Thalamitinae Paulson, 1875

Huang, Yu-Hsuan & Shih, Hsi-Te, 2021, Chthonius rhodochelatus Hadzi 1933, Zoological Studies 60 (60), pp. 1-45 : 23

Subfamily Thalamitinae Paulson, 1875 Genus Thalamita Latreille, 1829 Thalamita gatavakensis Nobili, 1906 ( Figs. 4A , 13 )

Thalamita pilumnoides var. gatavakensis Nobili, 1906: 262 (type locality: Gatavaké, Tuamotus Is., French Polynesia).

Thalamita pilumnoides ssp. gatavakensis – Forest and Guinot 1961: 34, figs. 23–25 (lectotype) ( French Polynesia: Gambier Is.: Mangareva).

Thalamita granosimana – Stephenson 1961: 119, figs. 2E, 4A, pls. 3(4), 4J, 5G (Western Australia). (not Thalamita var. D, granosimana Borradalie, 1902 )

Thalamita gatavakensis – Crosnier 1962: 106, figs. 156 bis. a–c, e (syntype), 177 bis. ( Madagascar: Nosy Be); Stephenson and Rees 1967: 75 ( French Polynesia: Tuamotus Is. and Society Is.; Philippines); Stephenson 1972: 149 ( Indonesia: Bali; Philippines); Wee and Ng 1995: 82, fig. 43; Ng et al. 2008: 154 (list); Sasaki 2019: 9236 (list).

Material examined: Taiwan: 1 male (16.5 × 9.3 mm) ( NTOU), Mao-ao, New Taipei City, coll. CH Yang, 16 Aug. 2006.

Comparative material: Thalamita gloriensis : 2 males (15.7–18.1 × 8.6–10.0 mm) (NCHUZOOL 16540), Waiping, Dongjiyu, Penghu, Taiwan, coll. YH Huang et al., 14 May 2020.

Diagnosis: Carapace transversely hexagonal, 1.8 times broader than long, surface pilose. All anterior carapace ridges and mesobranchial ridges paired, except metagastric and cardiac ridges unbroken ( Fig. 13A ). Front with 2 lobes. Supraorbital margins with 2 notches. Anterolateral margins with 5 teeth, first 3 subequal, tooth 4 smallest, tooth 5 largest ( Fig. 13A ). Basal antennal segment granulated. Chelipeds with surface granulated, merus with 3 spines on inner margin, inner margin with distal end granulated; carpus with 1 spine on inner margin, 3 smaller spines on outer margin; palm with 4 spines on dorsal surface, outer surface with 3 granulated ridges, inner and lower surfaces smooth. P5 with merus having spine on inner margin, distal end of inner margin with small spine; propodus with a row of granules, inner margin with 7–8 spines; dactylus with spinules on distal margins. Pleomere 6 of male pleon with lateral margins subparallel and slightly converging anteriorly. G1 with distal part slender, tip spoon-shaped with bristles ( Fig. 13B–E ).

Distribution: French Polynesia; Australia (western); Indonesia (Bali); Philippines; Taiwan (Mao-ao, New Taipei City; Fig. 1 : no. 1); Japan (incl. Ogasawara Is.; Ryukyus); China (Hainan I.); Vietnam; Malaysia; Thailand (western); Kenya; Tanzania; Mayotte I.; Madagascar (Nosy Be) ( Sasaki 2019; this study).

Ecological notes: The habitat is the intertidal zone with a bottom composed of coral sand ( Crosnier 1962).

Remarks: Thalamita gatavakensis Nobili, 1906 is similar to Tha. pilumnoides Borradaile, 1902 and both are widely distributed in the Indo-West Pacific ( Sasaki 2019). The specimen from Taiwan is consistent with Tha. gatavakensis by the following characters: (1) G1 with distal part curved in Tha. pilumnoides ( Crosnier 1962: fig. 256; Stephenson and Rees 1967: fig. 32a; Yang et al. 2012: fig. 118f) (vs. not curved in Tha. gatavakensis ; Fig. 13B–E ; Crosnier 1962: figs. 177 bis. c, d); (2) male pleon with pleomere 6 broader than long in Tha. pilumnoides ( Borradaile 1902: 207; Crosnier 1962: fig. 255; Stephenson and Rees 1967: fig. 32b; Yang et al. 2012: fig. 118e) (vs. nearly as broad as long in Tha. gatavakensis ; Crosnier 1962: fig. 177 bis. b).

Thalamita gatavakensis is also similar to Tha. gloriensis Crosnier, 1962 , with the latter distributed widely in the Indo-West Pacific as well ( Sasaki 2019). The specimen from Taiwan is consistent with Tha. gatavakensis by the following characters: (1) inner supraorbital lobes slightly arched in Tha. gatavakensis ( Fig. 13A ; Crosnier 1962: fig. 156 bis. a–c, e) (vs. inner supraorbital lobe subparallel to front in Tha. gloriensis ; Crosnier 1962: fig. 156 bis. d); (2) male pleon with pleomere 6 straight on posterior margin in Tha. gatavakensis ( Crosnier 1962: fig. 177 bis. b) (vs. posterior margin convex in Tha. gloriensis ; Crosnier 1962: fig. 169); (3) G1 with distal part slender, lateral and mesial sides with bristles in Tha. gatavakensis ( Fig. 13B–E ; Crosnier 1962: fig. 177 bis. c, d) (vs. G1 with distal part stout, mesial side with bristles in Tha. gloriensis ; Crosnier 1962: figs. 159, 160).

Figures

Fig. 4. Species of the family Portunidae. A, Thalamita gatavakensis Nobili, 1906, male (16.5 × 9.3 mm) (NTOU), Mao-ao, New Taipei City; B, Thalamita spinifera Borradaile, 1902, female (12.6 × 9.0 mm) (NCHUZOOL 16531), Erzihliao Fishing Port, Kaohsiung; C, Thalamitoides quadridens A. Milne-Edwards, 1869, male (25.4 × 13.3 mm) (NTOU), Sansiantai, Taitung; D, Thalamitoides tridens A. Milne-Edwards, 1869, female (16.1 × 8.2 mm) (NCHUZOOL 16520), Dongsha I.; E, Thranita cerasma (Wee & Ng, 1995), female (66.4 × 42.6 mm) (NCHUZOOL 16537), Dongsha I.; F, Thranita coeruleipes (Hombron & Jacquinot, 1846), male (59.7 × 40.5 mm) (NCHUZOOL 16507), Wanlitong, Kenting, Pingtung.

Fig. 13. Thalamita gatavakensis Nobili, 1906, male (16.5 × 9.3 mm) (NTOU). A, carapace; B–E, right G1; B, C, dorsal view; D, E, ventral view.

Fig. 1. Taiwan main island and adjacent islets, with the collection localities shown in gray circles (see Table 1).