Paralomis macphersoni, Muñoz, Isabel & García-Isarch, Eva, 2013

Muñoz, Isabel & García-Isarch, Eva, 2013, New occurrences of lithodid crabs (Crustacea: Decapoda: Lithodidae) from the coasts of Africa, with the description of a new species of Paralomis White, 1856, Zootaxa 3670 (1), pp. 45-54 : 48-52

Paralomis macphersoni sp. nov.

( Figs 1–3 )

Material type. Namibia: NAMIBIA 0502, stn 26, 17 °42.7'S, 11°05.2'E, 1430–1460 m, 11.III.2005, ovigerous female, holotype, CL 85 mm, CW 85 mm (IEO-CD-NB05/035).

Etymology. This new species name honors Dr Enrique Macpherson. We want to recognize, not only his stimulus and support to make the species description but his great contribution to the taxonomy of decapod crustaceans in general, and lithodids in particular.

Distribution. Namibia, 1430–1460 m.

Description. Carapace more or less hexagonal, as long as wide ( Fig. 1 a). Dorsal carapace surface covered with small granules of various size. Granules usually with several short setae ( Fig. 1 b). Regions well-defined. Gastric region rather more prominent than others, with a thick spine on apex ( Figs. 1 c, 2a). Pair of thick granules between median spine and gastro-cardiac groove. Prominence of cardiac and branchial regions similar. Cardiac region with 4 thick granules in square pattern. Each branchial region with 1 or 2 median thick granules and two smaller thick granules near intestinal region.

Basal spine of rostrum more or less horizontal, overreaching end of cornea ( Figs. 1 c, 2a, b), with spiniform tubercles on ventral side ( Fig. 2 c); 2 divergent dorsal spines, upwardly directed, extending well past end of cornea ( Figs. 1 c, 2a, b). Outer orbital spine slightly shorter than eyes ( Figs. 1 c, 2a). Anterolateral spine as long as outer orbital spine. Anterior branchial margin with 2 small spines; first primary marginal branchial spine well developed, followed by 1 smaller spine on lateral branchial margin; second primary marginal branchial spine well developed, followed by 1 smaller spine on non-crested posterior branchial margin, 1 thick granule near intestinal margin.

Abdominal plates smooth, with numerous granules of various size ( Fig. 2 d). Ocular peduncles with several thick terminal spines ( Fig. 2 b).

Basal segment of antennal peduncle with strong distolateral and distomesial spines. Scaphocerite with long, central spine, reaching end of last segment of antennal peduncle, 2 or 3 long spines and 1 or 2 smaller spines on lateral margin, and 4 small spines on mesial margin ( Fig. 3 a, b), dorsal side with granules.

Chelipeds bearing thick spines on mesial border of merus, carpus and hand; distal margin of merus and carpus non crested and smooth ( Fig. 3 c). 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.

Walking legs moderately long. First and second walking legs slightly longer than third. Third walking leg about 2 times carapace length; some acute granules on terminal border of coxa; merus shorter than carapace length (0.36CL), 3.8 times longer than high, about 2 times longer than carpus and about 1.3 times longer than propodus, with thick long spines along dorsal and ventral borders, ventral spines smaller than dorsal, few spines on posterior surface ( Fig. 3 d); carpus with thick spines along dorsal margin; propodus 5 times longer than high, 1.2 times longer than dactylus, with thick long spines along dorsal and ventral margins, ventral spines smaller than dorsal; dactylus slightly curved, with several spines on proximal portion of dorsal edge and with corneous spinules along ventral margin. Scattered tuft of setae on posterior surface, dorsal and ventral margins of articles.

Remarks. Paralomis macphersoni sp. nov. belongs to the group of species within the genus 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 congener is P. pectinata Macpherson, 1988 a from Venezuela at 1409–1629 m. However, the two species are distinguished by features such as:

- The posterolateral crest of the branchial margin of the carapace is smooth and well developed in P. pectinata , whereas this margin is non-crested and has two strong spines in P. macphersoni .

- The scaphocerite has a long central spine, 1 long spine and 1 smaller spine on the lateral border, and 3 small spines on the mesial margin in P. pectinata ; whereas it has 1 long central spine, 2 or 3 long spines and 1 or 2 smaller spines on the lateral margin, and 4 small spines on the mesial margin in the new species.

- The dorsal spines along the merus, carpus and propodus of the walking legs clearly have different sizes in P. pectinata , whereas these spines have a more similar size in the new species.

- The distodorsal margin of the cheliped merus and carpus is clearly crested and with some rounded lobes in P. pectinata , whereas this margin is smooth and not crested in P. macphersoni .

Figures

FIGURE 1. Paralomis macphersoni sp. nov. a – c, female holotype CL 85 mm, CW 85 mm (IEO-CD-NB 05 / 035), Namibia 17 ° 42.7 ' S, 11 ° 05.2 ' E, 1430 – 1460 m. (a) Dorsal habitus. (b) Dorsal carapace granules, lateral. (c) Carapace, lateral. Scale bar = 2 cm (a), 1 cm (b).

FIGURE 2. Paralomis macphersoni sp. nov. a – e, female holotype CL 85 mm, CW 85 mm (IEO-CD-NB 05 / 035), Namibia 17 ° 42.7 ' S, 11 ° 05.2 ' E, 1430 – 1460 m. (a) Anterior carapace, dorsal. (b) Rostrum, lateral. (c) Rostral spines, ventral. (d) Abdomen. Scale bar = 1 cm (a, d), 5 mm (b), 1 mm (c).

FIGURE 3. Paralomis macphersoni sp. nov. a – d, female holotype CL 85 mm, CW 85 mm (IEO-CD-NB 05 / 035), Namibia 17 ° 42.7 ' S, 11 ° 05.2 ' E, 1430 – 1460 m. (a) Right scaphocerite, dorsal. (b) Left scaphocerite, lateral. (c) Right cheliped, lateral. (d) Merus of left third walking leg, dorsal. Scale bar = 1 mm (a, b); 1 cm (c, d).