Thalamita gatavakensis Nobili, 1906

Padate, Vinay P., Periasamy, Rengaiyan, Rivonker, Chandrashekher U. & Ingole, Baban S., 2023, Coral reef-associated brachyuran fauna (Crustacea: Decapoda: Brachyura) from Angria Bank off the west coast of India, Zootaxa 5357 (3), pp. 398-422 : 407-408

Thalamita gatavakensis Nobili, 1906

( Fig. 4E–H )

Thalamita pilumnoides var. gatavakensis Nobili, 1906b: 262 , figs. 30a–b, 31a–e (type locality: Gatavaké , French Polynesia).

Thalamita pilumnoides ssp. gatavakensis .— Forest & Guinot 1961: 34, figs. 22a–b, 23–25.

Thalamita gatavakensis .— Crosnier 1962: 106, figs. 177a–d.— Stephenson & Rees 1967: 75.— Stephenson 1972a: 149.— Stephenson 1972b: 20 (key), 47.— Wee & Ng 1995: 82, figs. 43a–d.— Stephenson 1976: 21.

Thalamita granosimana .— Stephenson 1961: 119, figs. 2E, 4A, pl. 3, fig. 4, pls. 4J, 5G. [Not T. granosimana Borradaile, 1903 )]

Material examined. 2 males (5.1 × 3.1 mm, 5.7 × 3.4 mm) ( NIO /BOD/AB/BRY/00011), RVSS 11 , west of Vijaydurg , Arabian Sea, 16.62°N, 72.01°E, 24 m depth, Van Veen grab, coll. R. Periasamy, 8 January 2014 .

Diagnosis. Carapace hexagonal, tomentose ( Fig. 4E ); frontal margin bilobed, internal orbital angles narrower than frontal lobes; carapace ridges including 1 pair each of frontals, protogastrics, mesogastrics, mesobranchials and epibranchials, median metagastric and cardiac ridges; anterolateral margins divided into 5 teeth, fourth tooth rudimentary ( Fig. 4F ). Basal antennal article with 8 tubercles ( Fig. 4G ). Cheliped merus with 3 spines on anterior margin; manus with 6 spines on dorsal surface ( Fig. 4E ). G1 distal tip recurved spoon-shaped, with spine on spoonedtip, inner surface with long backwardly directed spine and inner surface with 3–4 bristles ( Fig. 4H ).

Colouration. Fresh specimen: carapace reddish brown with yellowish speckles ( Fig. 4E ). Preserved specimen: brown with lighter setae ( Fig. 4F ).

Biology. Known to inhabit corals ( Wee & Ng 1995) in intertidal coralline sand ( Crosnier 1962) and lagoons ( Forest & Guinot 1961); 20–24 m ( Wee & Ng 1995; present study). The present specimens were collected from sandy substratum, at 24 m depth, covered with macroalgae.

Remarks. Nobili (1906b) provided a short description of a new variety ( gatavakensis ) of T. pilumnoides from French Polynesia. Forest & Guinot (1961) compared T. pilumnoides gatavakensis with T. pilumnoides and proposed its elevation to species level. Crosnier (1962) provided a short, illustrated description of T. gatavakensis and elevated it to species level based on the differences (with T. pilumnoides ) in morphologies of male pleon and G1. Stephenson’s (1972b) key to the Indo-West Pacific portunids grouped this species along with T. iranica Stephensen, 1946 , T. granosimana Borradaile, 1902 , T. admete (Herbst, 1803) , T. auauensis Rathbun, 1906 and T. gloriensis Crosnier, 1962 owing to G1 with moderately curved tip. This species differs from the above-mentioned congeners in having G1 with curved distal tip bearing very few setae. Wee & Ng (1995) provided a short, illustrated description of T. gatavakensis . The morphology of the present specimens conformed to the descriptions and illustrations provided by Crosnier (1962) and Wee & Ng (1995) in the bilobed frontal margin of carapace, the presence of cardiac ridge and mesobranchial ridges in addition to 1 pair each of frontal, protogastric, mesogastric, metagastric and epibranchial ridges, a straight inner supraorbital lobe narrower than the frontal lobe, and a spoon-shaped, recurved distal tip of G1 bearing very few terminal bristles.

Geographical distribution. Madagascar, Seychelles, Malaysia, Philippines, Indonesia, Western Australia, Saipan, Tuamotu ( Wee & Ng 1995); eastern Arabian Sea off India (present study). The present observation is the first record from Indian waters.

Figures

FIGURE 4. Xiphonectes macrophthalmus (Rathbun, 1906), female (NIO/BOD/AB/BRY/00010, 6.0 × 2.9 mm), eastern Arabian Sea, India: (A) dorsal habitus (fresh colour); (B) carapace, dorsal view; (C) cephalothorax, ventral view; (D) right cheliped, dorsal view. Thalamita gatavakensis Nobili, 1906, male (NIO/BOD/AB/BRY/00011, 5.7 × 3.4 mm), eastern Arabian Sea, India: (E) dorsal habitus (fresh colour); (F) carapace, dorsal view; (G) cephalothorax, ventral view; (H) G1 distal portion, pleonal view. Scale bars: A–G, 1 mm, H, 0.5 mm.