Sundathelphusa vienae, Husana, Daniel Edison M., Yamamuro, Masumi & Ng, Peter K. L., 2014

Husana, Daniel Edison M., Yamamuro, Masumi & Ng, Peter K. L., 2014, Two new species of freshwater crabs of the genus Sundathelphusa Bott, 1969 (Decapoda: Brachyura: Gecarcinucidae) from caves in Luzon, Philippines, Zootaxa 3815 (4), pp. 565-574 : 569-572

Sundathelphusa vienae sp. nov.

( Figs. 4–6 , 7 C, D)

Material examined. Holotype: male (21.3 × 17.9 mm) ( NMCR 39077), Nilulubugan Cave, Atimonan, Quezon Province, Luzon, Philippines, 14˚ 01.000N, 121˚ 47.775E, coll. D.E.M. Husana, December 2009. Paratype: 1 female (19.8 × 16.5 mm) (NSMT-Cr 22317).

Description. Carapace distinctively quadrate ( Fig. 4 A), widest at anterior quarter, broader than long, dorsal surface convex longitudinally, dorso-ventrally inflated, regions distinct; branchial regions covered with distinct oblique striae; cervical groove prominent; H-shaped gastric groove distinct. Epigastric cristae distinct, edges sharp, separated by distinct median furrow; postorbital cristae, sharp; epigastric, postorbital cristae, not confluent; epibranchial teeth, postorbital cristae not confluent. Frontal margin ( Figs. 4 B, 5C) protruded, gently sinuous, deflexed. External orbital tooth triangular, produced anteriorly; outer margin convex, longer than inner margin; epibranchial tooth distinct, small, well separated from external orbital tooth by notch; anterolateral margin convex, armed with small granules, clearly demarcated from posterolateral margin; posterolateral margin almost straight to gently concave, with oblique striae converging gradually towards posterior margin of carapace. Frontal median triangle ( Figs. 4 B, 5C) distinct but not complete, with protruded dorsal margin; orbit well demarcated; supraorbital margin smooth; infraorbital margin beaded with distinct granules; outer edge reaching, fused with anterolateral margin; suborbital, subbranchial regions covered with few scattered oblique striae of various sizes; pterygostomial region with streak of oblique ridges on upper part. Posterior margin of epistome ( Figs. 4 B, 5D) with 3 lobes, median lobe, triangular; lateral lobes wider, distal margin more protruded anteriorly.

Eyes well developed ( Fig. 4 B), occupying almost entire orbit. Third maxilliped ischium ( Fig. 6 A) rectangular, much longer than broad, bearing distinct oblique submedian sulcus closer to mesial margin; merus quadrate, distalexternal angle convex, upswept; tip of exopod not reaching midpoint of outer margin of merus, with flagellum reaching beyond edge of mesial margin of merus.

Chelipeds not noticeably elongated, subequal, stronger in males; margins of merus serrated, dorsal margin with small subdistal tooth; carpus armed with strong distal sharply pointed inner tooth, dorso-ventrally flattened; palm with smooth outer surface; fingers robust, cutting edges armed with medium-sized to large sharp teeth.

Ambulatory legs ( Figs. 4 A, 5B) long, slender, second leg longest, anterior margins of meri distinctly serrated, without subdistal tooth or spine, posterior margins smooth on all legs; second, third pair shorter than carapace length; carpi short, with longitudinal submedian ridge on dorsal surface, widened distally; propodi, dactyli subequal in length.

Male abdominal cavity reaching level of proximal quarter of coxae of chelipeds. Male abdomen ( Figs. 5 A, 6B) narrow, T-shaped; somite 1 short, somite 6 longer than broad; proximal, distal margins of somites 3–5 sinuous; lateral margins of somite 2 convex; lateral margins of somite 3 convex; lateral margins of somite 4 straight, narrows gradually to distal end; somites 3–5 narrow gradually; lateral margins of somite 5 concave, proximally wide distally narrow; lateral margins of somite 6 straight; telson subtriangular, broader than long, lateral margin slightly concave medially, rounded distally. G1 ( Figs. 5 E, F, H, I) slender, slightly bent outwards; subterminal segment gradually tapering towards terminal segment, segments separated by distinct suture; terminal segment straight, tapering, cylindrical. G2 ( Figs. 5 G, J) subequal in length to G1, flagellum short.

Female. Female chelipeds subequal, neither inflated; abdomen ovate, covering entire thoracic sternum, all somites and telson freely articulating; telson broadly triangular with convex lateral margins ( Fig. 7 C). Vulvae large, subovate, without operculum; on median part of somite 6 ( Fig. 7 D).

Coloration. Dorsal surface of carapace is brownish to orange in life, chelipeds are yellowish to orange.

Etymology. Named after a daughter of the first author, Vien Danille Husana, who accompanied him in some of his fieldwork.

Remarks. Sundathelphusa vienae sp. nov. is unusual among Sundathelphusa species in that it has a relatively high carapace like S. picta (von Martens, 1868) and its allies. The new species, however, has a more quadrate carapace and proportionately longer ambulatory legs in contrast to the more ovate inflated carapace and shorter legs of the latter (cf. Bott 1970: pl. 12 figs. 36–38). The G1 is also more slender than in S. picta and almost straight, with its tapering pointed terminal segment ( Figs. 5 E, F, H, I; versus Bott 1970: pl. 28 fig. 50).

Figures

FIGURE 4. Sundathelphusa vienae sp. nov., holotype male (21.3 × 17.9 mm) (NMCR 39077), Nilulubugan Cave, Atimonan, Quezon Province, Luzon, Philippines: A, habitus, dorsal view; B, cephalothorax, anterior view. Scale bars, A, B = 5.0 mm.

FIGURE 5. Sundathelphusa vienae sp. nov., holotype male (21.3 × 17.9 mm) (NMCR 39077), Nilulubugan Cave, Atimonan, Quezon Province, Luzon, Philippines. A, male abdomen [telson and somite 6 damaged]; B, left second ambulatory leg, ventral view; C, frontal margins, frontal view; D, posterior margin of epistome; E, left G 1, ventral view; F, left G 1, dorsal view; G, left G 2; H, terminal segment of left G 1, ventral view; I, terminal segment of left G 1, dorsal view; J, flagellum of left G 2. Scale bars, A, B = 2.0 mm; C, D = 2.0 mm; E ‒ G = 1.0 mm; H ‒ J = 0.5 mm.

FIGURE 6. Sundathelphusa vienae sp. nov., holotype male (21.3 × 17.9 mm) (NMCR 39077), Nilulubugan Cave, Atimonan, Quezon Province, Luzon, Philippines: A, buccal field and thoracic sternum; B, abdomen. Scale bars, A, B = 5.0 mm.

FIGURE 7. A, B, Sundathelphusa danae sp. nov., female (20.4 × 16.8 mm) (NMCR 39093), Bantakay Cave, Atimonan, Quezon Province, Luzon, Philippines; C, D, Sundathelphusa vienae sp. nov., paratype female (19.8 × 16.5 mm) (NSMT-Cr 22317), Nilulubugan Cave, Atimonan, Quezon Province, Luzon, Philippines. A, C, female abdomens; B, D, thoracic sternums showing vulvae.