Munidopsis alcocki, 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 : 198-200

Munidopsis alcocki sp. nov.

Figs 1 , 9

Munidopsis ? rosacea .—Alcock & Anderson, 1899a: 4, 19.

Munidopsis rosacea .—Alcock & Anderson, 1899b: pl. 40: fig. 4 [Not M. rosacea (A. Milne-Edwards, 1881) = M. serricornis ( Lovén, 1852) ].

Munidopsis (Galathodes) ? tridentata .— Alcock, 1901: 264–265. [Not M. tridentata Esmark, 1857 ].

Munidopsis serricornis .— Ahyong & Poore, 2004: 57 [Bay of Bengal specimens only]; Macpherson, 2007: 97.

Type material. HOLOTYPE: AM P2701 (ex Indian Museum 783/10), male (cl 13.6 mm, pcl 10.1 mm), Bay of Bengal, off Ceylon [ Sri Lanka], 8°44'40"N 81°20'15"E, 296–320 fathoms [542–586 m], green mud, RIMSS Investigator Stn 201, 16 April 1895 . PARATYPES: AM P87579 (ex Indian Museum 783/10), 1 female (cl 12.2 mm, pcl 9.0 mm), collected with holotype ; ZMUC CRU 10114, 1 male (cl 13.9 mm, pcl 10.3 mm), 1 ovigerous female (cl 14.2 mm, pcl 11.1 mm), Laccadive Sea , southwest of Wadge Bank, off the Travancore coast, 7°17'30"N 76°54'30"E, 430 fathoms [787 m], bottom temp 3.3°C , RIMSS Investigator Stn 232, 19 October 1897 .

Other material examined.— Madagascar: MNHN IU- 2011-5082 (Ga1426), 1 male (cl 12.2 mm, pcl 8.8 mm), 1 ovigerous female (cl 9.6 mm, pcl 7.0 mm), 22°18.9'S 43°01.1'E, 735–760 m, Chalutage 108, coll. A. Crosnier, 30 November 1973 .

Diagnosis. Rostrum broad, flat, medially carinate, trifid distally. Carapace unarmed dorsally; surface of dorsal half smooth or with faint short striae; lateral margins with 4 spines (1 anterolateral, 3 branchial); posterior orbital margin transverse; outer orbital spine distinct. Abdominal tergites unarmed. Telson with 8 plates. Maxilliped 3 merus flexor margin with 2 or 3 spines. Cheliped carpus length less than twice width, dorsal surface unarmed; merus with 2 longitudinal rows of prominent spines (mesial, ventromesial). Walking leg meri unarmed or minutely 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; sparsely covered with short, fine setae; surface of anterior half smooth, with few scattered, fine short striae; surface of posterior half with fine distinct striae. Cervical groove indistinct. Epigastric spines absent. Posterior orbital margins transverse to slightly oblique, outer orbital spine prominent. Frontal margins oblique; anterolateral spine similar to outer orbital spine. Lateral margins broadly convex; with 2 spines on anterior branchial margin and spine at junction of anterior and posterior branchial margins. Rostrum broad, 0.3–0.4 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 0.3 width of sternite 4. Posterior margin of sternite 3 contiguous with anterior margin of sternite 4. Sternites smooth, sparsely setose, unarmed.

Abdomen: Tergites with short, fine, scattered setae, unarmed. 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); lateral margin of midlateral plate lined with coarse, relatively stiff setae in males, distally setose in females. Uropodal endopod lateral margins setose, unarmed.

Eye: Ocular peduncle unarmed, sparsely setose; 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 distolateral spines, dorsal spine shorter; distomesial margin with short triangular tooth.

Antenna: Basal article with triangular mesial and lateral tooth, neither overreaching article 2. Article 2 with strong distolateral spine, reaching beyond midlength but not apex of article 3. Article 3 with short distomesial spine. Article 4 with lateral triangular projection. Flagellum as long as cl.

Maxilliped 3: Dactylus, propodus and carpus unarmed. Merus extensor margin with small distal spine, dorsal margin smooth, unarmed; flexor margin with 2 large triangular spines proximally and usually 1 minute spine distally (absent on left side of holotype). Ischium longer than wide, with distal flexor and extensor spine. Crista dentata with 25–28 denticles.

