Munidopsis nereidis, Published, 2007

Published, First, 2007, Species of the genus Munidopsis Whiteaves, 1784 from the Indian and Pacific Oceans and reestablishment of the genus Galacantha A. Milne-Edwards, 1880 (Crustacea, Decapoda, Galatheidae), Zootaxa 1417, pp. 1-135 : 83-85

Munidopsis nereidis n. sp.

( Fig. 39)

Material examined. Gulf of Aden , METEOR 5, Stn 257, 2227– 2250 m: 1 M 8.7 mm (holotype) ( SMF) .

Etymology. The species is dedicated to Nereis, a sea nymph.

Description. Carapace slightly longer than broad; dorsal surface moderately convex from side to side, densely setose, with numerous short striae; regions well delineated by furrows including distinct anterior and posterior cervical grooves. Epigastric region without spines or processes. Posterior cardiac region bluntly triangular, preceded by deep transverse depression. Posterior margin preceded by weakly elevated ridge. Rostrum triangular, moderately compressed, horizontal and slightly upcurved distally, ending in acute tip, length nearly half that of remaining carapace, maximum width 0.3 times carapace breadth; dorsal surface with blunt longitudinal ridge; lateral margins serrate, slightly concave. Frontal margin concave behind ocular peduncle, leading to acute antennal spine, then nearly transverse toward anterolateral corner of carapace. Lateral margins weakly convex and subparallel, carinate, overhanging pterygostomian flap; anterolateral spine welldeveloped, as long as antennal spine, anterior end of anterior cervical groove with distinct notch, anterior branchial margin with one blunt spine and several pronounced striae, posterior cervical groove without notch at anterior end.

Pterygostomian flap smooth, with small short striae and granules, anteriorly unarmed.

Sternum with numerous short setiferous striae. Sternite 3 narrow, nearly 1.7 times wider than long, anterior margin with deep median notch; lateral margin of each lobe convex. Sternite 4 narrowly elongate anteriorly, contiguous to sternite 3; surface weakly depressed in midline; greatest width 4 times that of sternite 3.

Abdomen smooth, unarmed, setose; segments 2ñ4 each with anterior ridge weakly elevated, followed by transverse groove, segments 5–6 smooth; segment 6 with weakly produced posterolateral lobes and nearly transverse posteromedian margin. Telson composed of 8 plates; posterior plates combined about twice as wide as long.

Ocular peduncle immovable, with strong mesial spine, cornea small, subglobular, clearly narrower than peduncle.

Basal article of antennular peduncle with strong dorsolateral and distolateral spines, distomesial angle with granules.

Antennal peduncle not reaching tip of eye spine; article 1 with strong distomesial and distolateral spines, not reaching end of second article; article 2 armed with short distolateral and distomesial spines; articles 3–4 unarmed.

Mxp 3 ischium as long as merus measured on extensor margin, flexor and extensor margins terminating in blunt spine; 15 corneous denticles on crista dentata; flexor margin of merus with 2 blunt spines and several granules, extensor margin with distal spine.

P1 stout, subequal, slightly longer than postorbital carapace, covered with dense soft plumose and simple setae and sparse short striae and granules on merus to dactylus. Ischium with small dorsal, distomesial and distolateral spines. Merus with 3 distal spines (lateral, mesial, and dorsal), and several spines along dorsal side. Carpus as long as high, with one strong mesial spine and one small dorsodistal spine. Palm slightly longer than carpus, and slightly shorter than fingers. Fingers not gaping, distally spooned; prehensile edges each with row of subtriangular teeth, proximal teeth obsolete; fixed and movable fingers ending in several distal teeth; fixed finger with denticulate carina along distolateral margin.

P2–P4 stout, with small granules and short striae on dorsal side, decreasing in size posteriorly; P2 longest; ischium to dactylus with numerous soft plumose and simple setae, more numerous along dorsal and ventral margins. P2 exceeding end of P1; merus nearly 0.5 times carapace length, 1.4 times P4 merus, 2.5 times longer than high, more than 1.5 times length of carpus and less than 1.5 times length of propodus, dorsal margin with row of well-developed spines, increasing in size distally, also present on P3 and P4, ventral margin with acute striae, distally produced; carpus with 1 strong distal spine on dorsal margin, lateral side with longitudinal crest; propodus less than 3 times as long as high, unarmed except for one corneous distal spine on ventral margin; dactylus 0.7 length of propodus; distal claw short, moderately curved; flexor margin nearly straight, with 6 teeth deceasing in size proximally, each with single long seta.

Epipods present on P1.

Remarks. Munidopsis nereidis belongs to the group of species having a wide triangular rostrum, without epigastric spines or processes, main well-developed eye-spine on mesial end of eyestalk, fixed finger of P1 with denticulate carina on distolateral margin, P2 overreaching P1, and epipods on P1. The new species resembles M. profunda from the Celebes Sea and Taiwan ( Baba 2005, Osawa et al. 2006b) and M. solidissima n. sp. from Madagascar. However, they differ in the following aspects:

— The lateral margins of the carapace bear some well-developed spines in M. profunda and M. solidissima , instead of one well-developed anterolateral spine in M. nereidis .

— The carpi and propodi of P2–P 4 in M. profunda and M. solidissima bear a row of spines along dorsal margins, which are absent in the new species.

— The P2–P4 are more slender in M. profunda and M. solidissima than in M. nereidis . The P2 merus is three times longer than high in the former two species, instead of 2.5 times in M. nereidis .

Distribution. Only known from the type locality, Gulf of Aden, at 2227–2250 m.