Paralomis arae, Macpherson, 2001

Macpherson, Enrique, 2001, New species and new records of lithodid crabs (Crustacea, Decapoda) from the southwestern and central Pacific Ocean, Zoosystema 23 (4), pp. 797-805 : 799-800

Paralomis arae n. sp.

( Figs 1-3 )

TYPE MATERIAL. — Fiji. MUSORSTOM 10, stn CP 1361, 18°00.00’S, 178°53.71’W, 1058-1091 m, 13.VIII.1998, 1 ♂ holotype 74.5 mm × 72.0 mm (MNHN-Pg 5945).

ETYMOLOGY. — The name arae is one of the southern hemisphere constellations (the Altar).

DISTRIBUTION. — Fiji, 1058-1091 m.

DESCRIPTION

Carapace more or less hexagonal, as long as wide. Dorsal carapace surface covered with small granules of various size. Granules usually with several setae. Regions well-defined. Gastric region rather more prominent than other regions, with a thick spine on apex. Pair of thick granules between median spine and gastro-cardiac groove. Prominence of cardiac and branchial regions similar. Cardiac region with four thick granules in square pattern. Each branchial region with one median spiniform granule and two smaller thick granules near intestinal region ( Figs 1 ; 2A, B ).

Basal spine of rostrum more or less horizontal, slightly overreaching end of corneae, with spiniform tubercles on ventral side; two divergent dorsal spines, upwardly directed, extending well past end of corneae. External orbital spine slightly shorter than eyes. Anterolateral spine slightly shorter than external orbital, one small spine before cervical groove. Eight to nine spines on branchial lateral edge, more developed on ante- rior part of branchial border. Posterolateral angle with small crest, with some spinulous granules. Posterior border with some spiniform granules. Abdomen plates smooth, with numerous gra- nules of various size. Ocular peduncles with several thick terminal spines. Basal segment of antennal peduncle with strong distolateral and distomesial spines. Scaphocerite with long, central spine, reaching end of last seg- ment of antennal peduncle, two long spines and two or three smaller spines on lateral border; me- sial margin with three well-developed spines; three or four spines of various size on dorsal side (Fig Chelipeds bearing thick spines on mesial border of merus, carpus and hand. Some large, more or less acute granules on dorsal surface of merus, carpus and hand. Lateral border of hand with spines. Numerous tuft of setae scattered on mesial and lateral borders and dorsal surface of articles ( Fig. 2C ).

Walking legs moderately long. First and second walking legs slightly longer than third. Third walking leg about two times carapace length; some acute granules on terminal border of coxa; merus shorter than carapace length, about two times longer than carpus and about 1.3 time longer than propodus, with thick spines of various size along dorsal and ventral borders, few spines on posterior surface; carpus with spines along dorsal margin; propodus 1.2 time longer than dactylus, with well-developed spines along dorsal and ventral margins; dactylus slightly curved, with several spines on proximal portion of dorsal edge and with corneous spinules along ventral.3 ). margin. Scattered tuft of setae on posterior surface, dorsal and ventral margins of articles ( Fig.2D ).

REMARKS

Paralomis arae n.sp. belongs to the group of species with few scattered spines on the dorsal surface of the carapace, covered with small, rounded granules varying in size and a prominent gastric region with one central spine. The closest congeners are: P. verrilli (Benedict, 1895) from Bering Sea to California, 850 to 3290 m; P. otsuae Wilson, 1990 from Peru and Chile, 1740 and 1860 m and P. formosa Henderson, 1888 , from the southeastern Atlantic, 400-1600 m ( Sakai 1976; Takeda et al. 1984; Wilson 1990; Macpherson 1992). Paralomis arae n.sp. resembles the types of P. verrilli (National Museum of Natural History, Washington, D-5685), but it is distinguished by features such as: – carapace as long as wide in the new species, clearly wider than long in P. verrilli ; – granules on dorsal carapace surface and posterolateral crest in P. verrilli more prominent than in P. arae n.sp.; – dactylus of the walking legs in P. verrilli as long or longer than propodus, clearly shorter in the new species. The new species is also similar to P. otsuae . However, the spines on the walking legs and chelipeds are much more developed in P. arae n. sp. than in P. otsuae . Furthermore, P. arae n. sp. has the rostrum with several spiniform tubercles on the ventral border and the scaphocerite has some spines on the dorsal side, whereas in P. otsuae the rostrum only has one spinule on the ventral border and the scaphocerite is smooth on the dorsal side. Paralomis arae n.sp. is clearly differentiated from P. formosa by the spines on the dorsal surface and lateral borders of the carapace, much more developed in P. formosa than in the new species.

Figures

FIG. 1. — Paralomis arae n. sp., holotype ♂ cl 74.5 mm (MNHN-Pg 5945), dorsal view.

FIG. 2. — Paralomis arae n. sp., holotype ♂ cl 74.5 mm (MNHN-Pg 5945); A, carapace, lateral view; B, anterior part of carapace, dorsal view; C, right cheliped; D, third left ambulatory leg.

FIG. 3. — Paralomis arae n. sp., holotype ♂ cl 74.5 mm (MNHN-Pg 5945), anterior portion of carapace, including rostrum, eyes and antennal scaphocerite, dorsal view. Scale bar: 5 mm.