Thalamita sexlobata Miers, 1886

Arzivian, Arteen, Alrubaie, Ahmad, Yang, Jessica, Lin, Huiyu, Zhang, Eva & Leong, Rupert, 2022, Crabs (Crustacea, Decapoda) from the Seas of East and Southeast Asia Collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 4. South China Sea, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (4), pp. 147-191 : 169-170

Thalamita sexlobata Miers, 1886

( Fig. 9E–F )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 45, 1 ovig.8 (CB 7.0×CL 6.0 mm), NSMT-Cr 30926; 1 ovig.8 (6.3× 4.5 mm), NSMT-Cr30927.

Remarks. The specimens were identified as Thalamita sexlobata characterized by small body size, the pilose carapace surface, the large orbital fossae, and the presence of short transverse ridges and patch of granules behind the epibranchial ridge. The frontal margin is poorly developed, sinuous and seemingly four-lobed, with the outer lobe overlapping half of the inner lobe, as correctly figured by the original author ( Miers, 1886, fig. 2a) and Crosnier (1962, fig. 196). In the present specimens ( Fig. 9E–F ), the anterior margin of the outer lobe is shallowly concave at the subterminal part and shallowly separated from the supraorbital angle. In this case, the frontal margin is indistinctly six-lobed rather than four-lobed, being somewhat different from the figures given by Crosnier (1962), Takeda (1989), and Wee and Ng (1995). This condition of the frontal lobes approaching to the six-lobed appearance was already mentioned by Stephenson and Hudson (1957). The carapace anterolateral margin is armed with five anteriorly-directed teeth including the external orbital tooth which is the largest of all; the second is slightly smaller than the first, but larger than the subequal third and fifth teeth; the fourth is apparently smaller than the others, but distinct in the specimens examined ( Fig. 9E ).

Distribution. Widely distributed in the Indo-West Pacific from the Hawaiian Islands and the northern Ryukyu Islands southwards to Queensland, Australia, and westwards to Madagascar and the Red Sea through the Andaman Islands and the Persian Gulf, 15–80 m in depth ( Takeda 1989; Apel and Spiridonov, 1998).

Figures

Fig. 9. A–B: Lupocycloporus innominatus (Rathbun), Ə (NSMT-Cr 30923; CB 15.1mm including lateral teeth, CL 10.5mm) from sta. 45. C–D: Charybdis (Archias) vadorum Alcock, Ə (NSMT-Cr 30920; CB 10.7×CL 7.6mm) from sta. 50. E–F: Thalamita sexlobata Miers, ovig.8 (NSMT-Cr 30926; CB 7.0×CL 6.0mm) from sta. 45.