Rochinia granulosa, Ng, Peter K. L. & Forges, Bertrand Richer De, 2013

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), Zootaxa 3718 (4), pp. 357-366 : 363-365

Rochinia granulosa n. sp.

( Figs. 3B ?D, F, 4E, F)

Material examined. Holotype: female (9.7 × 6.7 mm) (MNHN-IU- 2011-2944 a), stn DW 3754, Papua New Guinea, near Bougainville Island, 615– 532 m, coll. BIOPAPUA, RV Alis, 13 October 2010. Paratypes: 1 male (6.4 × 4.7 mm) (MNHN-IU- 2011-2944 b), 1 female (9.9 × 7.0 mm) (ZRC), same data as holotype.

Diagnosis. Dorsal surface of carapace with relatively large, rounded granules, forming groups on gastric, cardiac areas ( Fig. 3B, C ). Pseudorostral spines long, straight, diverging ( Fig. 3B, C ). Ocular peduncules short with rounded cornea ( Fig. 3B, C ). Supraocular eave narrow forming a triangular tooth, directed anteriorly; postocular tooth broadly triangular ( Fig. 3B, C ). Hepatic spine triangular, short, with rounded or relatively blunt tip ( Fig. 3B, C ). Lateral margin with relatively large granules, with prominent lateral spine directed sublaterally ( Fig. 3B, C ). Basal antennal article broad, with distal blunt tooth ( Fig. 3D ). Ambulatory legs, especially meri, relatively short ( Fig. 3B, C ). Anterior male thoracic sternum relatively broad transversely ( Fig. 3D ). Male abdomen triangular ( Fig. 3D ). Female abdomen rounded; surface smooth.

Description. Carapace pyriform; dorsal surface with regions weakly defined, covered by relatively large rounded granules, forming groups on gastric, cardiac areas, without large tubercles or spines; cardiac region convex ( Figs. 3B, C ). Pseudorostral spines long, slender, straight, subcylindrical in cross-section, prominently diverging outwards ( Figs. 3B, C ). Supraocular eave relatively narrow, forming distinct anteriorly directed acutely triangular tooth; postocular tooth relatively short, broadly triangular, outer margin convex or almost straight ( Fig. 3B, C ). Hepatic spine triangular, short, with rounded or blunt tip; directed obliquely outwards ( Fig. 3B, C ). Lateral carapace margin with relatively large granules, lateral branchial spine well developed, directed sublaterally ( Fig. 3B, C ). Intestinal region with 2 rounded tubercles (may be low) just before posterior carapace margin ( Fig. 3B, C ).

Ocular peduncle short; cornea round, pigmented ( Fig. 3B, C ). Suborbital margin confluent with lateral margin of basal antennal article. Basal antennal article broad, with distal blunt tooth; flagellum relatively short, slender, positioned outside orbit ( Fig. 3D ). Antennules folding almost vertically ( Fig. 3D ). Epistome longitudinally narrow; posterior margin crenulated ( Fig. 3D ). Pterygostomial area almost smooth, separated from sub-branchial region by row of 3 or 4 low tubercles ( Fig. 3D ). Third maxillipeds completely covering buccal cavity when closed; surfaces smooth, covered by short pubescence; ischium with distinct median sulcus; merus quadrate, anterolateral margin auriculiform; exopod relatively stout, reaching to middle of merus, with long flagellum ( Fig. 3D ).

Chelipeds subequal, chelae not inflated; merus trigonal in cross-section, with low distal tooth on dorsal margin; carpus short; surface of palm almost smooth; fingers slightly shorter than palm, cutting margins gently serrulated, more prominent along distal half ( Fig. 3B ?D). Ambulatory legs relatively short; first leg longest, fourth leg shortest; surfaces with scattered short setae; meri short, unarmed; carpus short with lateral sulcus; dactylus tapering, surface with short setae except for corneous tip ( Fig. 3B, C ).

Anterior male thoracic sternum relatively broad transversely ( Fig. 3D ); surface almost glabrous. 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 medially almost flat, lateral margins concave ( Figs. 3D ).

