Munidopsis macphersoni, Ahyong, 2014

Ahyong, Shane T., 2014, Deep-sea Squat Lobsters of the Munidopsis serricornis Complex in the Indo-West Pacific, with Descriptions of Six New Species (Crustacea: Decapoda: Munidopsidae), Records of the Australian Museum (Rec. Aust. Mus.) 66 (3), pp. 197-216 : 202-204

Munidopsis macphersoni sp. nov.

Figs 3 , 9

Type material. HOLOTYPE: MNHN IU-2010-1429 , female (cl 7.8 mm, pcl 5.2 mm), MacDonald Bank , Austral Islands, French Polynesia, 29°00'S 140°14.9'W, 488–700 m, BENTHAUS DW1874, RV Alis, 4 November 2002.

Diagnosis. Rostrum broad, flat, medially carinate, trifid distally. Carapace with pair of epigastric spines, otherwise unarmed dorsally; surface of dorsal half with granules and short rugae; lateral margins with 5 spines (1 anterolateral, 4 branchial); posterior orbital margin transverse; outer orbital spine distinct. Abdominal tergites unarmed. Telson with 8 plates. Maxilliped 3 merus flexor margin with 2 or more spines. Cheliped carpus length less than twice width, dorsal surface unarmed. Walking leg meri spinose along extensor margin; dactylus flexor margin with movable spines and more slender movable spine at base of corneous unguis. Pereopods without epipods.

Description. Carapace: Moderately convex from side to side; surface with few scattered short setae, almost glabrous; surface of anterior half with granules and small rugae or short striae; surface of posterior half with short striae. Cervical groove indistinct. Pair of epigastric spines. Posterior orbital margins transverse, outer orbital spine prominent. Frontal margins oblique, slightly concave; anterolateral spine similar to outer orbital spine. Lateral margins broadly convex; with 3 blunt spines on anterior branchial margin and spine at junction of anterior and posterior branchial margins. Rostrum broad, slightly less than 0.5 pcl; trifid distally; apex slightly deflected dorsally; median carina distinct; lateral proximal margin convex. Posterior margin unarmed. Pterygostomian flap with short diagonal striae; anterior margin blunt, angular.

Sternum: Sternite 3 about one-third width of sternite 4. Posterior margin of sternite 3 contiguous with anterior margin of sternite 4. Sternites smooth, sparsely setose, unarmed.

Abdomen: Tergites unarmed; surface with few scattered short setae, almost glabrous. Tergites 2–4 with elevated anterior ridge; tergites 2 and 3 also with shallow groove behind anterior ridge. Tergites 4 and 5 with shallow, medially interrupted, transverse groove. Tergite 6 smooth; posterior margin not strongly produced. Telson composed of 8 plates (minute central plate present). Uropodal endopod lateral margins setose, unarmed.

Eye: Ocular peduncle unarmed, glabrous; movable; partially concealed by rostrum. Cornea subglobular, slightly wider than peduncle. Small, slender spine adjacent to lateral margin of eye.

Antennule: Basal article squat, with 2 subequal distolateral spines; distomesial margin with short rounded tooth.

Antenna: Basal article with triangular mesial and lateral tooth, neither overreaching article 2. Article 2 with strong distolateral spine, reaching midlength of article 3. Articles 3 and 4 unarmed. Flagellum slightly longer than pcl.

Maxilliped 3: Dactylus, propodus and carpus unarmed. Merus extensor margin with distal spine; flexor margin with 2 large triangular spines proximally and 2 smaller spines distally. Ischium longer than wide, with acute distal flexor and extensor angles. Crista dentata with 17 or 18 denticles.

Pereopod 1 (cheliped): Cheliped elongate, 2.7 pcl, simple golden setae, most numerous on dorsal and ventral margins; subcylindrical to ovate. Ischium with dorsal spine; without ventral spine. Merus with row of 5 or 6 small, graded dorsal spines along proximal half and large distal dorsal spine; mesial margin with 2 large spines, one distally at carpal articulation, one at distal one-third of margin; ventromesial margin with small proximal spine and strong distal spine. Carpus about 1.8 times longer than wide; mesial margin with distal and subdistal spine, latter largest; small dorsodistal and ventrodistal spine. Propodus unarmed, palm about 2.5 times as long as wide; mesial margin of palm longer than dactylus. Pollex and dactylus occlusal margins crenulated, apices with interlocking teeth. Epipod absent.

Pereopod 2–3 (pereopod 4 unknown): Slightly compressed; decreasing in length posteriorly; with scattered, setose striae. Merus elongate; length about 3.4 times width (pereopod 2); extensor margin with short upright spines; distal extensor margin with large distal spine; flexor margin irregular but not spinose except for strong distal spine. Carpus with distal extensor spine and serrated margin; with low, irregular, dorsal carina. Propodus extensor margin straight, unarmed; flexor margin with movable spine at distal one-third and paired movable spines distally adjacent to dactylar articulation. Dactylus about two-thirds propodus length; extensor margin with scattered setae, unarmed; flexor margin with 8 low triangular teeth, each bearing corneous movable spine and more slender movable spine at base of corneous unguis. Epipods absent.

Colour in life. Unknown.

Etymology. Named for Enrique Macpherson, for his major contributions to galatheoid systematics.

Remarks. Munidopsis macphersoni sp. nov., together with the eastern Pacific M. crinita Faxon, 1893 , differ from other serricornis -complex species in having four instead of three branchial or no marginal spines on the carapace behind the anterolateral spine. Munidopsis macphersoni is readily distinguished from M. crinita in having an almost glabrous body and sparsely setose chelipeds. In M. crinita , the carapace and chelipeds are densely setose. Of other serricornis -complex species, M. macphersoni resembles, M. ternaria , M. comarge and M. atlantis sp. nov. in the granular rather than smooth or weakly striate dorsal surface of the anterior half of the carapace. The new species agrees with M. atlantis sp. nov., and differs from M. ternaria and M. comarge in having distinct (albeit blunt) teeth along the branchial margins; these margins are unarmed in the latter two species. From M. atlantis , M. macphersoni differs in having three instead of four marginal branchial spines on the carapace.

Distribution. Presently known only from the Austral Islands, French Polynesia; 488– 700 m.

Figures

Figure 3. Munidopsis macphersoni sp. nov., female holotype, cl 7.8 mm, pcl 5.2 mm, (MNHN IU-2010-1429). (A) cephalothorax and abdomen, dorsal; (B) carapace, right lateral view; (C) right antenna and antennule, ventral view; (D) right basal antennular article, lateral view; (E) right maxilliped 3; (F) right crista dentata; (G) right cheliped dorsal view; (H) right cheliped carpus and ischiomerus, lateral view; (I) right ischiomerus, mesial view; (J) left cheliped fingers, ventral view; (K) right pereopod 2, dorsal view; (L) right pereopod 3, dorsal view; (M) telson; (N) sternal plastron. Scale: A, B, G–L = 1.0 mm; C–F, M, N = 0.5 mm.