Xenocrate peculiaris Ng & Castro, 2007, new genus
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Euryplacidae
Xenocrate
Xenocrate peculiaris

description: Xenocrate peculiaris, new genus, new species
(Figs. 1 –6)
Material examined: Holotype: male, cl 34.0 mm, cw 39.1 mm (NMCR), in tangle nets, Maribohoc Bay, 100– 300 m, coll. J. Arbasto, between Nov. 2003 and April 2004. Paratypes: 1 female, cl 36.9 mm, cw 42.2 mm (ZRC), station L45, Maribohoc Bay, 80–90 m, coll. J. Arbasto, 3 July 2004; 1 male, cl 39.6 mm, cw 45.8 mm (ZRC), in tangle nets, Maribohoc Bay, 100–300 m, coll. J. Arbasto, between June 2004 and May 2005. All localities from Panglao, Bohol, Philippines.
Description of holotype male. Carapace subhexagonal; dorsal surface finely granular, strongly convex, without clear indication of regions, short low ridges on hepatic region; grooves shallow except for gastro-cardiac ones (Fig. 1 A, B). Front lamellar, truncate, marked by distinct median notch; frontal, supraorbital margins separated deep notch; orbits relatively wide, oval, not expanded laterally; supraorbital margins short, slightly curved, with 2 small notches (Fig. 1 B, C). Suborbital margin with large, blunt inner tooth on inner edge, separated from small tooth on outer edge by deep cleft (Figs. 1 C, 2A). Anterolateral margins curved with 2 teeth, excluding low external orbital tooth which is short, triangular; first tooth larger, triangular; second tooth directly anteriorly, relatively more slender, sharper than first tooth (Fig. 1 A, B). Posterlolateral margins gently convex, convergent; posterior carapace margin gently sinuous (Fig. 1 A, B). Basal antennal article short, closed by extension of carapace margin, thus distalmost (third) article reaches front (Fig. 1 C). Eye peduncles relatively short, cornea spherical, only slightly expanded distally; filling up almost entire orbit (Fig. 1 C). Posterior margin of epistome strongly lobulated; lateral lobes large, subtruncate, separated from median part by a deep fissure; median part with 3 lower lobes separated by broad, low cleft, with median lobe broadly triangular (Fig. 1 C). Anterior margin of endostome well demarcated from buccal cavern, endostomial ridges low but clearly defined. Third maxillipeds completely close buccal cavern; ischium rectangular with deep submedian sulcus; merus relatively squarish but anteroexternal part prominently expanded, rounded, auriculiform; exopod long, reaching to just before anterior edge of merus with long flagellum (Fig. 2 A). No visible stridulating mechanism.
Thoracic sternum relatively wide; anterior end of sterno-abdominal cavity reaching anterior margin of sternite 4 (Figs. 2 B, 3A). Press-button of abdomen-locking mechanism with medium-size knob on anterior edge of thoracic sternite 5 (Fig. 3 A) pairing with shallow socket on underside (ventral surface) of abdominal somite 6. Thoracic sternites 1, 2 completely fused; suture 2/3 deep; suture 3/4 shallow, medially interrupted; sutures 4/5, 6/7, 7/8 interrupted medially, 5/6 complete (Figs. 2 B, 3A, 5C). Lateral parts of episternites 4–7 expanded, that of episternite 7 most prominent, covering part of sternite 8, coxa of P5; sternite 8 without supplementary plate, not visible when abdomen closed (Fig. 2 C, D). Penis effectively coxo-sternal, not calcified, with small, soft papilla, very broad, soft proximal expansion (Fig. 3 C).
Cheliped stout, long; surfaces relatively smooth (Fig. 1 A); merus without carinae, with low subdistal tooth on dorsal margin (Fig. 1 A); carpus with acute tooth on inner margin (Fig. 1 A); fingers relatively slender, slightly less than half propodus length, tips darker in colour (Fig. 3 C). P2–P5 long, slender, P4 longest (Fig. 1 A); merus, carpus, propodus slender; dorsal margins unarmed; margins of dactylus, propodus prominently setose; dactylus slender, that on P5 relatively broader, subspatuliform.
Abdomen with 6 freely-movable somites, elongated, transversely narrow, much longer than wide (Fig. 2 B, C); somites 4–6 sharply decreasing in length; somite 3 widest, somite 6 longer than wide, somite 5 wider than long (Fig. 2 B); somites 3–5 trapezoidal (Fig. 2 B, C); somite 3 subtrapezoidal (Fig. 2 C); somites 2, 3 cover entire space between P5 coxae, thoracic sternite 8 not visible when abdomen closed(Fig. 2 C); somite 1 very narrow longitudinally, much more so than somite 2, only partially covered by posterior carapace margin (Fig. 3 C, D). Telson acutely triangular, longer than broad (Fig. 2 B). G1 very slender, relatively straight, bordered by numerous denticles of varying sizes on distal half, pointed apex (Fig. 4A–C); G2 short, less than 1/3 G1, distal part (flagellum) short, apex pointed (Fig. 4D, E).
Paratype female. Anterolateral teeth relatively more prominent than male (Fig. 5 A); posterolateral margin less convex (Fig. 5 A). Female abdomen with 6 freely-movable somites; telson relatively narrow, leaving distal portion of all thoracic sternites visible (Fig. 5 B). Vulva of mature females ovoid, extending from suture 5/6 but not reaching 6/7 suture, operculum absent but vulva with thickened margins (Fig. 5 C).
Etymology. The name is derived from the Latin for peculiar, alluding to the unusual suite of characters of the species.
Remarks. See genus discussion.
Distribution. Known only from the Philippine Islands. Depth: 80– 300 m.
description: Published as part of Ng, Peter K. L. & Castro, Peter, 2007, On a new genus and species of euryplacid crab (Crustacea: Decapoda: Brachyura: Goneplacoidea) from the Philippines, pp. 43-53 in Zootaxa 1549 on pages 45-46, DOI: 10.5281/zenodo.178057