Munidopsis vesper, Taylor, Joanne, Ahyong, Shane T. & Andreakis, Nikos, 2010

Taylor, Joanne, Ahyong, Shane T. & Andreakis, Nikos, 2010, New records and new species of the munidopsine squat lobsters (Decapoda: Anomura: Galatheidae: Munidopsinae) from Australia, Zootaxa 2642, pp. 1-18 : 6-8

Munidopsis vesper sp. nov.

( Figs 2 , 5 H).

Type material. WAM C45482, male holotype (cl. 7.8 mm, pcl. 5.8 mm), Australia, Western Australia, N of North West Cape, Barrow L1 transect, 20°57.15–57.56´S, 114°00.78–00.56´E, 1000 m, 9 June 2007 (stn SS05/2007/002) (acq. 038), coll. M. Gomon.

Description. Carapace: 1.1 times as long as wide, moderately convex from side to side; widest at posterior third; dorsal outline subquadrate; surface sparsely setose, without spines, covered with blunt tubercles or granules; regions demarcated; gastric region elevated; anterior gastric region steeply descending to level of rostral base; cardiac region prominent, upraised, deeply separated from gastric region by cervical groove. Anterolateral region swollen, anterior convex; anterolateral spine short, conical, directed almost laterally. Outer orbital angle unarmed, margin broadly convex, junction with anterolateral margin emarginate. Lateral margins subparallel for anterior two-thirds, convergent posteriorly; without spines. Posterior margin upraised, tuberculate. Rostrum horizontal; one-third remaining carapace length; margins concave, minutely dentate tapering to blunt apex; dorsal surface with low granulate, median carina; ventral surface with smooth, blunt carina. Pterygostomian region sparsely granulate, anterior margin pointed.

Sternum: Slightly wider than long; widest at sternite 7. Sternite 3 about half width of sternite 4; anterior margin convex, cristate; posterolateral margins blunt, angular. Sternite 4 fully fused to sternite 3. Sternites 4– 7 surfaces smooth apart from shallow ridges demarcating somites.

Abdomen: Integument unarmed. Tergites 2–4 with 2 elevated ridges separated by median transverse groove. Tergites 4–6 unarmed. Telson broader than long; composed of 8 plates; margins setose; surface with scattered setae. Uropodal endopod unarmed; margins setose.

Eyes: Movable, peduncle smooth, unarmed. Cornea subglobular, as wide as stalk.

Antennule: Basal article with swollen corpus; with 4 or 5 short distomesial spines flanking base of flagellum; with 2 long, slender, distal spines (about half length of corpus), and pair of short (about one-quarter length of distal spines) lateral spines.

Antenna: Basal article unarmed, angular. Articles 2 and 3 subequal, similar, with mesial and lateral spines. Article 2 inner spine shorter than outer. Article 3 inner spine longer than outer. Article 4 inner and outer spines subequal.

Maxilliped 3: Surface smooth. Ischium extensor margin with triangular distal spine; distal flexor margin angular; crista dentata with 23 or 24 corneous teeth. Merus extensor margin with triangular distal spine; flexor margin with proximal 2 triangular spines, 1 proximally and 1 at midlength. Carpus, propodus and dactylus unarmed.

Pereopod 1 (cheliped): Elongate, 3 times carapace length; surfaces rugose, granular and sparsely setose. Ischium with dorsal and ventral distal spine. Merus about twice as long as carpus; with row of 5 dorsal spines; with row of 4 graded spines along proximal half and row of 5 spines along mesial margin including distal spine. Carpus almost 2.5 times as long as high. Propodal palm longer than dactylus, length about 2.5 times height. Dactylus and pollex occlusal margins dentate, without gape; apices multidentate.

Pereopods 2–4 (walking legs): Similar, slender, surfaces smooth or sparsely granular; decreasing in length posteriorly. Pereopod 2 overreaching cheliped carpus. Merus extensor margin with 4–6 spines; flexor margins unarmed. Carpus flexor margin with 3 or 4 low granules, otherwise smooth, unarmed. Propodus 8.8–9.5 times as long as high; surfaces smooth; margins unarmed. Dactylus arcuate, margins smooth, tapering to styliform apex; two-thirds propodus length.

Epipods: Pereopods 1–4 without epipod.

Etymology. From the Latin vesper , west, in reference to the type locality in Western Australia.

Colour in life. Carapace, abdomen and pereopods uniformly pale whitish brown.

Remarks. Munidopsis vesper sp. nov. is similar to M. granulata Miyake & Baba, 1967 ( Japan) , M. palmatus Khodkina, 1973 (Eastern Pacific), M. polita (Smith, 1883) (Caribbean Sea) , and M. truculenta Macpherson & Segonzac, 2005 (off Congo), sharing a granular but spineless carapace and smooth, arcuate, unarmed walking leg dactyli. Together with M. granulata the new species is readily distinguished from M. palmatus , M. polita and M. truculenta by the spinose rather than unarmed extensor margins of the walking leg meri. Munidopsis vesper and M. granulatus agree closely in most respects, having similar carapace granulation, laterally inclined anterolateral carapace spines, and similarly slender walking legs. Munidopsis vesper sp. nov. is distinguished from M. granulata by having two instead of one distolateral spines on the basal antennular article; in the less spinose maxilliped 3 in which the carpus is unarmed (versus spinose along the extensor margin); the extensor margins of the merus and ischium each bear only a short triangular distal spine (versus a long, slender distal spine and two spines along margin); the distal antennal article bears an inner and outer spine (unarmed in M. granulata ).

Distribution. Presently known only from northwestern Australia, north of North West Cape; 1000 m.

Figures

FIGURE 2. Munidopsis vesper sp. nov., holotype, male (cl 7.8 mm, pcl 5.8 mm). A, carapace and abdomen, dorsal view. B, carapace, right lateral view. C, right antenna and antennules, ventral view. D, right basal antennular segment, lateral view. E, right maxilliped 3. F, right maxilliped 3 crista dentata. G, right cheliped. H, right cheliped merus and ischium, ventrolateral view. I – K, left pereopods 2 – 4. L, sternal plastron. M, telson. Scale: A, B, G – K, M = 2.0 mm; C – F, L = 1.0 mm.

FIGURE 5. A, Galacantha subspinosa Macpherson, 2007, lateral view, NMV J 56403; B, dorsal view. C, Munidopsis andamanica MacGilchrist, 1905, lateral view, NMV J 55015, D, dorsal view; E, Munidopsis crenatirostris Baba, 1988, dorsal view, NMV J 56397; F, Munidopsis dasypus Alcock, 1894, dorsal view, NMV J 55006; G, Munidopsis kenselyi Ahyong & Poore, 2004, dorsal view, NMV J 57251; H, Munidopsis vesper sp. nov., dorsal view, holotype male WAM C 45482. All photographs copyright CSIRO.