Samadinia longispina Ng & Forges, 2013, n. sp.
Creators: name: Ng, Peter K. L.
name: Forges, Bertrand Richer De
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Epialtidae
Samadinia
Samadinia longispina

description: Samadinia longispina n. sp.
(Figs. 1, 2, 3A, E, 4 A–D)
Material examined. Holotype: male (25.3 × 17.9 mm) (MNHN-IU-2011-4190), stn CP 3381, 15°41’S 146°56’W, French Polynesia, south of Society Islands, Tarava Seamounts, 830–988 m, coll. TARASOC, RV Alis, 5 October 2009. Other material: EXBODI: 1 ovigerous female (12.9 × 8.9 mm) (MNHN-IU-2013-1678), stn CP 3911, Astrolabe reefs, northern New Caledonia, 19°50’S 165°33’E, 680–802 m, coll. RV Alis, 23 September 2011. — 1 female (13.8 × 9.6 mm) (ZRC ex MNHN-IU-2013-1688), stn CP 3911, Astrolabe reefs, northern New Caledonia, 19°50’S 165°33’E, 680–802 m, RV Alis, 23 September 2011.
Diagnosis. Dorsal surface of carapace with numerous small rounded granules (Figs. 1 A, 3A). Pseudorostral spines long, curved, diverging (Figs. 1 A, 3A). Supraocular eave narrow forming acute sharp tooth, directed anteriorly; postocular tooth acutely triangular (Figs. 1 A, B, 3A). Hepatic spine long, sharp, subequal in length to branchial spine, directed sublaterally (Figs. 1 A, 3A). Lateral margin with numerous small rounded granules, with long branchial spine directed laterally (Figs. 1 A, B, 3A). Basal antennal article broad, with 2 low distal teeth (Figs. 1 C, 2A). Ambulatory legs, especially meri, relatively long (Figs. 1 A, 3A). Surface of female abdomen with raised median ridge of tubercles. G1 gently sinuous with 3 folds (Fig. 4 A?C).
Description. Carapace pyriform; dorsal surface with regions poorly defined, uniformly covered by rounded granules, without tubercles or spines; cardiac region elevated (Figs. 1 A, B, 3A). Pseudorostral spines long, slender, straight, cylindrical in cross-section, prominently diverging outwards (Figs. 1 A, 3A). Supraocular eave short, forming acute sharp tooth, directed anteriorly; postocular tooth relatively short, acutely triangular, tip rounded. Hepatic spine long, straight to slightly curved, directed laterally to sublaterally (Figs. 1 A, 3A). One long lateral spine, directed laterally, subequal in length, subparallel to hepatic spine (Figs. 1 A, 3A). Intestinal region with a large rounded tubercle just before posterior carapace margin (Figs. 1 A, 3A).
Ocular peduncle short, with granular tooth on upper border; cornea round, fully pigmented (Figs. 1, 3A). Suborbital margin confluent with lateral margin of basal antennal article (Fig. 2 A, B). Basal antennal article longer than broad, with 2 low distal teeth; third, fourth articles cylindrical, flagellum relatively short, slender, positioned just outside orbit (Figs. 1 C, 2B, C). Antennules folding vertically (Fig. 2 B). Epistome longitudinally narrow; posterior margin crenulated (Fig. 2 B). Pterygostomial area smooth, separated from sub-branchial region by row of 4 large, rounded granules (Fig. 2 A). Third maxillipeds completely covering buccal cavity when closed; surfaces smooth, covered by short pubescence; ischium wider distally than proximally, with distinct, broad median sulcus; merus quadrate, anterolateral margin auriculiform; exopod relatively stout, reaching to just before distal edge of merus, with long flagellum (Fig. 2 A, C).
Chelipeds subequal, chelae not inflated; merus trigonal in cross-section, with distal tooth on dorsal margin; carpus short, with dorsal surface somewhat flattened; surface of palm slightly rugose; fingers subequal in length to palm, distal portion of cutting margin with distinct teeth, proximal portion uneven to serrulate (Figs. 1 A, 2D, 3A). Ambulatory legs relatively long, slender; first leg longest, fourth leg shortest; surfaces with scattered short setae; meri unarmed; carpus short with lateral sulcus; dactylus tapering, surface with dense short setae except for corneous tip (Figs. 1 A, 3A).
Surface of thoracic sternum covered with short pubescence. Sternites 1, 2 completely fused, forming small triangular plate, separated from sternite 3 by distinct suture; sternite 3, 4 completely fused except for lateral clefts; sternite 3 discernible as small triangular plate, medially depressed; sternite 4 strongly constricted, anterior part much narrower than posterior part, with anterolateral margins almost parallel, median part of lateral margins strongly convex (Figs. 2 A).
Abdomen broadly triangular, with 6 free somites, telson; somites 3, 4 trapezoidal; somites 5, 6 subrectangular, somite 6 longer; telson broadly triangular, subequal in length to somite 6, with almost straight lateral margins (Figs. 2 A).
G1 relatively straight, flattened laterally along distal third; distal part forming 3 folds (Fig. 4 A?C). G2 short, about a quarter length of G1; tip with cup-like structure, no distal segment (Fig. 4 D).
Female abdomen rounded, dome-shaped, covering entire thoracic sternum; all somites, telson free; outer surface of somites with raised median ridge of tubercles. Sterno-abdominal cavity deep; vulva large, raised, opening large, subcircular (Fig. 3E).
Etymology. The new species is named for the long hepatic and lateral branchial spines.
Remarks. The two female specimens from New Caledonia agree well with the holotype male in most nonsexual characters. The smaller female (12.9 × 8.9 mm, MNHN-IU-2013-1678) (Fig. 3A) is already fully mature, with the abdomen forming a dome-like structure covering the entire thoracic sternum and is ovigerous. The larger female (13.8 × 96.1 mm, ZRC ex MNHN-IU-2013-1688) is not fully mature with the abdomen not swollen and covering only about half the thoracic sternum. In both females, the hepatic spines are directed more laterally than in the male (Fig. 1 A) but are shorter than the lateral branchial carapace spines (Fig. 3A).
Other than the generic differences between Rochinia and Samadinia n. gen. (see remarks for Rochinia), Samadinia longispina n. gen., n. sp. superficially resembles species like Rochinia strangeri Serène & Lohavanijaya, 1973, and R. kotakae Takeda, 2001, in having long pseudorostral spines and a long lateral branchial spine. These two species, however, have weaker hepatic spines, smooth carapaces and the regions have distinct tubercles. The new species also resembles R. paulayi Ng & Richer de Forges, 2007, in having long, subequal hepatic and lateral branchial spines; but all the carapace regions of R. paulayi also have long spines, absent in S. longispina n. gen., n. sp.
description: Published as part of Ng, Peter K. L. & Forges, Bertrand Richer De, 2013, Samadinia longispina, a new genus and species of deep-sea spider crab from the western Pacific, and a new species of Rochinia A. Milne-Edwards, 1875, from Papua New Guinea (Crustacea: Brachyura: Majoidea: Epialtidae), pp. 357-366 in Zootaxa 3718 (4) on pages 358-361, DOI: 10.11646/zootaxa.3718.4.5, http://zenodo.org/record/221762