Munidopsis maunga, Schnabel & Bruce, 2006

Schnabel, Kareen E. & Bruce, Niel L., 2006, New records of Munidopsis (Crustacea: Anomura: Galatheidae) from New Zealand with description of two new species from a seamount and underwater canyon, Zootaxa 1172, pp. 49-67 : 55-59

Munidopsis maunga n. sp

( Fig 3 )

Material examined

HOLOTYPE: ♂ (9.9 mm), Macauley volcano caldera, Kermadec volcanic arc, New Zealand, 30°10.09’S, 178°29.89’W, 22 April 2002, 751– 636 m, Stn TAN0205/60 ( NIWA 21138 ) . PARATYPES: 3 ♂♂ (8.7, 8.0, 9.8 mm), same data as holotype ( NIWA 21139 and NMNZ CR.10022) .

Diagnosis

Carapace smooth; with 2 small epigastric spines. Frontal margin oblique; antennal spine present, stronger than anterolateral spine. Lateral margin with 1 spine posterior to anterolateral spine. Rostrum short, triangular, unarmed laterally, horizontal. Abdominal tergites unarmed; telson composed of 12 plates. Eyestalk immovable, eye­spine absent, cornea subglobular. Antennule with 2 terminal and 1 small dorsolateral spine. Cheliped elongate, moderately setose and granulate; merus with 3 longitudinal rows of spines (dorsal, mesial and ventral), continued on carpus by single row of tubercles; propodus unarmed; opposable margins of fingers not gaping. Walking legs sparsely setose; pereopod 2 not overreaching end of pereopod 1; dorsal margin of merus with row of spines along proximal half; carpus only with distal spine on dorsal margin; dactylus about half as long as propodus. P1–4 without epipods.

Description

Carapace: 1.4–1.5 [1.41] times as long as broad (including rostrum), moderately convex laterally. Dorsal surface smooth, covered with a few short striae. Frontal margin oblique. Cervical groove shallow, distinct; carapace unarmed except for paired small epigastric spines. Antennal spine directed anteriorly, larger than anterolateral spine. Anterolateral margin with well­developed spine; lateral margins subparallel, slightly wider posteriorly, with 1 branchial lateral spine directly posterior to cervical groove (followed by serration). Posterior margin unarmed. Rostrum 0.1 times the length of remaining carapace, narrowly triangular, unarmed, horizontal; dorsal surface smooth and sparsely setose; lateral margin smooth. Pterygostomian flap lateral surface with short striae, anterior margin rounded.

Sternum: sternite 3 3.0–3.5 [3.2] times as wide as long; anterior margin bilobed and serrated, with shallow central notch; lateral margins rounded, curved anteriorly; surface smooth. Sternite 4 2.0–2.2 [2.2] times as wide as sternite 3; anterior margin narrowed, shallowly convex; anterior midline shallowly grooved; surface smooth, unarmed. Ridges demarcating sternites 4–7 with rows of setae, surfaces smooth.

Abdomen: tergites smooth, unarmed, sparsely setose; tergite 2 with central transverse groove. Telson 1.3–1.5 [1.5] times as broad as long, composed of 12 plates; lateral margin with row of plumose setae and small spines; uropodal endopods with short rows of spines on surface; lateral margins with a row of spines and plumose setae.

Eyes: smooth, immobile; eye spine absent. Cornea subglobular, 0.7–0.9 [0.7–0.8] as wide as peduncle, with small spine between eye and antennal peduncle.

Antennule: surface smooth; distolateral spine well developed, distomesial spine small; lateral margin swollen, with small dorsolateral spine directed anteriorly.

Antenna: article 1, distomesial and distolateral margins with each short spine (not reaching the end of article 2); article 2 with small distolateral spine; article 3 with blunt distomesial spine.

Maxilliped 3: surface smooth; ischium with small distal spine on extensor margin, 16–23 [19–23] teeth on mesial ridge; merus extensor margin with small distal spine, flexor margin with 2 proximal spines and small distal spine; carpus, propodus and dactylus unarmed.

Pereopod 1 (cheliped): elongate, 2.4–2.7 [2.6] times as long as carapace (including rostrum); surface moderately setose and granulate; ischium with small distodorsal spine. Merus with 3 longitudinal rows of large spines on dorsal, mesial and ventral margins; 4 distal spines. Carpus sparsely tuberculate, including distinct longitudinal row of tubercles, with 4 distal spines, carpus length 0.4–0.5 [0.4] times as long as that of palm. Propodal palm 3.4–4.5 [4.3] times as long as high, sparsely covered with long setae and unarmed. Dactylus 0.4 times as long as propodus; opposable margins not gaping, occlusal margin denticulate.

