Munidopsis anemia, Macpherson & Segonzac, 2005

Macpherson, Enrique & Segonzac, Michel, 2005, Species of the genus Munidopsis (Crustacea, Decapoda, Galatheidae) from the deep Atlantic Ocean, including cold-seep and hydrothermal vent areas, Zootaxa 1095 (1), pp. 1-60 : 11-13

Munidopsis anemia n. sp. ( Fig. 2 )

Material examined. Bay of Biscay, BIOGAS 1, Stn CM01 , 47º44.3’N, 08º51’W, 1010 m, 04.08.1972: holotype male 34.0 mm (MNHN­Ga 4620), paratype female 3.9 mm .

Etymology. From the Greek aneimon, naked, refering to the smooth surface of the carapace.

Description. Carapace surface unarmed, without epigastric spines, covered by small rugosities. Short striae on anterior branchial region, longer striae on posterior branchial region, as illustrated. Rostrum wide, dorsally weakly carinated, distally trifid, nearly horizontal but slightly upturned distally; antennal spine present. Oblique frontal margin leading to well­developed anterolateral spine (first spine) slightly larger than antennal spine, followed by 2 spines on anterior part of anterior branchial region, anterior (second spine) of these strong, posterior (third spine) smaller; another small spine (fourth) bordering anterior and posterior branchial regions. Anterior margin of third thoracic sternite with small granules, slightly wider than anterior margin of fourth sternite; fourth thoracic sternite subtriangular. Abdomen smooth; segments 2–4 each with anterior elevated transverse ridge; segment 6 bearing posterolateral lobes somewhat exceeding nearly straight transverse median margin. Telson composed of 7 plates; length­width ratio 0.8.

Eyes movable, unarmed; smoothly ovate cornea cupped within broad­based ocular peduncle; cornea relatively large, and slightly wider than third article of antennal peduncle.

Basal article of antennule with distolateral and shorter distodorsal spine; lateral margin slightly swollen. Article 1 of antennal peduncle with distal spines, distolateral spine slightly stronger than distomesial spines; article 2 with well­developed distolateral spine overreaching article 3, not exceeding article 2, clearly longer than distomesial spine; article 3 with strong distomesial spine, overreaching antennal peduncle.

Ischium of third maxillipeds with distal spine on flexor border, merus with strong distal spine on extensor margin, two well­developed spines on flexor border, proximal longer than distal; mesial crest with 21–23 denticles.

Chelipeds 2.5 times carapace length; merus nearly reaching end of rostrum, with 4 strong terminal spines (2 dorsal, 1 mesial, 1 lateral), some well­developed spines on mesial and dorsal margins; carpus 1.4 times longer than broad, with several distal spines, one additional spine on mesial margin; palm spineless, 2.3 times longer than broad; fingers not acuminated, 0.7 times palm length, distally spooned, prehensile edges crenulated; fixed finger without distal crest on lateral margin.

First walking leg clearly not exceeding cheliped. Dorsal crest of meri of walking legs with row of well­developed spines, increasing in size distally; carpi with row of welldeveloped spines along dorsal border, granulate crest along lateral side and not continued on to propodi; propodi unarmed, ca. 1.3 times length of dactyli; each dactylus smoothly narrowed distally, ending in curved sharp spine, flexor margin slightly curving, bearing 5 proximally diminishing spines, each with small movable spinule, ultimate spine rather remote from end of dactylus and much closer to penultimate. Meri of walking legs progressively shorter posteriorly.

Epipod on cheliped; walking legs without epipod.

Remarks. Munidopsis anemia closely resembles M. acuminata from the northwest Atlantic (see above) in having a trifid rostrum, a smooth carapace surface and abdomen, and epipods on the chelipeds. Munidopsis anemia is readily distinguished from M. acuminata by the following characters:

– The rostrum is wider (ca. one­third carapace width, measured at base of rostrum in M. anemia compared to one­fourth carapace width in M. acuminata ) and the spines smaller in M. acuminata than in the new species. The rostrum is also longer in the new species (rostrum ca. 0.5 times carapace length) than in M. acuminata (0.3 times carapace length).

– The antennal, anterolateral and anterobranchial spines of carapace margins are stronger in the new species than in M. acuminata .

– The sternum is narrower in M. acuminata than in M. anemia .

– The basal segment of the antennular peduncle is wider in M. acuminata than in M. anemia , with two subequal and long distodorsal and distolateral spines, whereas the distolateral spine is longer than the distodorsal spine in M. anemia .

– The spines on the segments of the antennal peduncle are longer in the new species than in M. acuminata . The third segment is armed with a well­developed distomesial spine in M. anemia , whereas this segment is unarmed in M. acuminata .

– The fingers are more acuminate in M. acuminata than in M. anemia .

– The walking are legs longer and more slender in M. anemia than in M. acuminata . The spines on the flexor border of the dactyli are better developed and less numerous in M. anemia (5) than in M. acuminata (7).

Distribution and habitat. The species is only known from the type locality, in the Bay of Biscay, at 1010 m, collected among an abundant bathyal community composed of corals, echinoderms and fishes.

Figures

FIGURE 2. Munidopsis anemia n. sp. holotype, male (34.0 mm), Gulf of Biscay, BIOGAS, Stn CM01, MNHN­Ga 4620. A, carapace, dorsal. B, same, lateral. C, anterior part of sternal plastron. D, posterior part of sixth abdominal segment and telson. E, left antennule, antenna and ocular peduncle, ventral. F, endopod of right third maxilliped, lateral. G, right cheliped, lateral. H, right second pereiopod, lateral. I, dactylus of right second pereiopod, lateral. Scale: A–B, G–H = 5 mm, C–F, I = 2 mm.