Cryptodromia amboinensis De Man, 1888

Manikandan, K, Megalaa, N, Valliappan, Subramanian, Nandini, K, Rani, Lourdu V, Dakshinamurthi, Senthil & Nagappan, Nagappan, 2022, Crabs (Crustacea, Decapoda) from the Seas of East and Southeast Asia Collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 3. Sahul Shelf, Bulletin of the National Museum of Nature and Science. Series A, Zoology 48 (2), pp. 35-83 : 37-39

Cryptodromia amboinensis De Man, 1888

( Fig. 1A–C)

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 29, 1$( CB 3.2×CL 3.0 mm), NSMT-Cr 30696; 1 $ (4.5× 4.2 mm), NSMT-Cr 30697.

Remarks. The general appearance of the present two females ( Fig. 1A–C) seems to be somewhat different from the photograph given by McLay (1993: fig. 18c), but identified as this small rare species, with characteristic ornamentation of the frontoribital margin and arrangement of the anterolateral and subhepatic tubercles of the carapace. They also seem to be different from the schematic figure of C. demani Alcock, 1900 given by Buitendijk (1939), which has been synonymized with C. amboinensis by McLay (1993), but agree only with the illustration of the frontorbital marginal tuberculation.

Salient aspects of the female specimens at hand are briefly explained as follows: the cara- pace of the larger female ( Fig. 1A) is only slightly wider than long and strongly convex in both directions; it is small, with CB less than 5 mm, but fully mature, with the well-developed pleon fringed with long feathered hairs and covering the whole sternal surface; the pleopods are well developed; the smaller female may be subadult, with the rather narrow pleon and incompletely developed pleopods; both specimens are only slightly smaller than those from New Caledonia, the Philippines and the Persian Gulf reported by McLay (1993), the largest of which is a female from the Persian Gulf with CB 7.1 mm. The paucity of previous records of this species (De Man, 1888; Alcock, 1900, 1901, as Dromia (Cryptodromia) de Manii ; Laurie, 1906, as C. manii ; Buitendijk, 1939, as C. de Manii; McLay, 1993) may be due in part to such the small size as the species, making them easily overlooked.

The frontorbital margin ( Fig. 1A–C) of the carapace in the present specimens is thickly festooned with many, small, elongated granules, and similar to the figure of Cryptodromia de Manii given by Buitendijk (1939) which is somewhat schematic probably with low number of granules. In the present specimens the median frontal tooth ( Fig. 1C) is on a lower level as usual, but rounded at the tip and developed further than the lateral teeth. The anterolateral and subhepatic teeth are also made up with clusters of similar granules. Such marginal ornamentation of the frontorbital border is not seen in the other dromiid species.

The arrangement of tubercles on the subhepatic region and near the orbit was considered by McLay (1993: 204) as the most characteristic for C. amboinensis , commenting that lThis is best seen in De Man (1888, fig. 4a) which shows a small tubercle near the orbit, above the level of the anterolateral margin, an unusual suborbital tooth with a small tubercle on its base, and two subhepatic tubercles in a straight line towards the first anterolateral tooth.z The arrangement of these tubercles is partly referred to the photographs of this paper ( Fig. 1A–B).

Both chelipeds are sparsely covered with long plumose setae and armed with a few compound tubercles. The P2 is densely covered with long plumose setae, and much shorter than the other legs with stout merus and carpus. The P4 is long, with whole surface covered with shaggy setae; the dactylus is talon-like, strongly curved inward and weakly upward, opposing a single propodal spine.

Distribution. Sri Lanka, Mergui Archipelago, New Caledonia, Amboina, the Philippines and now from Australia. The records of bathymetric range are from 18 m in Sri Lanka ( Laurie, 1906) to 33 m in New Caledonia ( McLay, 1993), and now to 52 m depth in Australia.