Paralomis dawsoni, 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 : 802-805

Paralomis dawsoni n. sp.

( Fig. 4 )

Paralomis sp. Macpherson 1990: 225, figs 2c, 4.

TYPE MATERIAL. — New Caledonia. Trap , seaward side of the reef, holotype 1 ov. ♀ 71 × 72 mm (MNHN-Pg 4278) ; 3 ♀ ♀ paratypes 62 × 60 to 72 × 72 mm (MNHN- Pg 4275, 4279).

ETYMOLOGY. — This species is dedicated to E.W.Dawson, National Museum of New Zealand, for his important contribution to lithodid taxonomy. DISTRIBUTION. — New Caledonia.

DESCRIPTION

Carapace more or less hexagonal, as long as wide, surface covered with rounded, clustered granules of different sizes. Granules with several short setae. Regions well-defined. Gastric region slightly more prominent than rest. Prominence of cardiac and branchial regions similar ( Fig. 4A ).

Basal spine of rostrum short more or less horizontal, slightly overreaching end of corneae, with several granules on ventral side; pair of somewhat divergent, dorsal spines, pointing slightly upwards, not exceeding end of corneae. External orbital spine shorter than eyes. Anterolateral spine slightly shorter than external orbital. Anterolateral margins of carapace with 11 to 13 stout spines, of different size, extending to level of gastro-cardiac groove. Posterolateral and posterior borders with granules.

Abdomen plates with numerous rounded granules of various size.

Ocular peduncles with several thick terminal and dorsal spines.

Basal segment of antennal peduncle with strong distolateral and distomesial spines. Scaphocerite with a long, central spine, slightly overreaching end of last segment of antennal peduncle, two or three long spines and two to four smaller spines on lateral border; mesial margin with three to five spines; some acute granules on dorsal side ( Macpherson 1990: fig. 4).

Chelipeds with merus armed with spines in terminal border, one spine larger than others; carpus with six to seven well-developed spines not situated on a crest; numerous spines, less develop- ed than spines of carpus, on dorsal border of hand; numerous granules scattered over all articles; numerous tuft of setae scattered on mesial and lateral borders and dorsal surface of articles ( Fig. 4B ).

Walking legs moderately long, with numerous granules on posterior surface of articles. First and second walking legs slightly longer than third. Third walking leg less than 1.5 time carapace length; some acute granules on terminal border of coxa; merus about 1.5 time longer than carpus and about 1.3 time longer than propodus, with spines of various size along dorsal and ventral borders; carpus with spines along dorsal margin; propodus as long as dactylus, with well-developed spines along dorsal margin and some smaller spines along ventral edge; dactylus slender, slightly curved, with several spines on proximal portion of dorsal edge and with corneous spinelets along ventral margin. Scattered tuft of setae on posterior surface, dorsal and ventral margins of articles ( Fig. 4C ).

REMARKS Paralomis dawsoni n.sp. belongs to the group of species with the carapace, abdomen and pereiopods surfaces densely covered with clusters of rounded granules, varying in size, without spiniform tubercles or spines. This group is represented in the Pacific ocean by three species: P. granulosa (Jacquinot, 1847) from the southern coasts of Argentina and Chile, P. dofleini Balss, 1911 from Japan and P. haigae Eldredge, 1976 from Guam, New Caledonia and Samoa Islands ( Sakai 1971, 1976; Macpherson 1988, 1990; Dawson 1989; Ikeda 1998). Paralomis dawsoni n.sp. appears to be most closely related to P. granulosa , but the two can be differentiated by the following characters: – the gastric region is usually more convex in P. dawsoni n.sp. than in P. granulosa ; – the spines on the carapace margins are larger in the new species than in P. granulosa ; – the scaphocerite has more and longer spines in P. dawsoni n.sp. than in P. granulosa ; – the carpus of the chelipeds has a high crest dorsally, with six or seven stout spines in P. granulosa , this crest is not present in P. dawsoni n.sp. although some well-developed spines are present; – the walking legs are longer and more slender in the new species than in P. granulosa . The propodus of the third walking legs is more than 2.5 times longer than higher in P. dawsoni n.sp., being less than two times in P. granulosa . The new species is also close to P. dofleini and P. haigae , although it is readily differentiated by the following features: – the rostrum has not dorsal spines in P. dofleini and P. haigae , whereas two dorsal spines are always present in P. dawsoni n.sp.;

– the carapace margins lack spines, and the walking legs have few and small spines in P. dofleini and P. haigae ; the carapace edges have welldeveloped spines, and the walking legs have numerous dorsal spines in the new species;

– the granules on the carapace have few very short scattered setae in the new species, whereas these setae are more numerous and form a circle in P. haigae .

Figures

FIG. 4. — Paralomis dawsoni n. sp., holotype ov. ♀ cl 71 mm (MNHN-Pg 4278); A, dorsal view; B, right cheliped; C, third left ambulatory leg.