Munidopsis laurentae, 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 : 31-34

Munidopsis laurentae n. sp. ( Fig. 8 )

Material examined. Off South Africa, WALVIS, Stn 13, 32°18.2’S, 13°15.9’E, 3550 m, 12.01.1979: female holotype 24.7 mm (MNHN­Ga 5295), female paratype 20.0 mm

Etymology. The species is dedicated to our late colleague Michèle de Saint Laurent in recognition of her exceptional contributions to the knowledge of Decapoda , including numerous unpublished notes on the species of the genus Munidopsis .

Description. Carapace exclusive of rostrum about 1.5 times longer than broad, anterior and posterior cervical grooves distinct but not deep. Gastric region moderately convex, with both small and moderate­sized spines and tubercles as figured, lacking elevated rugae. Hepatic region with tubercles. Anterior half of branchial region also with small spines. Posterior half of carapace bearing elevated, interrupted transverse ridges. Frontal margin strongly oblique, slightly convex. Antennal spine present. Posterior margin preceded by row of spines. Lateral margins nearly straight and subparallel, bearing 5 strong spines on anterior half, first anterolateral, smaller than others, somewhat divergent anteriorly, located distinctly mesial to level of remaining spines, second and third spines largest, directed more laterad than preceding, 1 or 3 small additional spines between large spines. Rostrum moderately narrow, with middorsal ridge, somewhat upturned, length one­fourth that of remaining carapace.

Pterygostomian flap anteriorly ending in acute tip.

Sternite 3 narrow, forming apposed lobe bearing anteromedian process at either side of slightly deep median groove, depressed below level of, and, separated by deep groove from, anteriorly narrowed sternite 4.

Abdomen spineless; somites 2 and 3 each with 2 moderately elevated transverse ridges; somites 4–6 without transverse ridge; somite 6 with posteromedian lobe transverse, not produced. Telson consisting of 8 plates, length­width ratio 1.01.

Ocular peduncles slightly movable dorsoventrally, bearing distomesial eye­spine strongly produced forward. Cornea small and lateral.

Basal article of antennular peduncle with strong distodorsal and distolateral spines, distomesially with a few tubercles. Article 1 of antennal peduncle bearing sharp, basally flattish distomesial spine and very small distolateral spine. Article 2 with sharp distolateral spine only. Article 3 narrower than article 2, with distomesial spine distinctly larger than distolateral spine.

Ischium of third maxilliped as long as merus, bearing spine on extensor distal margin and small one on flexor distal margin, mesial crest with row of 16–20 denticles. Merus with 4 sharp flexor marginal spines and 2 sharp extensor distal marginal spines. Carpus unarmed. Propodus relatively slender.

Chelipeds covered with small rugae, 2.2 times as long as postorbital carapace length. Basi­ischium unarmed on mesial margin, distodorsally with strong spine, distoventral margin bearing several small spines at juncture with merus. Merus clearly over­reaching rostrum, armed with spines in 3 rows, distomesial spine strongest. Carpus one­third merus length, bearing row of mesial and dorsal spines. Palm with row of mesial, dorsal and lateral spines, as long as fingers, slightly less than twice as long as broad. Fingers unarmed, not gaping, distally spooned, prehensile edge crenulate. Fixed finger without denticulate carina on distolateral margin.

Walking legs rather long, slender, subcylindrical; first walking leg (P2) over­reaching chelipeds and 2.5 times postorbital carapace length. Meri of P2 slightly longer than that of P3 and 1.3 times that of P4, overreaching rostrum, each bearing dorsal crest with row of well developed spines continued on to corresponding crest on carpus, ventral margin with row of spines. Each carpus having dorsolateral crest without spines, continued on to corresponding crest on propodus. Propodus slightly shorther than merus, about 3 times dactylus length, flexor margin with 2 distal movable spinules, extensor margin sometimes with proximal spine. Dactyli slender, gently but distinctly curved, terminating in acute corneous spine preceded by row of 9 or 10 very low, proximally diminishing processes, each process supporting corneous spine, ultimate process slightly more remote from tip of dactylus than from penultimate process; flexor border nearly straight.

Epipods absent from P1–4.

Remarks. The presence of gastric spines on the carapace, the unarmed abdomen, the absence of pereiopodal, the second walking legs overreaching the tip of the chelipeds, the ocular peduncles bearing a well­developed, anteriorly directed distomesial eye­spine, and the absence of a denticulate carina on the distolateral margin of the fixed finger of the cheliped link the species to M. reynoldsi (A. Milne Edwards, 1880) from the Caribbean Sea and Colombian Basin (3700–4277 m), and M. starmer Baba & de Saint Laurent, 1992 , from North Fiji Basin at 2750 m ( Baba & de Saint Laurent 1992, Tavares & Campinho 1998). Munidopsis laurentae is readily distinguished from M. reynoldsi by the following differences:

– The antennal spine is always present in the new species, whereas this spine is absent in

M. reynoldsi .

– The first anterolateral spine of the carapace in M. laurentae is clearly shorter than the second and third lateral spines, whereas this spine is as long as the second spine in M. reynoldsi .

– The gastric and lateral spines of the carapace are more numerous and better developed in M. laurentae than in M. reynoldsi .

– The propodus of the walking legs is about three times the dactylus length in M. laurentae , instead of being about two times in M. reynoldsi .

The new species is also easily distinguishable from M. starmer by the presence of numerous spines on the gastric region and along the posterior border of the carapace. Munidopsis starmer has only two epigastric spines and the posterior border of the carapace is unarmed.

The two specimens were collected together with an abundant fauna composed of octocorals, decapods including one Munidopsis bairdii , echinoderms, tunicates and fishes. Distribution. Only known from the type locality, off South Africa at 3550 m. Specific habitat data are not available .

Figures

FIGURE 8. Munidopsis laurentae n. sp., holotype, female (24.7 mm), off South Africa, WALVIS, Stn 13, MNHN­Ga 5295. A, carapace, dorsal. B, same, lateral. C, 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, D, G–H = 5 mm, C–F, I = 2 mm.