A new squat lobster of the genus MunMopsis Whiteaves, 1874 (Crustacea: Decapoda: Galatheidae) from Taiwan

—A new species of the squat lobster of the genus Munidopsis Whiteaves, M. formosa, is described from deep-water off the northeastern coast of Taiwan. The new species is most similar to M. camelus Ortmann, but differs in having a much broader and less curved rostrum, the posterior carapace ridge generally armed with a pair of submedian spines, only the chelipeds bearing epipods, and having a lighter coloration. The relationships of this new species with some other similar species are also discussed. There are about 150 known species of Munidopsis Whiteaves, 1874 (see Baba 1988), most of which inhabit deep waters (to 5330 m deep) and generally have small eyes as well as a triangular rostrum. To date, only three species, namely M. andarnanica MacGilchrist, 1905, M. cylindrophthalma (Alcock, 1894) and M. latimana Miyake & Baba, 1966, of this genus have been reported from Taiwan (Wu et al. 1998). Recently, several specimens of an undescribed species of Munidopsis from Taiwan were collected off the northeastern coast at a depth of about 500 m. Careful examinations of these specimens showed that they are most similar to M. camelus Ortmann, 1892 from Japan, and differ from other members of the genus in the rostrum being trifid, as well as the second and the third abdominal tergites each armed only with a pair of large submedian spines. Detailed comparison with M. camelus revealed several slight but constant differences between the Taiwanese and Japanese material. The Taiwanese specimens represent a new species described herein. Specimens of the new species are deposited in the National Taiwan Ocean University, Keelung (NTOU), and those used of M, camelus in the personal collection of Prof. K. Baba, Kumamoto University, Japan (KB), The measurements given are of carapace length (cl) excluding rostrum. Munidopsis formosa, new species. Figs, la, c-e, 2a, c, d, 3 Material examined.—Holotype: Taiwan, northeastern coast, Tai-Shi fishing port, ILan County, commercial trawlers, about 500 m, soft bottoms, Aug 1998, 1 S, cl 20.4 mm (NTOU-H 1998-08). Paratypes: Taiwan, northeastern coast, Tai-Shi fishing port, I-Lan County, commercial trawlers, about 500 m, soft bottoms, Apr 1997, 1 6\ cl 27.8 mm (NTOU-P 1997-04); 15 May 1998, 1 6, cl 25.3 mm, 1 ovigerous 9, cl 22.5 mm (NTOU-P 199805-15); 28 Apr 1999, 1 ovigerous $, cl 17.4 mm (NTOU-P 1999-04-28). Description.—Body entirely covered with fine short setae. Rostrum broad, about 2.5 times as long as wide and Vs as long as carapace; more or less horizontal, with tip gently curving dorsad; carinate dorsally, with trifid tip. Carapace (Figs, la, 2a) slightly longer than wide; frontal margin with 1 spine between rostrum and anterolateral spines; lateral margin feebly convex, armed with 4 stout spines (including anterolateral spine) at distal half; 1 pair of epigastric spines present; gastric region moderately convex, bearing row of 1-3 longiVOLUME 113, NUMBER 1 25 tudinal spines; cervical region moderately excavated; cardiac region raised, bearing large median spine; posterior transverse ridge elevated and generally armed only with pair of large submedian spines. Abdomen (Fig. la) with second and third tergites each having pair of large submedian spines. Telson (Fig. 2d) subdivided into 10 plates; lateral margins fringed with dense setae (very thick in male), posterior margin with plumose setae. Eyes small, lacking dark pigments, movable, extending to about middle of rostrum. A large spine present between eye and antenna. Basal antennular segment (Fig. lc) bearing 2 strong distolateral spines, with distal one slightly larger. Antennal peduncle (Fig. Id) with basal segment bearing distomesial and distolateral spines (distomesial one very strong and long), other segments spineless. Merus of third maxilliped (Fig. le) longer than ischium, flexor margin bearing 3 spines, diminishing in size anteriorly, extensor margin armed with large distal spine. Third thoracic sternite narrowing posteriorly, anterior margin concave; fourth thote much wider, about 3 times as wide as preceding (Fig. 2c). Chelipeds subequal, long and robust (massive in largest male), surface covered with long setae; merus long and with some large spines; carpus short, with spines mainly restricted at distal margin; palm longer than finger and without large spines (but sharply granular in the largest male); fingers not perfectly gaping, inner margins bearing some intermeshing teeth, outer margins nearly straight except at tips (that of fixed finger becoming convex in largest male). Walking legs robust, similar, all covered with setae. First walking leg having merus with large distodorsal and distolateral spines, and some dorsal spines; carpus generally armed with 2 distodorsal spines; propodus nearly straight, more than 5 times as long as wide; dactylus much shorter than propodus, distally curving ventrad, ventral margin minutely dentate. Epipod present only on chelipeds. Eggs subspherical, about 0.5 mm in diameter. Coloration (Fig. 3).—Body pale orange to orange, with color of females generally deeper. Rostrum except tip, pale orange or whitish. Fourth or fifth abdominal segments to tailfan from pale orange to pale white posteriorly. Eyes pale orange or nearly whitish. Antennules same color as body but antennal flagella orange red. Cervical groove and cardiac depressions sometimes whitish. Ventral surface whitish except mouth parts and chelipeds pale orange. Size.—Largest male and female cl 27.8 mm and 24.6 mm respectively. Smallest ovigerous female cl 17.4 mm. Distribution.—So far known only from the northeastern coast of Taiwan, at depths of about 500 m. Type locality.—Taiwan, northeastern coast. Remarks.—The present form is closely related to Munidopsis camelus Ortmann, 1892 from Japan and can be readily separately from the other species of the genus by the rostrum being trifid, as well as the second and third abdominal tergites each armed with a pair of large submedian spines. Careful comparisons between M. camelus (1 6 cl 23.2 mm, 1 9 cl 21.5 mm, off Hayama, Sagami Bay, Japan, lobster pot, Oct 1987, H. Ikeda coll. deposited at Kumamoto University Faculty of Education; also see Miyake & Baba 1967) and the Taiwanese material revealed the following differences. The anterior three pereiopods bear distinct epipods in the Japanese material but usually only the chelipeds have epipods in the Taiwanese specimens. However, in one of the Taiwanese specimens (NTOU-P 1997-04), a distinct epipod is also present on the left first walking leg. It seems that the presence or absence of epipod are not always consistent as previously thought for galatheids. Nevertheless, further differences between the Taiwanese and Jap26 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Fig. 1. a, c-e: Munidopsis formosa, new species, 6 holotype cl 20.4 mm, N. E. Taiwan (NTOU-H 199808). b: M. camelus Ortmann, 1892, o* cl 23.2 mm, Sagami Bay, Japan (KB), a, carapace and anterior abdominal somites, dorsal view; b, carapace; c, left basal antennular segment, ventral view; d, left antennal peduncle, ventral view; e, basal segments of endopod of right maxilliped, ventral view. Scale bars = 5 mm. VOLUME 113, NUMBER 1