Geosesarma robustum, Ng & Wowor, 2019

Ng, Peter K. L. & Wowor, Daisy, 2019, The vampire crabs of Java, with descriptions of five new species from Mount Halimun Salak National Park, West Java, Indonesia (Crustacea: Brachyura: Sesarmidae: Geosesarma), Raffles Bulletin of Zoology 67, pp. 217-246 : 228-230

Geosesarma robustum , new species

( Figs. 11 , 12 )

Material examined. West Java Province, Bogor Regency: holotype: male (9.6 × 9.2 mm) ( MZB Cru 4452), Tenjolaya District , Ds. Tapos 1, Kp. Sinar Wangi, near dam at headwaters of S. Ciampea, in middle of primary forest, 06°41′36.0″S 106°42′23.7″E, 1,032 m asl, coll. D. Wowor et al., 2 October 2015 .

Diagnosis of male. Carapace quadrate, slightly wider than long, lateral margins almost straight, slightly divergent ( Fig. 11A, B ); dorsal surface with clear regions, anterior regions with numerous small granules ( Fig. 11B, C ); front deflexed, frontal lobes broad with gently convex margins, separated by shallow median concavity; postfrontal cristae sharp ( Fig. 11B, C ); external orbital tooth triangular, directed obliquely outwards, tip extending just beyond anterior part of lateral carapace margin, first epibranchial tooth truncate, barely separated from margin by small cleft ( Fig. 11B ). Ischium of third maxilliped ovate; exopod relatively slender, with long flagellum that extends just beyond merus width ( Fig. 12A ). Outer surface of palm of adult male chelae with low granules; inner surface granulated but without transverse comb-like ridge; dorsal margin of dactylus with 3 distinct large tubercles on proximal third, each with chitinous tip ( Fig. 11 F–H). Ambulatory legs with relatively broad meri, with sharp subdistal spine on dorsal margin, surfaces rugose; ventral margins of propodus and dactylus of adult first ambulatory leg with dense comb-like setae. Male pleon triangular; telson triangular with rounded tip, as long as broad; somite 6 trapezoidal, with gently convex to almost straight lateral margins ( Fig. 11D, E ). G1 very stout, short, subdistal part of outer margin before chitinous distal part gently angular with inner dorsal section strongly developed; chitinous distal part bent about 45° along longitudinal axis, short, truncate in lateral view, spatuliform in mesial view; tip truncate when viewed dorsally ( Fig. 12 B–F).

Females. Not known.

Etymology. The name alludes to the stout structure of the G1.

Remarks. See General Discussion for comparisons with allied Javan species.

Notes on habitat. It was found at the side of head water stream, under cobbles of 10 to 20 m diameter with a bit of water ( Fig. 25D ). It is in an open area far from human settlement, surrounded by forest. It is a highland species that lives above 1,000 m asl.

Life colouration. The carapace is purplish dark brown with black eyes and dark brown chelae.

Distribution. Bogor Regency in Jawa Barat Province, in Gunung Bunder Resort of Mount Halimun Salak National Park.

Figures

Fig. 11. Geosesarma robustum, new species, holotype male (9.6 × 9.2 mm) (MZB Cru 4452). A, overall dorsal view; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum, telson and pleonal somites 5 and 6; E, anterior thoracic sternum, telson and pleonal somites 3–6; F, outer view of right chela; G, dorsal view of right chela; H, dorsal view of dactylus of right chela.

Fig. 12. Geosesarma robustum, new species, holotype male (9.6 × 9.2 mm) (MZB Cru 4452). A, left third maxilliped; B, left G1 (dorsal view); C, left G1 (ventral view); D, E, left G1 (ventro-mesial view); F, left G1(dorso-mesial view); G, left G2. All structures denuded. Scales: A = 1.0 mm; B–G = 0.5 mm.

Fig. 25. Habitats. A, Geosesarma noduliferum habitat, stream at Tenjolaya District, Bogor Regency; B, G. lebak, new species, edge of S. Cimaja in Banten Province; C, G. sukabumi, new species, cliff face above S. Cirendang, Sukabumi Regency; D, G. robustum, new species, head water of S. Ciampea, Bogor Regency; E, G. cikaniki, new species, moist forest in Cikaniki Research Station, Bogor Regency.