Acanthodromia margarita ( Alcock, 1899 )

Mclay, Colin L. & Ng, Peter K. L., 2005, On a collection of Dromiidae and Dynomenidae from the Philippines, with description of a new species of Hirsutodynomene McLay, 1999 (Crustacea: Decapoda: Brachyura), Zootaxa 1029 (1), pp. 1-30 : 18-19

Acanthodromia margarita ( Alcock, 1899) ( Fig. 5 )

Dynomene margarita Alcock, 1899: 19 , pl. 2: fig. 3.

Acanthodromia margarita .— Alcock 1900: 134.—Sakai 1965: 43.— Sakai 1976: 31, pl. 7: fig. 2.— Nagai 1989: 43.— McLay 1999: 539, fig. 31.

Material. 1 male, 13.9 x 16.6 mm, 200–300 m, Dec 2000, ZRC 2001.358 ; 1 male, 8.4 x 10.0 mm, 200–300 m, 28 Nov 2001, USNM , ex. ZRC 2001.525 ; 1 male, 10.1 x 11.4 mm, MNHN , 1 male, 11.6 x 12.8 mm, ZRC , in tangle nets, 200–300 m, Jun 2002; 2 males, 9.9 x 10.6 mm, 10.5 x 11.5 mm, 3 females, 7.8 x 8.3 mm, 11.2 x 12.2 mm, 12.3 x 13.4 mm, 2 ovigerous females, 14.7 x 16.7 mm, 17.0 x 18.5 mm, 200–300 m, 25–30 Jul 2003, ZRC 2003.0668 ; 1 male, 13.9 x 16.9 mm, 200–300 m, Nov 2003, ZRC ; 1 female, 11.2 x 12.0 mm, 200–300m, Nov 2003 – Apr 2004, NMCR. All locations in Balicasag Island , Panglao, Bohol, Visayas, Philippines; purchased from local shell fishermen, obtained by tangle nets . 1 female, 13.4 by 15.0 mm, Maribojoc Bay , Panglao, Bohol, Philippines, coll. J. Arbasto, Jul – Feb 2005, ZRC .

Remarks. The type specimen, carapace width 4.5 mm, is a male while the largest known female listed by McLay (1999) measured 15.5 mm in carapace width. The present collection contains a male 13.9 mm in carapace width, thus increasing the known size range for males. Prior to the present study, only one male and two female specimens were known, so the seven males and six females reported here more than quadruple the number of known specimens. As such, this species is not as rare as previously believed. The ovigerous females (16.7 x 14.7 mm, 17.0 x 18.5 mm) carried 880 and 1400 new eggs each, with diameters averaging 0.45 mm, and are the first ovigerous specimens known. With this egg size it can be assumed that A. margarita has a free­swimming larval phase. No eggs were attached to the uniramous first pair of pleopods. The present specimens had light pink spines on carapace and the pereopods with golden yellow dactyli.

Distribution. Acanthodromia margarita was known only from the type locality, Andaman Sea, Indian Ocean and Japan. Its occurrence in the Philippines is a significant new record. The approximate depth range for this species is 120–200 m, although the only exact depth known is for the type specimen that came from 135 m.

Figures

FIGURE 5. Acanthodromia margarita (Alcock, 1899). Male, 13.9 x 16.6 mm, ZRC 2001.358, Philippines. A, overall view; B, frontal view; C, ventral view of abdomen.