Charybdis (Archias) vadorum Alcock, 1899

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 : 164-167

Charybdis (Archias) vadorum Alcock, 1899

( Fig. 9C–D )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 50, 1Ə (CB 10.7×CL 7.6 mm), NSMT-Cr 30920.

Remarks. Chopra (1935) thoroughly explained the taxonomic status of Charybdis (Goniohellenus) hoplites var. vadorum Alcock, 1899 , and as a result, regarded it as a full species with C. (G.) sinensis Gordon, 1930 as its synonym.

Charybdis vadorum is a small species, reaching at most about 2.5 cm in the carapace breadth including epibranchial teeth. The carapace surface ( Fig. 9C ) is wholly pilose, with granular patches on the regions; most characteristic is the somewhat Y-shaped, thick cardiac region; otherwise, it is noted on close examination that the metagastric transverse ridge and metagastric region are connected by a median longitudinal line of granules. The front ( Fig. 9C–D ) is low and six-lobed; the median lobe is inclined laterally, the submedian lobe is subtruncated along the inner margin, with the lateral angle hardly attaining the level of the median lobe; the inner part of the submedian lobe slightly overlaps the median lobe; the lateral lobe is narrow and separated from the submedian lobe by a deep notch. The orbit is large, with the diameter wider than half the frontal length. As seen in Fig. 9C–D , of the six anterolateral teeth of the carapace, the first (the external orbital tooth) is directed forward and slightly larger than the second and fourth teeth, but slightly smaller than the third and fourth teeth; the last (the epibranchial tooth) is narrow, much longer than the precedings and sharply directed laterally.

This species was represented with excellent figures as C. (G.) vadorum by Chopra (1935), Leene (1938), and Wee and Ng (1995). Although Wee and Ng (1995) considered C. philippinensis Ward, 1941 as a doubtful synonym of this species, Padate et al. (2010) examined and redescribed the type specimen. Charybdis philippinensis is referable to the subgenus Charybdis , with the carapace surface naked and devoid of tomentum.

Distribution. According to Wee and Ng (1995), this species ranges from Taiwan to the Red Sea through the East and Southeast Asian Sea, India and the Persian Gulf, from depths of 10 to 80 m.

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.