Munidopsis truculenta, 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 : 46-49

Munidopsis truculenta n. sp. ( Fig. 13 )

Material examined. Off Congo, 05º06’S, 11º18’E, 800–900 m, 18.11.1969: ovig. female holotype, 9.2 mm (MNHN­Ga 4623) .

Etymology. From the Latin truculentus, savage, harsh, in reference to the processes on the carapace.

Description. Carapace quadrangular, dorsal surface sparsely granulose, areas distinct. Gastric region anteriorly elevated from level of rostrum, bearing pair of obtuse, large epigastric processes. Cardiac region with slightly elevated ridge preceded by deep depression; granules of different sizes. Branchial regions with numerous granules, as figured. Frontal margin oblique near rostrum, and transverse lateral to antennal peduncle, without antennal spine. Lateral margins with obtuse processes or lobes separated by welldefined furrows, lobes without spines, with small granules of different sizes. Rostrum relatively wide at base, distally spiniform, nearly horizontal, dorsal surface convex and granulate, length one­third that of remaining carapace. Third thoracic sternite short and wide, width about half that of following sternite.

Abdomen spineless, somites 2 and 3 each with 2 transverse ridges, each anterior ridge elevated; somite 6 with posterolateral lobes distinctly bordered from nearly transverse posteromedian margin. Telson divided into 8 plates, midlateral plates in male with coarse setae on lateral margin, length­width ratio 0.7.

Eyes unarmed, small, movable; cornea distal, slightly wider than eyestalk.

Basal article of antennule with two spines (distomesial and distodorsal), mesial distal margin somewhat produced, laciniate. Antennal peduncle unarmed, with strong blunt distolateral process on article 3 only.

Ischium of third maxilliped more than half as long as merus, extensor margin with distal spine, mesial crest with row of 24 or 25 denticles; merus with 5 flexor marginal spines or acute granules, proximal one larger; extensor margin with spine on distal end; carpus unarmed, propodus relatively slender.

Left cheliped (right missing) slender, subcylindrical, 3.2 times as long as postorbital carapace length, clearly longer than first walking legs; unarmed, with numerous small granules; fingers slightly shorter than palm. Merus clearly overreaching end of rostrum, 2.5 times longer than carpus, nearly 1.7 times as long as palm.

Walking legs similar, slender, spineless. Some granules on merus and carpus. Meri subequal on first and second legs, shorter on third than on preceding legs. First walking leg overreaching end of carpus of cheliped but barely reaching midlength of palm; merus slightly overreaching end of rostrum; length 3.3 times that of carpus and 1.5 times that of propodus; dactyli curving, very slender and sharp, with smooth margins, length about twothirds of propodus. Epipods absent from all pereopods.

Eggs: Diameter, 1.2 mm.

Remarks. The spineless and granular carapace, and slender pereopods with smooth dactyli on the flexor margin link M. truculenta to M. polita ( Smith, 1883) from the Caribbean Sea and the eastern coast of United States (145–860 m), M. granulata Miyake & Baba, 1967 from Sagami Bay, Japan (110–200 m), and M. palmatus Khodkina, 1973 from the coasts of Chile, Gulf of Panama and Gulf of California, between 660 and 1245 m ( Khodkina 1973, Hendrickx 2001, Baba 2005).

The new species is easily distinguished from M. polita by the following characters:

– The dorsal carapace surface is clearly smoother in M. polita than in M. truculenta .

– The rostrum has a dorsal, longitudinal carina in M. polita , this carina is absent in the

new species.

– The chelipeds and merus of the walking legs have numerous small granules in M.

truculenta, whereas these granules are practically absent in M. polita .

The new species is distinctive from M. granulata in the following characters:

– The dorsal carapace surface is more granulated in M. granulata than in M. truculenta .

– The spines of the antennular peduncle are more developed in M. granulata than in M.

truculenta. Furthermore, the antennal peduncle has some distal spines on each article

in M. granulata , instead of being unarmed in the new species.

– The ischium and merus of the third maxilliped each bears an extremely strong spine on the distal end of the extensor margin in M. granulata , instead of a small spine as in M. truculenta .

– The merus of the walking legs has a row of spines along the dorsal border in M. granulata , whereas these spines are absent in M. truculenta .

Munidopsis truculenta is distinguished from M. palmatus by the following characters:

– The anterolateral angle of the carapace bears a distinct spine in M. palmatus , whereas this spine is absent in the new species.

– The merus of the chelipeds in M. palmatus bears two rows of spines on the mesial margin, which are absent in M. truculenta .

Distribution. Only known from the type locality, off Congo, at 800– 900 m. Specific

habitat data are not available.

Figures

FIGURE 13. Munidopsis truculenta n. sp. holotype, ovigerous female (9.2 mm), off Congo, MNHN­Ga 4623. A, general view, dorsal. B, right antennule, antenna and ocular peduncle, ventral. C, sternal plastron. D, endopod of right third maxilliped, lateral. E, dactylus of left second pereiopod, lateral. Scale: 1 mm.