Vellumnus pygmaeus ( Takeda, 1977 )

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 : 30-32

Vellumnus pygmaeus ( Takeda, 1977)

( Fig. 9D )

Planopilumnus pygmaeus Takeda, 1977, p. 131 , fig.

5A–C, pl. 6 figs. C–D.

Vellumnus pygmaeus (Takeda) : Takeda and Komatsu, 2018, p.181, fig. 6G.

Material examined. Inside of Gesodokkuru Reef , off Arumonogui, Babelthuap I., Palau Is., dredged, ca. 20 m in depth; 1♂(cb 5.7×cl 4.5 mm), NSMT-Cr 30994; July 13, 1980; K. Baba leg.

Remarks. Ng (2010) referred three Pilumnus species ( P. vermiculatus A. Milne-Edwards, 1873 , P. labyrinthicus Miers, 1884 and P. penicillatus Gordon, 1930 ) and two Planopilumnus species ( P. minabensis Sakai, 1969 and P. pygmaeus Takeda, 1977 ) to his new genus Vellumnus . All the species have typical Pilumnus - type characters, but are distinctive in having the clearly-patterned symmetrical areolets or labyrinth-like pattern of setae on the carapace. Of five known species, V. labyrinthicus , V. penicillatus and V. pygmaeus are generally close to each other in having the labyrinth-like pattern of setae, but their patterns are distinctly different from each other: Miers (1884) and Ng (2010) for V. labyrinthicus ; Gordon (1931) for V. penicillatus ; Takeda (1977) and Takeda and Komatsu (2018) for V. pygmaeus . The specimen at hand agrees well with V. pygmaeus , especially in having the heartshaped protogastric region, although the epigastric regions of both sides are distinctly isolated by a median longitudinal groove from the median incision of the front.

Distribution. Vellumnus pygmaeus is known from the Ogasawara Islands, 41–105.6 m in depth, and now from the Palau Islands, ca. 20 m in depth, as new to Micronesian waters.

Figures

Fig. 9. A: Gaillardiellus rueppellii (Krauss), ♂ (NSMT-Cr 30985; cb 8.8×cl 6.6mm). B: Metaxanthops acutus Serène, ♂ (NSMT-Cr 30987; cb 6.8×cl 5.5mm). C: Lophoplax sextuberculata Takeda and Kurata, ovig.♀ (NSMT-Cr 30992; cb 5.2×cl 4.0mm). D: Vellumnus pygmaeus (Takeda), ♂ (NSMT-Cr 30994; cb 5.7×cl 4.5mm). E: Chlorodiella corallicola Miyake and Takeda, ovig.♀ (NSMT-Cr 30980; cb 4.8×cl 3.2mm). F: Chlorodiella xishaensis Chen and Lan, ♂ (NSMT-Cr 30983; cb 8.0×cl 5.7mm).