Microtopsis Komai, Ng and Yamada, 2012

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 : 32-33

Genus Microtopsis Komai, Ng and Yamada, 2012

Microtopsis teschi Ng and Castro, 2016 ( Figs. 12D–G , 13 ) Microtopsis teschi Ng and Castro, 2016 , pp. 85 (in key), 86, figs. 18B–C, 80C–F, 81G–N.

Material examined. Entrance to Toagel Mid in Arangel Channel, Babelthuap I., Palau Is., dredged, 40–50 m in depth, mud; 1♂ (cb 3.5×cl 2.9 mm), NSMT-Cr 30995, 1 ♀ (4.0× 3.1 mm), NSMT-Cr 30996; June 19, 1980; K. Baba leg.

Remarks. The genus Microtopsis is composed of two species, the type species, M. takedai Komai, Ng and Yamada, 2012 , described on one male and two females from Okinawa Island in the Ryukyu Islands, 12–30m in depth, and another species, M. teschi Ng and Castro, 2016 , from the northwest of the Kei Islands, Indonesia, 90 m in depth. They are remarkably small, with the carapace breadth 3.1–3.6 mm in M. takedai and 1.9– 2.1mm in M. teschi , but well described and figured by the original authors of both species.

According to Ng and Castro (2016), M. teschi is distinguished from M. takedai by the features that the carapace dorsal surface is covered with small granules (rather smooth in M. takedai ), the anterior part of the carapace lateral margin is fringed with spiniform granules (small blunt granules in M. takedai ), the male telson is triangular in shape (rather semicircular in M. takedai ), the male sixth pleonite is proportionally broader than in M. takedai ), and the G1 is proportionally longer, with the median twist more substrantial and the tip more hook-shaped than in M. takedai . The figures of the present specimen ( Figs. 12D–G , 13 ) agree well with the characters of M. teschi given by Ng and Castro (2016).

Distribution. As mentioned above, this species was originally reported from the northwest of the Kei Islands, Indonesia, 90 m in depth. This is the second report of this small species, and new to the Palau Islands.

Figures

Fig. 12. A–C: Typhlocarcinops decrescens Rathbun, ♀ (NSMT-Cr 30993; cb 8.6×cl 5.8mm) in different views. D–G: Microtopsis teschi Ng and Castro, ♂ (NSMT-Cr 30995; cb 3.5×cl 2.9mm) (D–E), and ♀ (NSMT-Cr 30996; 4.0×3.1 mm) (F–G).

Fig. 13. Microtopsis teschi Ng and Castro, ♂ (NSMT-Cr 30995; cb 3.5×cl 2.9 mm). Carapace (A), front-orbital region (B), left third maxilliped (C), left chela (D), right chela (E), right P4 (F), right P5 (G) and left G1 (H). Scales for ADE, BC, FG=1 mm, H=0.5mm.