Thalamonyx gracilipes A. Milne-Edwards, 1873

Shaga, I Bevin, Priya, K, Ramar, Selvakumar, Srinidhi, S, Mohan, G Chandra, Ranganathan, Sukanya, Moulvi, S M M & Mani, Bhuvaneswari, 2023, A Small Collection of Subtidal Crabs (Crustacea: Decapoda: Brachyura) from the Palau Islands Collected by Dredging, Bulletin of the National Museum of Nature and Science. Series A, Zoology 49 (1), pp. 7-42 : 21-22

Thalamonyx gracilipes A. Milne-Edwards, 1873

( Fig. 7C–D )

Thalamonyx gracilipes A. Milne Edwards, 1873a , p. 169, pl. 4 fig. 3.─Alcock, 1899, p. 71.─ Rathbun, 1906, p. 873.─ Edmondson, 1954, p. 251, fig. 26.─ Crosnier, 1962, p. 91, fig. 153.

Thalamonyx danae var. gracilipes A. Milne Edwards : Miers, 1886, p. 192.

Thalamita gracilipes (A. Milne Edwards) : Stephenson and Rees, 1967, p. 20, fig. 2d, h.

Material examined. Inside of Gesodokkuru Reef off Arumonogui, Babelthuap I., Palau Is, dredged, ca. 20 m in depth; 1 ♂ (cb 7.6×cl 5.9 mm), NSMT-Cr 30976; July 13, 1980; K. Baba leg.

Remarks. Evans (2018) showed with the molecular analysis that the genus Thalamonyx is valid and generically distinct from the genus Thalamita . The genus Thalamonyx is represented by Goniosoma danae A. Milne-Edwards, 1869 (type species) and Thalamonyx gracilipes A. Milne-Edwards, 1873 (present species), both of which are close to each other in the general formation of the carapace, chelipeds and ambulatory legs. According to Stephenson and Rees (1967), the most conspicuous difference between the two species is the presence of four ridges in an arc on the mesobranchial and cardiac regions in Thalamonyx gracilipes , instead of no ridges on the cardiac region in T. danae .

The frontal region ( Fig. 7C ) is strongly developed forwards as a plate, with the weakly sinuate margin divided into two lobes by a median minute notch, followed laterally with a large and oblique orbit at each side. The external orbital or first anterolateral tooth is much larger than the following four subequal teeth ( Fig. 7C ). The telson of the male pleon strongly tapers and has a sharp tip ( Fig. 7D ). The G1 is represented by Stephenson and Rees (1967), with which the G1 of the present male agrees well in having the curled setae at the distal part.

Distribution. The records of occurrence are not many, only with several localities in the wide area of the Indo-West Pacific, without intervening localities (Hawaii, New Caledonia, Tonga, Cocos Keeling Island, the Andaman Islands, and Madagascar), 12–77 m in depth. New to the Palau Islands.

Figures

Fig. 7. A–B: Thalamita quadrilobata Miers, ♀ (NSMT-Cr 30974; cb 10.8×cl 7.4mm). C–D: Thalamonyx gracilipes A. Milne-Edwards, ♂(NSMT-Cr 30976; cb 7.6×cl 5.9mm). E–F: Thalamita chaptalii (Audouin), ♂ (NSMT-Cr 30970; cb 12.6×cl 8.2mm) (E); ♂ (NSMT-Cr 30971; cb 8.6×cl 6.0mm) (F). G: Xiphonectes longispinosus (Dana) sensu Sakai (1939), ♂ (NSMT-Cr 30978; cb 17.6mm including epibranchial tubercles×cl 7.1 mm). H: Thalamita sexlobata Miers, ovig.♀ (NSMT-Cr 30975; cb 9.0×cl 6.3mm).