Munidopsis treis, Ahyong & Poore, 2004

Ahyong, Shane T. & Poore, Gary C. B., 2004, Deep-water Galatheidae (Crustacea: Decapoda: Anomura) from southern and eastern Australia, Zootaxa 472 (1), pp. 1-76 : 62-65

Munidopsis treis n. sp. ( Fig. 15 )

Munidopsis serricornis . — Baba & Poore, 2002: 241–244, fig. 6C, 7B, 8B, 9C, D [part, not M. serricornis ( Lovén, 1852) ].

Type material. HOLOTYPE: SAM C6091 , ovigerous female (16.4 mm), 278 km W of Cape Catastrophe, Great Australian Bight , South Australia, 34°58’S, 132°32’E, 800 m, B. Jubb, 20 Aug 1988 . PARATYPES: SAM C6092 , 1 male (10.2 mm), 3 females (12.9–14.9 mm), type locality ; NMV J44745 , 1 female (9.4 mm), 82.1 km SSE of Southeast Cape, Tasmania, ‘ Sister 1’ seamount, 44°16.8’S, 147°15.6’E, 820 m, epibenthic sled , T. Stranks, 23 Jan 1997 ; AM P13167, 1 ovigerous female (20.8 mm), E Tasmanian coast, 366–549 m, FRV Derwent Hunter, Jan 1955 .

Diagnosis. Carapace cervical groove indistinct; without dorsal spines; frontal margins slightly oblique, with slender antennal spine and strong anterolateral spine followed posteriorly by 2 strong spines on hepatic margin. Rostrum broad, trifid distally. Third sternite about one­third width of sternite 4; posterior margin on sternite 3 broadly contiguous with anterior margin of sternite 4. Sternites smooth, unarmed. Abdominal tergites unarmed. Sixth tergite with posterior margin not strongly produced. Telson composed of 7 plates. Eyestalk unarmed, slightly movable, partially concealed by rostrum. Maxilliped 3 merus with slender distal extensor spine; flexor margin with two proximal spines and several small denticles. Pereopods without epipod. Cheliped elongate, shorter than twice carapace length; carpus with strong distal spines and with strong middorsal spine. Walking legs with spinose extensor margin; dactylus flexor marginwith 6 or 7 stout triangular teeth, each bearing slender movable spine.

Description. Carapace: Moderately convex from side to side; sparsely covered with short, fine setae and fine pits; cervical groove indistinct; without dorsal spines. Frontal margins slightly oblique, with slender antennal spine and strong anterolateral spine followed posteriorly by 2 strong spines on hepatic margin; lateral margins subparallel, slightly wider anteriorly. Rostrum broad, about half remaining carapace length; trifid distally; apex spiniform, inclined dorsally; moderately carinate dorsally; lateral proximal margin straight. Anterior margin of pterygostomian flap with anterior spine.

Sternum: Third sternite about one­third width of sternite 4; posterior margin on sternite 3 broadly contiguous with anterior margin of sternite 4. Sternites smooth, unarmed.

Abdomen: Tergites with short, fine, scattered setae, without spines. Second to fourth tergites with elevated anterior ridge; second and third also with shallow groove behind anterior ridge. Sixth tergite with posterior margin not strongly produced. Telson composed of 7 plates. Uropodal endopod with serrate lateral margins.

Eye: Ocular peduncle unarmed, non­setose; slightly movable; partially concealed by rostrum. Cornea subglobular, slightly wider than peduncle; with small spine between eyes and antennal peduncle.

Antennule: Basal segment with two distolateral spines; distomesial margin produced.

Antenna: Basal segment with mesial and lateral tooth. Second segment with strong distolateral spine; distomesial margin angular, apex sometimes bifid. Third segment with distomesial spine. Fourth segment with lateral triangular projection.

Maxilliped 3: Dactylus, propodus and carpus unarmed. Merus with slender distal extensor spine; flexor margin with two proximal spines and several small denticles.

Epipods: Pereopods 1–4 without epipods.

Pereopod 1 (cheliped): Elongate, shorter than twice carapace length; sparsely setose and rugose; subcylindrical to ovate. Propodus with 3–5 small spines on dorsal margin; palm about 3 times as long as high; dorsal margin of palm longer than dactylus. Pollex and dactylus with occlusal margins crenulate; distally slightly ‘hollowed’on internal margin. Carpus with strong distal spines; with strong middorsal spine and smaller spines on lateral surfaces. Merus with strong distal spines and row of strong dorsal spines; with small spines on lateral surface. Ischium with ventrodistal spine and row of dorsal spines.

Pereopod 2–4: Setose; slightly compressed. Merus with spinose extensor margin and distal triangular spine on flexor margin. Carpus with distal flexor spine and row of extensor spines; with 2 low, irregular, lateral carinae. Propodus extensor margin with row of small spines; flexor margin with 2–5 movable spines, distalmost paired. Dactylus flexor margin with 6 or 7 stout triangular teeth, each bearing slender movable spine.

Ovum: Diameter 1.5 mm.

Etymology. From the Greek treis , three, alluding to the trifid rostrum and presence of three lateral carapace spines.

Remarks. Munidopsis treis n. sp. closely resembles Ms. serricornis in having a trifid rostrum and in lacking epipods on the pereopods. Munidopsis treis is readily distinguished from Ms. serricornis in having three instead of four spines on the lateral margin of the carapace, in having many fewer and distinctly more widely spaced movable spines on the inner margin of the dactyli of the walking legs, in having a relatively longer dactylar apex, and in having a wider anterior margin of the fourth sternite which is in broad contact with the posterior margin of the third sternite. Munidopsis treis consistently bears one anterolateral and two hepatic spines on the carapace. Conversely, Ms. serricornis bears a fourth lateral carapace spine at the base of the branchial groove. Munidopsis treis further differs from Australian specimens of Ms. serricornis in lacking the pair of epigastric carapace spines.

The paratype of Munidopsis treis from Tasmania was misidentified with Ms. serricornis by Baba & Poore (2002) who nevertheless recognised the unusual spination of the dactyli of the walking legs.

Distribution. Tasmania and the Great Australian Bight; 366– 820 m.

Figures

FIGURE 15. Munidopsis treis n. sp., holotype female (16.4 mm), SAM. A, dorsum. B, right lateral. C, right basal antennular segment, ventral. D, right antennal peduncle, ventral. E, right third maxilliped, lateral. F, right cheliped. G, right cheliped, inner distal. H–J, pereopods 2–4. K, sternum. L, telson. Scale A, B, F, H–J = 2 mm, C–E, G, L = 1 mm.