Incultus tuberculosus (A. Milne-Edwards, 1861 )

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 : 167

Incultus tuberculosus (A. Milne-Edwards, 1861)

( Fig. 11D )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 45, 1 8 (CB 25.3 mm with epibranchial tubercles, CL 14.5 mm), NSMT-Cr 30928.

Remarks. The specimen at hand was first referred to the genus Xiphonectes A. Milne-Edwards, 1873 , based on the presence of an acute tubercle at the lateral end of the carapace posterior margin, and identified as X. tuberculosus (A. Milne-Edwards, 1861) owing to the characteristic carapace tuberculation. This species was, however, recently transferred to a new genus Incultus by Koch et al. (2022) as the type species of the genus, together with two congeners, I. alcocki ( Nobili, 1905) and I. brockii (De Man, 1887) .

In this specimen ( Fig. 11D ), the lateral tubercles of the carapace posterior margin are stout and directed obliquely outward. This species is characteristic in the carapace ornamentation and armature: the dorsal surface is flattened overall, areolated with a distinct gastric region, a strong ridge running from the epibranchial tubercle toward the gastric region, and several obtuse tubercles arranged symmetrically around the cardiac region. The carapace anterolateral margin is armed with nine teeth including the obtuse external orbital angle and the strong epibranchial tubercle as usual, but the first, second, third and fifth teeth are distinctly smaller than the fourth, sixth and seventh teeth.

This species was well characterized with the detailed descriptions and figures by the original author (A. Milne Edwards, 1861) and Crosnier (1962), Stephenson and Rees (1967), Dai and Yang (1991), Apel and Spiridonov (1998), and Koch et al. (2022).

Distribution. Sandwich Islands; South China Sea off Hong Kong, 111 m depth; the Philippines, 66–81 m depth; Palau Islands, 30 m depth; Indonesia; Sri Lanka, 50 m depth; Persian Gulf; Madagascar, 25–65 m depth. Recently, Ng et al. (2019) recorded this species from southwestern coast of India at the depth of 200 m.

Figures

Fig. 11. A–B: Bathypilumnus sinensis (Gordon), 8 (NSMT-Cr 30933; CB 8.7×CL 7.0mm) from sta. 45. C: Eumedonus niger H. Milne Edwards, Ə (NSMT-Cr 30935; CB 7.5×CL 7.7mm) from sta. 50. D: Incultus tuberculosus (A. Milne-Edwards), 8 (NSMT-Cr 30928; CB 25.3mm with epibranchial tubercles, CL 14.5mm) from sta. 45. E: Retropluma denticulata Rathbun, Ə (NSMT-Cr 30943; CB 7.8×CL 6.6 mm) from sta. 42. F: Lupocyclus philippinensis Semper, Ə infested by a Sacculina (NSMT-Cr 30924; CB 20.5mm including lateral teeth, CL 17.0mm including frontal teeth) from sta. 45.