.8 × 7.1 mm) (USNM 277853) (after Davie & Guinot 1996: fig. 5 B); J, Trogloplax joliveti, New Britain: holotype male 16.0 × 21.0 mm (MNHN-IU- 2014 - 10457) (after Guinot 1986: pl. 2 B).

FIGURE 99. Female pleon and vulvae of species of Australocarcinus and Trogloplax. A, B, Australocarcinus riparius, Australia: female 9.0 × 11.3 mm (ZRC 2006.167); C, D, Australocarcinus kanaka, New Caledonia: female 8.5 × 9.8 mm (ZRC 2009.111); E, F, Australocarcinus palauensis, Palau: holotype female (5.8 × 7.1 mm) (USNM 277853); G, H, Trogloplax joliveti, New Britain: female 14.1 × 16.8 mm (ZRC 2015.295). A, C, E, G, thoracic sternum with pleon; B, D, F, H, female sterno-pleonal cavity with vulvae.