Munidopsis debilis Henderson, 1885

Published, First, 2007, Species of the genus Munidopsis Whiteaves, 1784 from the Indian and Pacific Oceans and reestablishment of the genus Galacantha A. Milne-Edwards, 1880 (Crustacea, Decapoda, Galatheidae), Zootaxa 1417, pp. 1-135 : 60-63

Munidopsis debilis Henderson, 1885

( Figs. 28, 29, 55H)

Elasmonotus debilis Henderson, 1885: 417 ; 1888: 165, pl. 18, figs. 4, 4a (in part, only station 210, the Philippines). Munidopsis (Elasmonotus) debilis .— Tirmizi, 1966: 215, figs. 29c–e, 30 (selection of lectotype).

Munidopsis debilis .— Baba, 2005: 287.

Material examined. Philippines, off Mindanao , CHALLENGER, Stn 210, 694 m: 1 M ca. 7.0 mm (broken) (lectotype, BMNH) . New Caledonia, BATHUS 2, Stn 741, 700– 950 m: 1 ovig. F 8.9 mm (MNHN- Ga5663).— Stn 762, 620– 700 m: 1 M 8.5 mm ( MNHN).—Stn 764, 560– 570 m: 1 M 11.3 mm (MNHN- Ga5664). HALIPRO 1, Stn 858, 1000–1120 m: 1 ovig. F 8.6 mm (MNHN-Ga5665). BATHUS 4, Stn 893, 600– 620 m: 1 ovig. F 8.9 mm (MNHN-Ga5666) . Vanuatu, MUSORSTOM 8, Stn 1027, 550– 571 m: 1 ovig. F 11.5 mm (MNHN-Ga5667).—Stn 1076, 1100–1191 m: 1 ovig. F 8.8 mm (MNHN-Ga5668) . Fiji, MUSORS- TOM 10 , Stn 1335, 729– 753 m: 1 ovig. F 9.6 mm ( MNHN).—Stn 1342, 650– 701 m: 3 M 6.5–8.5 mm (MNHN-Ga5669).—Stn 1348, 353– 390 m: 1 F 8.4 mm (MNHN-Ga5670). BORDAU 1, Stn 1401, 600– 648 m: 3 M 7.7–8.4 mm ( MNHN) .

Description. Carapace dorsally spineless, bifurcated cervical groove slightly distinct, bearing weak interrupted transverse ridges more distinct on epigastric region and posterior half of carapace, ridges with fine short setae; gastric region convex, circumscribed, cardiac region slightly convex, depressed in front of slightly elevated transverse ridge. Rostrum lanceolate, barely half as long as remaining carapace, maximum width 0.3 carapace breadth, with longitudinal dorsal groove, slightly deflexed, sometimes upcurved distally, maximum width one-quarter carapace breadth,; lateral margins carinated and usually convex. Front margin slightly convex on mesial half, lateral half transverse, depressed below level of mesial half. Lateral margins subparallel, not cristate, each constricted at end of cervical groove, anterolateral angle unarmed. Posterior transverse ridge slightly elevated, uninterrupted and unarmed.

Sternum elongate, slightly longer than wide, maximum width at level of sternite 7. Sternites feebly granulated; sternite 3 moderately broad, 3 times wider than long, anterior margin divided into 2 lobes by deep median notch; lateral margin of each lobe convex, with small granules, posterior border broadly contiguous with anterior margin of sternite 4; sternite 4 narrowly elongate anteriorly; surface depressed in midline, smooth; greatest width 2.3 times that of third sternite.

Abdominal segments spineless; segments 2–4 with two slightly elevated transverse ridges; posterolateral lobes of segment 6 slightly overreaching nearly transverse posteromedian margin. Telson divided into 12 plates, posterior plates each as long as broad.

Eye small, movable, not reaching midlength of rostrum; cornea subglobular, moderately small, as long as remaining eyestalk; distinct spine ventral to front margin between ocular and antennal peduncles.

Basal article of antennular peduncle with granulated distomesial process, strong distolateral and distoventral spines.

Antennal peduncle having basal article with acute distomesial and rounded distolateral processes; article 2 with distolateral acute process; article 3 distolaterally produced.

Mxp 3 ischium slightly shorter than merus, measured along extensor margins; merus with 2 flexor marginal spines, distal one subequal to or slightly larger than proximal spine, extensor margin with distal spine.

P1 subcylindrical, setose along mesial and lateral margins, with small granules and short striae, twice as long as carapace; merus with small distomesial and distolateral spines; carpus nearly twice as long as high, with small distomesial and distolateral spines; chela spineless; palm 1.3 as long as carpus, fingers as long as palm, not gaping, distally bearing intermeshing teeth; fixed finger without denticulate carina on distolateral margin.

P2–4 barely setose, relatively slender, slightly compressed, 3 distal articles subcylindrical; meri slightly depressed and decreasing in length posteriorly, dorsal margin feebly carinate, ventral margin granulated. P2 barely reaching end of P1 carpus. P2 merus 2.8 times as long as high, nearly 3 times length of carpus and 1.5 times length of propodus; carpus with small distal spine on dorsal margin and carinated along lateral side; propodus 3.3 times as long as high and 1.5 times length of dactylus; dactylus ending in curved claw preceded by 5 or 6 proximally diminishing spines on nearly straight flexor margin, each spine bearing short seta, ultimate tooth closer to penultimate one than to end of terminal claw.

Epipods absent from P1–4.

Colour. Posterior half of carapace and abdomen light brown or grey; anterior half brown; pereiopods brown. Corneae orange.

Remarks. Munidopsis debilis was described by Henderson (1885, 1888) from two males, one collected in the Philippines (Stn 210) and another in the Fiji Islands (Stn 173). Tirmizi (1966) pointed out that the two specimens belonged to different species. She selected the male from the Philippines as the lectotype, following the notes made by Henderson in the original description and illustrations.

Munidopsis debilis belongs to the group of species with the carapace unarmed and abdomen smooth, rostrum triangular or lanceolate, with longitudinal dorsal groove, P1 longer than P2, front margin without antennal spine, eye with ocular peduncle movable, corneae oval and unarmed, and carapace not cristate on lateral margin.

The closest relative is M. cylindropus Benedict, 1902 (see also Baba 2005), from Japan and the Philippines. The two species can be separated by the presence of a distinct mesial marginal spine proximal to midlength of the P1 merus in M. cylindropus , whereas this spine is absent in M. debilis . Furthermore, the corneae are longer than the remaining eyestalk in M. cylindropus , being subequal in length in M. debilis .

The rostrum of the specimens collected at the deepest stations (HALIPRO 1, Stn 858 and MUSORSTOM 8, Stn 1076) are more spiniform than in other material; this difference is regarded as intraspecific variation.

Distribution. The Philippines, New Caledonia, Vanuatu and Fiji, between 353 and 1191 m.