Abdomen triangular, with 6 free somites, telson; somites 3, 4 trapezoidal; somites 5, 6 subrectangular, somite 6 slightly longer; telson broadly triangular, longer than somite 6, with gently concave lateral margins ( Figs. 3D ).

Adult G1 not known, juvenile G1 relatively straight, flattened laterally along distal quarter; distal part subtruncate ( Fig. 4 E, F). G2 very short.

Female abdomen rounded, dome-shaped, covering entire thoracic sternum; all somites and telson free; outer surfaces smooth. Sterno-abdominal cavity deep; vulva large, not raised, flushed with rest of sternal surface, opening large, subcircular ( Fig. 3 F).

Etymology. The species is named after the large granules covering the carapace.

Remarks. Superficially, Rochinia granulosa n. sp. is closest to Samadinia longispina n. sp. in the general shape, and in the presence of many granules on the dorsal surface of the carapace, which has weakly defined regions. It differs, however, by the following characters: the adult size is relatively small, with females 6.7 mm in carapace width already mature (the single adult female of S. longispina n. sp. is 12.9 × 8.9 mm, MNHN-IU-2013- 1678); the male thoracic sternum is proportionally broader ( Fig. 3D ) (cf. S. longispina n. sp., Fig. 2 A); the carapace and margin are covered by a relatively smaller number of proportionally larger granules ( Fig. 3B, C ) (large number of small rounded granules in S. longispina n. sp., Figs. 1 A, 3A); the pseudorostral spines are relatively shorter, straight and less divergent ( Fig. 3B, C ) than in S. longispina n. sp. ( Figs. 1 A, 3A); the spines on the hepatic and lateral branchial regions are relatively short and blunt ( Fig. 3B, C ) (long and sharp in S. longispina n. sp.: Figs. 1 A, 3A); the ambulatory legs (notably the meri) are relatively shorter ( Fig. 3B, C ) (cf. longer in S. longispina n. sp., Figs. 1 A, 3A); the male abdomen is markedly less broad ( Fig. 3D ) (cf. broader in S. longispina n. sp., Fig. 2 A); and the abdomen of the ovigerous female is rounded and smooth (with a raised median ridge of tubercles in S. longispina n. sp.).

The only male is a pre-adult specimen with the G1 ( Fig. 4 E, F) not yet fully chitinised.

Figures

FIGURE 1. Samadinia longispina n. gen., n. sp., holotype male (25.3 × 17.9 mm) (MNHN-IU- 2011 - 4190), French Polynesia, south of Society Islands. A, overall habitus; B, lateral view of carapace (lateral branchial spine broken); C, lateral-frontal view showing orbit and position of antennal flagellum.

FIGURE 2. Samadinia longispina n. gen., n. sp., holotype male (25.3 × 17.9 mm) (MNHN-IU- 2011 - 4190), French Polynesia. A, anterior thoracic sternum and abdomen; B, antennules, antennae and epistome; C, left third maxilliped; D, left chela.

FIGURE 4. Gonopods. A-D, Samadinia longispina n. gen., n. sp., holotype male (25.3 × 17.9 mm) (MNHN-IU- 2011 - 4190), French Polynesia, south of Society Islands; E, F, Rochinia granulosa n. sp., paratype male (6.4 × 4.7 mm) (MNHN-IU- 2011 - 2944 b), Papua New Guinea, Madang. A, E, left G 1 (ventral views); B, F, distal part of left G 1 (ventral views); C, distal part of left G 1 (dorsal view); D, left G 2. Scales: A, D = 1.0 mm, E = 0.25 mm, B, C = 0.5 mm, F = 0.1 mm.

FIGURE 3. A, E, Samadinia longispina n. gen., n. sp., female (12.9 × 8.9 mm) (MNHN-IU- 2013 - 1678), New Caledonia; B- D, Rochinia granulosa n. sp., B, F, holotype female (9.7 × 6.7 mm) (MNHN-IU- 2011 - 2944 a), Papua New Guinea; C, D, paratype male (6.4 × 4.7 mm) (MNHN-IU- 2011 - 2944 b), Papua New Guinea. A-C, overall habitus; D, male anterior thoracic sternum and abdomen; E, F, female sterno-abdominal cavities and vulvae.