Uruma ourana Naruse, Fujita & Ng, 2009, n. sp.
Creators: name: Naruse, Tohru
name: Fujita, Yoshihisa
name: Ng, Peter K. L.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pinnotheridae
Uruma
Uruma ourana

description: Uruma ourana n. sp.
(Figs. 1–4)
Material examined. Holotype, male, 4.2 × 9.2 mm, RUMF-ZC-907, Oura Bay Okinawa, Ryukyu Islands, Japan, 8 m, from a tube of unidentified, possibly polychaete, worm, coll. M. Obuchi, 28 Jul. 2007.
Comparative material. Pinnixa penultipedalis Stimpson, 1858: 1 female, 1.8 × 3.6 mm, ZRC 1970.8.4.10, Nhatrang Bay, Vietnam, coll. Gallardo, 1954. Pinnixa sayana Stimpson, 1860: 2 males, 2.1 × 4.4 mm, 2.5 × 5.6 mm, ZRC 2008.0152, Maceió, Brasil, coll. 1990.
Description of holotype. Carapace (Fig. 1 a) wide, trapezoidal, widest at anterolateral margin, CW 2.19 times CL; dorsal surface smooth, glabrous, flat (Figs. 2 a, 3a), anterior, posterior quarters of carapace sloping downwards, regions poorly defined, epibranchial regions with 3 low protuberances, cervical groove very shallow, H-shaped gastric groove distinct, cardiac region laterally demarcated by grooves. Anterolateral margin strongly produced, continuous to posterolateral margin, proximal three-quarters of carapace gently convergent posteriorly, margin cristate from proximolateral angle to just mesial to anterolateral angle, not continuing to external orbital end (Fig. 3 a); epimeral suture just inferior to carapace margin proper. Front narrow, 0.14 times CW, deflexed medially, deflexed part triangular (Fig. 3 a). Orbit oblique, mesial part of supraorbital margin distinctly placed more posteriorly than external orbital end; orbital margins entire, outer part granular, infraorbital margin mesially ending as sharp tooth (Figs. 2 a, 3a). Epistome short, medially sunken, posterior margin with sharp median tooth. Milne Edwards’ aperture distinct, upper margin of aperture rimmed, anterior margin of rim fringed with long setae. Eyes (Figs. 2 a, 3a) short, stout, mobile, fully occupying orbit. Antennule small, folded somewhat obliquely. Antenna (Fig. 3 a) entering orbit, flagellum short, distal segment reaching external orbital end. Third maxillipeds (Figs. 2 b, 3b) convering about fourfifths of trapezoidal buccal cavern; ischium produced proximolaterally, mid-length slightly longer than merus; merus completely articulated from ischium by horizontal suture, palp (carpus, propodus, dactylus) attached to medial concave part of distal margin of merus, each segment of palp connected to distal ends of respective proximal segments; exopod broad proximally, reaching distal third of merus, flagellum long, exceeding mesial margin of merus.
Thoracic sternites 1/2 completely fused, sternite 1 tooth-like, directed dorsally at proximal end of buccal cavern; sternites 2/3 demarcated by deep groove; sternites 3/4 fused, lateral parts marked by very shallow depressions, pits; sternites 4–8 demarcated by narrow lateral grooves at outside of sternal cavity, grooves ending at lateral part of sternal cavity; sternal cavity depressed medially, no clear longitudinal groove (Fig. 2 b, c). Penis (Fig. 2 c) distinctly sternal, opening at anterior margin of sternite 8, adjacent to posterior margin of sternite 7.
Chelipeds (Fig. 1) equal, short. Merus triangular in cross section; ventral, dorsal margins with setae, dorsal margin with large subdistal lobe triangular in distal view (Fig. 3 c). Carpus (Fig. 3 c) suboval, outer surface covered with short setae, no inner angle. Chela (Fig. 3 d) small, as long as merus, short setae covering ventral half of palm to proximal part of cutting edge of immovable, movable fingers in outer, inner surfaces; cutting edge of immovable finger concave proximally, distally blade-like, tip hooked; movable finger straight, tip slightly hooked, cutting edge blade-like, slightly dentate proximally.
P2 to P4 similar in shape, P4 (Fig. 3 e) longest, combined length of merus to dactylus of P4 1.08 times CW; merus stout, long, merus of P4 0.66 times CW, about two-thirds of combined length of respective carpus to dactylus; anterior, posterior margins subparallel, anterior portion covered with short setae, proximal half of anterior margin lined with granules, posterior margin scattered with long setae. Carpus longer than propodus; carpus, propodus with flattened outer surface, covered with short and long setae; distoflexor angle of propodus with a pair of short, sharp claws (Fig. 3 f). Dactyli very short, claw-like (Fig. 3 e, f). P5 (Fig. 3 g) short, reaching only proximal half of P4 merus. Ischium with flexor surface extended distally, with subdistal sharp tooth. Merus slightly longer than combined length of respective carpus to dactylus, posterior margin with strong proximal tooth. Carpus as long as propodus, propodus somewhat compressed, distoflexor teeth of propodus, dactylus similar to those of anterior legs.
All abdominal somites, telson free (Fig. 4 a); first somite widest, thoracic sternite 8 exposed when abdomen closed; first two somites shorter than other somites, lateral margins of somite 3 to telson gradually converging distally; telson reaching imaginary line joining proximal half of cheliped coxae. G1 (Fig. 4 b) straight, slender, subparallel in about proximal five-sixths, distally tapered, incurved. G2 (Fig. 4 c) short, about one-fifth length of G1.
Etymology. The species is named after Oura Bay, Okinawa, where this interesting the crab was discovered. The name is used as a noun.
Habitat. The holotype of Uruma ourana n. sp. was collected from a tube, presumably made by a polychaete worm, from a depth of 8 m. The tube was collected from a gentle slope of a mixed rudaceous and muddy sediments. The holotype was seen from the opening of the tube (M. Obuchi, personal communication). A large colony of acorn sea pens (Cavernulariidae) was also observed on this site. Subsequent attempts to collect more specimens from the same locality were not successful.
The holotype was partially covered with calcium deposits (left side of the intestinal region in Fig. 1). Several individuals of encrusting foraminiferans were also observed on the surfaces of the carapace and the ambulatory legs (three individuals in the left epibranchial region in Fig. 1).
description: Published as part of Naruse, Tohru, Fujita, Yoshihisa & Ng, Peter K. L., 2009, A new genus and new species of symbiotic crab (Crustacea: Brachyura: Pinnotheroidea) from Okinawa, Japan, pp. 59-68 in Zootaxa 2053 on pages 62-66, DOI: 10.5281/zenodo.186636