Pereopods 2–4: surface slightly setose; pereopod 2 anteriorly slightly overreaching base of palm of pereopod 1. Merus with 4–8 [5] spines along proximal half of dorsal crest (including distal spine), 0.8–1.0 times as long as propodus. Carpus with distal spine on dorsal margin and 1 small blunt distal spine on ventral margin. Propodus extensor margin smooth. Dactylus straight; 0.5–0.6 [0.5] times as long as propodus; flexor margin with inclined setae along distal half, with 8–13 [10–13] inclined setae (excluding distal spine). P2–4 meri decreasing in length (and spination) posteriorly.

Epipods: absent from P1–4.

Colour Not known.

Variation The type material contains males of similar size exhibiting only minor morphometric and meristic variation from the holotype.

Remarks

Munidopsis maunga n. sp. can be readily distinguished from all other species in the genus by the combination of the short rostrum, strong antennal and anterolateral spines, single lateral spine posterior to the anterolateral spine, smooth carapace and abdomen (except for the small epigastric spine) and the dorsolateral spines on the antennule.

The morphology of Munidopsis maunga n. sp. is most similar to M. polymorpha Koelbel, 1892 , M. milleri Henderson, 1885 , M. goodridgii Alcock & Anderson, 1899 and M. spinipes MacGilchrist, 1905 . Munidopsis maunga differs from M. polymorpha by the much more convex frontal margin, the pair of epigastric spines, smooth carapace (without small tubercles on the posterior quarter), the width of the propodus of the third maxilliped being narrower and lacking a terminal lobe, and the size of the cheliped (length­width ratio is 5.8 in M. polymorpha and 9.2 in M. maunga ). Munidopsis maunga differs from M. milleri and M. goodridgii in the lack of protogastric, postcervical, cardiac and branchial spines and in having a single spine along the lateral margin of the carapace directly posterior of the cervical groove. The maximum length of the carapace and body of M. maunga (cl = 9.9 mm, body length = 19 mm) is also considerably shorter than those of the similar species M. milleri (cl = 16 mm, body length = 27–33 mm), M. spinipes (body length = 30.5 mm) and M. goodridgii (cl = 21.5 mm) but similar to M. polymorpha (body length = 23 mm).

Munidopsis maunga further differs from M. goodridgii in that the cheliped in M. maunga is much longer in relation to carapace length (2.4–2.7 times cl) compared with M. goodridgii (1.5–2.0). However, M. maunga is described solely from males while M. goodridgii was described solely from females. Therefore, until the degree of sexual dimorphism can be evaluated for both species, the cheliped length as a distinguishing feature should be used cautiously.

Munidopsis maunga can be distinguished from M. spinipes by the lacking rows of spines on the carpus of the cheliped and the unarmed instead of spinose propodus of the cheliped. Also, the meri of the walking legs only have spines along the proximal half of the dorsal margin and the carpus is unarmed except for a distal tooth in M. maunga where M. spinipes has spines almost along the entire margin of the meri and carpi.

Munidopsis polymorpha is known from a shallow anchialine cave system on Lanzarote, Canary Islands. Munidopsis goodridgii , M. milleri and M. spinipes are known only from the Indian Ocean, at depths of 920–1920 metres. No apparently closely related species are known from the Pacific Ocean.

Munidopsis maunga was taken from within the caldera of Macauley volcano within the Kermadec volcanic arc ( Fig. 1 ). The caldera is dotted with hydrothermal vents and small cone volcanoes spanning an area of approximately 10.8 by 8.2 km ( Wright et al. 2006). The exact collecting location of the specimens in relation to the active vents on the caldera is not known but some Munidopsis species are known to occur in immediate proximity to active hydrothermal vents as well as the surrounding slopes covered by hydrothermal and biogenic sediments where they are assumed to be vagrant species. It is assumed that thermal­vent species are opportunists that benefit from the localized and increased chemoautotrophic production ( Macpherson & Segonzac 2005, Martin & Haney 2005).

Distribution Known only from the type locality, the Kermadec volcanic arc, New Zealand; 751– 636 m.

Etymology

Maunga is a Māori word for mountain, with reference to the type locality, the Macauley volcano on the Kermadec volcanic arc, New Zealand.

Figures

FIGURE 1. Station records of the currently known species of Munidopsis (solid symbols) and new records (open symbols) around New Zealand. 250 m and 2000 m bathymetric contours are shown.

FIGURE 3. Munidopsis maunga n. sp., A, B, F, L: holotype, ♂, NIWA 21138, C–E: paratype, ♂, NIWA 21139, G–K: paratype, ♂, NMNZ CR. 10022. A, carapace and abdomen, dorsal; B, carapace and abdomen, lateral; C, anterior part of cephalothorax, showing right antennule, antenna and ocular peduncle, ventral; D, lateral view of right antennule showing dorsolateral spine (arrowed); E, right third maxilliped, lateral; F, sternal plastron; G, left cheliped, dorsal; H–J, right pereopods 2–4, lateral; K, dactylus of right pereopod 2, lateral; L, posterior part of abdomen with uropods and telson. Scale: 2 mm (scale 1 for A, B, F–J, L; scale 2 for C–E, K).