Dicranodromia foersteri Guinot, 1993

Takeda, Masatsune, Ohtsuchi, Naoya & Komatsu, Hironori, 2021, Crabs (Crustacea, Decapoda) from the Sea off East and Southeast Asia collected by the RV Hakuhō Maru (KH- 72 - 1 Cruise) 1. Sulu Sea and Sibutu Passage, Bulletin of the National Museum of Nature and Science. Series A, Zoology 47 (2), pp. 65-97 : 71-72

Dicranodromia foersteri Guinot, 1993

( Figs. 4–5 )

Material examined. RV Hakuhō Maru KH-72-1 cruise, sta. 20 (Sibutu Passage; 05°40.9′N, 119°46.3′E – 05°43.1′N, 119°47.0′E; 460–514 m deep); otter trawl; 10 June, 1972; 1˂ (ovig.), NSMT-Cr 28966 .

Measurements. CB 33.3 mm; CL in median line, 33.7 mm; length of rostrum, 3.3 mm; length of first ambulatory leg, 62.2 mm; diameter of egg, 2.2 mm.

Remarks. In the ovigerous female at hand, the carapace was cracked into two, with somewhat damaged posterior part ( Fig. 4A ), but there is no problem to depict the species characteristics. The key prepared by Guinot (1995) was used to identify the present specimen, with combination of the characters that 1) the carapace dorsal surface is smooth and not disguised by the setae of variable lengths, 2) the palm is granulated for its whole outer surface, 3) the last leg is rather long and slender. As a result, it was keyed out to D. martini Guinot, 1995 from the Philippines, or D. foersteri Guinot, 1993 from the Chesterfield Islands, New Caledonia and Vanuatu. Some differences between the two species were mentioned by Guinot (1995), viz. the antero-external tooth of the basal antennal segment is strong and long in D. martini (stout and short in D. foersteri ), the infra-orbital tooth is large and bifid in D. martini (pointed and simple in D. foersteri ), the epistome is armed with some sharp granules in D. martini (unarmed in D. foersteri ), the anterior margin of the buccal frame is fringed with spinules in D. martini (only indistinctly dentated in D. foersteri ), and the dactyli of the first two ambulatory legs are relatively long and subequal to the carpi in D. martini (comparatively short and slightly shorter than the carpi in D. foresteri ). These differences are appli- cable to the ovigerous female examined, and the different length and stoutness of the ambulatory legs are the important criteria among the differences. It is recorded at present that the ambulatory dactyli are half as long as the propodi in D. foersteri , rather than two-thirds in D. martini , although Ng and Naruse (2007) found some variations in the length of the ambulatory carpi in C. martini .

Ng and McLay (2005) described a new species, D. danielae from Balicasag Island in the Bohol Sea, 200–300 m deep, on the comparison with D. doederleini Ortmann, 1892 and D. martini Guinot, 1995 . In D. danielae , however, the outer surface of the chela is smooth, the external orbital tooth is armed with spinules, the posterior margin of the epistome is spinulate, and the meri and propodi of the subdorsal legs are proportionately shorter. In D. danielae , the outer margin of the frontal lobe is straight, differing from the weakly concave margin of D. doederleini and D. martini .

Distribution. This species has been previously recorded from Vanuatu, the Chesterfield Islands and New Caledonia, 495–660 m deep (Guinot, 1993, 1995), and the close congener, C. martini , from the Sulu and Bohol Seas, 437–930 m deep (Guinot, 1995; Ng and Naruse, 2007).

Figures

Fig. 4. Dicranodromia foersteri Guinot, 1993, ovigerous female (NSMT-Cr 28966. CB 33.3mm; CL 37.0mm including rostrum) in dorsal (A) and ventral (B) views.

Fig. 5. Dicranodromia foersteri Guinot, 1993, ovigerous female (NSMT-Cr 28966. CB 33.3mm; CL 37.0mm including rostrum). Front-orbital region with both chelipeds in ventral view (A), front-orbital region in dorsal view (B), right chela in inner view (C), right ambulatory legs in ventral view (D).