Munidopsis lauensis Baba

Lin, Chia-Wei, Tsuchida, Shinji, Lin, Saulwood, Berndt, Christian & Chan, Tin-Yam, 2013, Munidopsis lauensis Baba & de Saint Laurent, 1992 (Decapoda, Anomura, Munidopsidae), a newly recorded squat lobster from a cold seep in Taiwan, Zootaxa 3737 (1) : -

Munidopsis lauensis Baba & de Saint Laurent, 1992

( Figs. 1 , 2 )

Munidopsis lauensis Baba & de Saint Laurent, 1992: 326, fig.3 (type locality: Lau Basin, near Fiji).—Baba 2005: 290.—Martin & Haney 2005: 478.—Cubelio et al. 2007b: 516, fig. 3.

Material examined.— Valufa Ridge, Hine Hina, Lau Basin, BIOLAU 89, stn BL01, 22°32’ S, 176°43’W, 1750 m, 13 May 1989, 1 male CL 7.8 mm, 1 female CL 8.8 mm, paratypes (MNHN Ga 2353).

Taiwan, southwestern coast, Formosa Ridge, 22°6.9’N, 119°17.1’E, TV guided grab (TVG), 1136 m, April 2013, 3 males 12.0–13.0 mm CL (NTOU A01415).

Description.— Body smooth. Carapace exclusive of rostrum about 1.2 times longer than broad, moderately arched from side to side. Rostrum triangular, carinate dorsally, nearly straight or feebly up curve, lateral margin often with fine serration. Cervical groove distinct. Frontal margin strongly oblique; outer-orbital spine very small or obsolescent. Gastric region somewhat dilated, with 2 anterior transverse rugae. Anterior branchial region with rugae, with distinct anterolateral spine followed by a few small teeth. Posterior margin concave, preceded by slightly elevated submarginal ridge.

Thoracic sternites smooth; third sternite posteriorly narrowed, anterior margin bearing 2 lobes, anterolateral angle ending in blunt but distinct process on each side.

Abdomen smooth; second to fourth segments each with rounded transverse ridges. Telson composed of 10 plates.

Eyes not movable; well exposed smoothly ovate cornea cupped within broad-based ocular peduncle; peduncle extended anteriorly as a strong mesiodorsal spine bearing straight forward lateral margin and accompanied by small mesioventral spine; cornea relatively large.

Basal article of antennule unarmed on ventrodistal margin, having distolateral spine much larger than dorsolateral.

Third maxilliped with relatively broad endopod, ischium nearly half as long as merus, mesial ridge with 23 or 24 denticles. Merus with small spine (often obsolescent) on flexor margin, and another small distolateral spine (often obsolescent) on extensor margin.

Chelipeds 1.7–1.8 times as long as postorbital carapace length; with weakly developed, setose rugosities somewhat tuberculate in longitudinal lines; long plumose setae more dense ventrally along distomesial margin of merus, distal margin of carpus, and mesial margin of palm. Ischium with small distomesial spine. Merus twice as long as carpus, with distinct distoventral and distomesial spines, mesial margin bearing 3–5 spines. Carpus with distodorsal spine and mesial marginal spine at widest portion about one-third from distal end. Palm as long as finger, 1.1 times as long as broad, mesially with few tubercles often pronounced into spiniform processes but occasionally obsolescent. Fingers distally spooned, having prehensile edge crenulate.

First walking leg not reaching end of cheliped. Merus with dorsal spines usually small, often tuberculate; ventral margin with obsolescent tubercular processes. Carpus with distinct distodorsal spine, dorsolaterally with feebly tuberculate low ridge parallel to dorsal margin. Propodus obliquely flattish, dorsal surface bordered by rounded longitudinal ridges. Dactylus somewhat uniformly broad, flexor margin nearly straight, with 11–16 teeth decreasing in size proximally, each accompanied by seta-like spine; ultimate tooth not remote from curved corneous terminal claw.

Epipods absent in all pereopods.

Coloration.— Body entirely ivory white. Eyes pale yellow to pale orange. Setae grayish brown.

Distribution.— Previously reported from hydrothermal vents in the South-West Pacific at the Manus Basin in Papua New Guinea, North Fiji Basin and Lau Basin near Fiji, and Brothers Seamount in the Kermadec Arc, at depths of 1649–2000 m; now significantly extended geographically to southwestern Taiwan from cold seeps at 1136 m deep.

Remarks.— The Taiwanese specimens agree well with the original description of the species given by Baba & de Saint Laurent (1992), except for armature at the front margin of the carapace and the cheliped. The type series has the carapace frontal margin armed with an acuminate outer-orbital spine (or antennal spine) immediately lateral to the eyestalk and this is also illustrated in Cubelio et al. (2007b: fig. 3). The outer-orbital spine, however, is represented by a small angular process in the Taiwanese material ( Fig. 1 A). Moreover, the Taiwanese specimens have the merus of the cheliped armed with 3–5 distinct spines on the mesial margin (Fig. E). However, the type series has the merus unarmed along the mesial margin.

To evaluate if the above differences are significant, DNA barcoding was employed to compare the COI sequences (657bp) of the different populations. Although the attempt to sequence the COI gene in the two paratypes examined failed, the COI sequences between the Taiwanese material (GenBank no. KF774316 ) and those from the Brothers Seamount, Manus and Lau Basins reported in Cubelio et al. (2007c, GenBank nos. EF 157850 , 157851, 1587852, 157853) are nearly identical (with only 0.3% sequence divergence). Thus, it can be concluded that the Taiwanese material is indeed M. lauensis and the variations observed above likely represent

Figures

FIGURE 1. Munidopsis lauensis Baba & de Saint Laurent, 1992, Taiwan, male CL 12.5 mm (NTOU A 01415). A, carapace, dorsal. B, right antennules, antenna and ocular peduncle, ventral. C, anterior part of sternal plastron. D, endopod of right third maxilliped, setae omitted, lateral. E, right cheliped, lateral. F. dactylus of right first walking leg, lateral. Scale bars = 1 mm.

FIGURE 2. Munidopsis lauensis Baba & de Saint Laurent, 1992, Taiwan, male CL 12.5 mm (NTOU A 01415). Fresh specimen, dorsal view.