Solenotheres prolixus Ng & Tri, 2010, new species
Creators: name: Ng, Peter K. L.
name: Tri, Ngo Van
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Pinnotheridae
Solenotheres
Solenotheres prolixus

description: Solenotheres prolixus, new species
(Figs. 1–3)
Material. Holotype ovigerous female, cl 4.40 mm, cw 6.58 mm (ZRC), from Solen corneus, intertidal area, Vinh Chau town, Vinh Chau District, Soc Trang Province, southwestern Vietnam, V. T. Ngo, 16 January 2010.
Description of holotype female. Carapace distinctly broader than long, cw 1.5 times cl; dorsal surface smooth, glabrous, regions poorly defined; entire surface with numerous distinct chromatophores; anterior surface gently raised medially but without distinct ridge, lateral, posterior surfaces gradually sloping (Fig. 1). Front short, 0.18 times cw, not produced anteriorly, not visible in dorsal view, deflexed with median part triangular (Figs. 1 A, 2A, B). Anterolateral margin rounded, not cristate (Fig. 1 B). Orbit very small, completely filled by mobile eye, not visible in dorsal view; cornea pigmented (Figs. 1 B, 2B). Antennular fossa larger than orbit; antennules folding almost transversely (Figs. 1 B, 2B). Antennal flagellum very short; first 2 segments fused to epistome (Fig. 2 B). Posterior margin of epistome triangular with concave lateral margins (Fig. 2 B).
MXP3 with ischium, merus completely fused without trace of suture, ischiomerus ovate, about half as wide as long; inner, outer margins convex (Fig. 2 C). Carpus shorter than propodus (Fig. 2 C). Propodus spatuliform, longer than wide, distally rounded (Fig. 2 C, D). Dactylus elongated, spatuliform, subequal to propodus, inserted just before base of propodus (Fig. 2 C, D). Exopod barely visible in situ, almost completely covered by ischiomerus except for base, with gently convex inner, outer margins; flagellum 3-segmented, distal segment with long setae (Fig. 2 C).
Chelipeds symmetrical (Fig. 1 A). Palm relatively slender, long, ventral margin concave with scattered setae (Figs. 1 A, C, 2E). Merus short, unarmed; carpus elongated, subequal in length to merus, inner margin with long setae (Fig. 1 A). Dactylus, pollex gently curved, crossing distally; cutting edge of pollex with low submedian tooth, distal denticles; cutting edge of dactylus with well developed sub-basal tooth (Fig. 2 E).
Ambulatory legs (P2–5) generally similar in form; P2, 4, 5 symmetrical from left to right, margins with scattered setae; right P3 with merus, propodus, dactylus proportionately longer than left P3 (Figs. 1 A, 3B, E). Relative lengths in decreasing order P3>P4>P2>P5 (Fig. 3 A–D). Merus, carpus, propodus unarmed, smooth; anterior half of dorsal margins of meri with relatively dense long setae; postero-ventral margins of propodi with setae of varying lengths, density (Figs. 1 A, C, 3). Dactyli relatively stout, falcate with sharp apices; subequal except for relatively longer dactylus of right P3 (Figs. 1 A, C, 3); ventral margins with scattered short setae (Fig. 1 A, C).
Abdomen subcircular, very broad, completely covering thoracic sternum, almost reaching base of MXP3; with 6 free somites plus telson; somite 5 widest; somite 1 very narrow longitudinally; telson broadly triangular with gently sinuous lateral margins (Figs. 1 C, 2F).
Colour. The colour in life of the carapace was white with an orange tinge, especially in the median parts; pereopods white; setae near base of legs light brown.
Etymology. Derived from the Latin prolixus for “broad,” alluding to the relative proportions of the carapace of the species.
Host. The type specimen was collected from the razor clam Solen corneus which had been purchased from the market in the town of Vinh Chau. The razor clams were collected in the immediate area on the intertidal beach zone, in sand, at depths of 30 to 40 cm at low tide.
Remarks. See discussion for genus. As there is only one specimen of Solenotheres prolixus, new species, it is not possible to ascertain if the diagnostic asymmetrical P3 of the species is natural or anomalous. Certainly there is no indication that the legs have been damaged before or it is an abnormal regrowth of a previously lost or injured pereopod.
Distribution. Presently known only from the type locality in Vietnam.
description: Published as part of Ng, Peter K. L. & Tri, Ngo Van, 2010, Solenotheres prolixus, a new genus and new species of pinnotherid crab (Crustacea: Decapoda: Brachyura) associated with the razor clam, Solen corneus Lamarck, 1818 (Solenidae) in Vietnam, pp. 61-68 in Zootaxa 2570 on pages 63-67, DOI: 10.5281/zenodo.197368