Pereopod 1 (cheliped): Cheliped elongate, 2.3–2.9 pcl (males), 2.3–2.5 (females); with sparsely distributed, simple golden setae, most numerous on dorsal and ventral margins; subcylindrical to ovate. Ischium with dorsal spine; small ventrodistal spine (reduced to low tubercle in holotype). Merus with row of 3–5 small dorsal spines on proximal half to two- thirds; mesial margin with 2 large mesial spines, one distally at carpal articulation, one slightly distal to midlength of margin; ventromesial margin with 1–3 (usually 2) strong spines proximally and distal spine. Carpus stout, about 1.4–1.7 times longer than wide; dorsal margin with distal and subdistal spine, latter largest; small laterodistal spine. Propodus unarmed, palm 1.9–2.2 times as long as wide; mesial margin of palm as long as or longer than dactylus. Pollex and dactylus occlusal margins crenulated, apices with interlocking teeth; pollex occlusal margin with low tooth distal to midlength in male holotype, without gape in female paratype; dactylus occlusal margin with low proximal tooth. Epipod absent.

Pereopods 2–4: Slightly compressed; decreasing in length posteriorly; with scattered, setose striae. Merus elongate; length about 4 times width (pereopod 2) to about 3 times width (pereopod 4); extensor margin or with 3–7 small spines (pereopods 2 and 3) or unarmed (pereopod 4); distal extensor margin with large distal spine; flexor margin irregular but not spinose except for angular distal spine. Carpus with distal extensor spine and small acute tubercle near propodal articulation; extensor margin irregular or serrated (but not spinular); with low, irregular, dorsal carina. Propodus extensor margin irregular, 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 unarmed, with scattered setae; flexor margin with 9 or 10 short triangular teeth, each bearing corneous movable spine and more slender movable spine at base of corneous unguis. Epipods absent.

Egg diameter: 1.2–1.5 mm.

Colour in life. Unknown.

Etymology. Named in honour of Alfred William Alcock (1859–1933) for his major contributions to eastern Indian Ocean deep-sea zoology, especially carcinology.

Remarks. Previous records of M. serricornis (also as M. tridentata and M.? rosacea ) from the northern Indian Ocean (Alcock &Anderson, 1899a, b; Alcock, 1901) and Madagascar ( Macpherson, 2007) are referrable to M. alcocki sp. nov. In addition to the RIMSS Investigator specimens examined here from the Bay of Bengal, Alcock (1899, 1901a) recorded material from the following Investigator station: Stn 218, off North Maldive Atoll, 6°55'06"N 72°55'E, 210 fathoms [384 m], bottom temperature 11.1°C, 21 October 1896.

Northern specimens of M. alcocki agree well with those from Madagascar. Sexual dimorphism in cheliped length is evident in all but the two smallest specimens (male pcl 7.0 mm, female pcl 8.8 mm, MNHN IU-2011-5082), which have similar proportional cheliped lengths (2.3 pcl). Above this size, proportional male and female cheliped lengths differ (males 2.8–2.9 pcl; females 2.4–2.5 pcl). The two ovigerous females carried two (MNHN IU-2011-5082) and eight eggs (ZMUC CR10114), respectively.

As with M. serricornis in the Atlantic Ocean, M. alcocki may be associated with deepwater corals, having been collected together with Caryophyllia paradoxus Alcock , Javania cailleti (Duchassaing & Michelotti) (as Desmophyllum vitreum Alcock ), Madrepora oculata Linnaeus (as Lophohelia investigatoris Alcock ), and Solenosmilia variabilis Duncan (as S. jeffreyi Alcock ) (see Alcock & Anderson, 1899a).

Munidopsis alcocki is most similar to M. serricornis from the Western Atlantic and M. modesta Benedict, 1902 from the eastern Pacific in lacking epigastric spines but is readily distinguished by its minutely rather than strongly spinose extensor margins on the meri of the walking legs.

Distribution. Indian Ocean from Madagascar to the Laccadive Sea, Maldives and Bay of Bengal; 384– 787 m.

Figures

Figure 1. Munidopsis alcocki sp. nov., male holotype, cl 13.6 mm, pcl 10.1 mm (AM P2701). (A) dorsal habitus; (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 finger tips, ventral view; (H) right cheliped ischiomerus, lateral view; (I) right ischiomerus, mesial view; (J) sternal plastron; (K) telson. Scale: A, B, G–I = 2.0 mm; C–F, J, K = 1.0 mm.