Geosesarma lebak, 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 : 222-225

Geosesarma lebak , new species

( Figs. 5 , 6 A–C, 7)

Material examined. Banten Province, Lebak Regency: holotype: male (11.7 × 11.3 mm) ( MZB Cru 4563), Sobang District , Ds. Majasari , S. Cimaok , ca. 06°38′35.5″S 106°22′22.0″E, 685 m asl, coll. Ibu Warung, 28 May 2016 . Paratypes: 10 males (9.9 × 9.0 mm – 11.7 × 11.1 mm), 1 female (9.7 × 9.4 mm) 1 female (damaged, 10.9 mm carapace width) ( MZB Cru 4648), 2 males (11.0 × 10.7 mm, 11.2 × 10.8 mm) ( ZRC 2018.0285 ex-MZB Cru 4648), data same as holotype ; 7 males (7.6 × 7.0 mm – 11.3 × 10.5 mm), 6 females (8.6 × 7.6 mm – 12.9 × 11.5 mm), 2 juveniles ( MZB Cru 4553), Sobang District, Ds. Majasari , Kp. Maja , S. Cimaja , 06°39′15.7″S 106°21′43.7″E, 536 m asl, coll. D. Wowor et al., 26 May 2016 ; 6 males (8.2 × 7.4 mm – 11.7 × 11.1 mm), 5 females (7.9 × 7.0 mm – 11.2 × 10.3 mm) ( MZB Cru 4551), 1 male (10.8 × 9.6 mm), 2 females (11.8 × 10.4 mm, 12.2 × 10.6 mm) ( ZRC 2018.0286 ex-MZB Cru 4551), Sobang District, Ds. Majasari, Kp. Majaharja, S. Cigehong, a small tributary at the back of Jaro M. Yunus (head of village) home, 06°39′07.4″S 106°22′05.5″E, 588 m asl, coll. D. Wowor et al., 28 May 2016 .

Diagnosis of male. Carapace squarish, wider than long, lateral margins gently concave, subparallel ( Fig. 5A, B ); dorsal surface with distinct regions, anterior regions with numerous small rounded granules ( Fig. 5B, C ); front deflexed, frontal lobes very broad with almost truncate margins, separated by broad median concavity; postfrontal cristae sharp ( Fig. 5B, C ); external orbital tooth triangular, directed obliquely outwards, tip slightly extending beyond anterior part of lateral carapace margin, first epibranchial tooth triangular, well defined, separated from margin by distinct cleft ( Fig. 5B ). Ischium of third maxilliped ovate, wide; exopod relatively slender, with long flagellum that extends beyond merus width ( Fig. 7A ). Outer surface of palm of adult male chelae granulate; inner surface granulated but without distinct transverse comb- like ridge; dorsal margin of dactylus with 10 or 11 evenly spaced small tubercles (last one near tip may be very small), each with chitinous tip ( Fig. 5 F–H). Ambulatory legs with relatively broad meri, with sharp subdistal spine on dorsal margin, surfaces gently rugose; ventral margins of propodus and dactylus of adult first ambulatory leg with scattered stiff setae ( Fig. 5A ). Male pleon triangular; telson triangular with rounded tip, longer than broad; somite 6 with convex lateral margins ( Fig. 5D, E ). G1 relatively slender, subdistal part of outer margin before chitinous distal part angular with inner dorsal section strongly developed; chitinous distal part bent about 45º along longitudinal axis, elongate, tapering, slender in lateral view, subspatuliform in mesial view; tip clefted when viewed dorsally ( Figs. 6G, H , 7 B–E).

Females. The adult female carapace is slightly broader and more trapezoidal in form ( Fig. 6A ). The vulvae are on the anterior half of sternite 6, raised, directed obliquely inwards towards the median line of the sternum, the margin is indented medially and without a sternal opercular cover ( Fig. 6C ).

Etymology. The species is named after the locality where the holotype of the new species was found. The name is used as a noun in apposition.

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

Notes on habitat. This species inhabits side of slow-moderate current streams, under the cobbles nearby human settlement and rice field. It can be also found under the cobbles of dried tributaries but with the substrate still moist ( Fig. 25B ). The habitat is open area with little canopy coverage. Geosesarma lebak , new species, lives between 500 to 700 m asl.

Life colouration. It has reddish dark brown carapace, yellow eyes and bright red chelae ( Fig. 26A ).

Distribution. Lebak Regency in Banten Province, in Gunung Bongkok Resort of Mount Halimun Salak National Park.

Figures

Fig. 5. Geosesarma lebak, new species, holotype male (11.7 × 11.3 mm) (MZB Cru 4563). A, overall dorsal view; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum, telson and pleonal somites 4–6; E, 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. 6. A–C, Geosesarma lebak, new species, paratype female (12.2 × 10.6 mm) (ZRC 2018.0286); D, G. noduliferum (De Man, 1892), male (11.3 × 10.6 mm) (MZB Cru 4796); E, F, G. noduliferum (De Man, 1892), male (10.9 × 10.2 mm) (MZB Cru 4796); G, H, G. lebak, new species, paratype male (11.2 × 10.8 mm) (ZRC 2018.0285). A, overall dorsal view; B, anterior thoracic sternum, telson and pleonal somites 4–6; C, sternopleonal cavity showing vulvae; D, E, G, left G1 (dorsal view); F, H, distal part of left G1 (dorsal view).

Fig. 7. Geosesarma lebak, new species, holotype male (11.7 × 11.3 mm) (MZB Cru 4563). A, left third maxilliped; B, left G1 (dorsal view); C, left G1 (ventral view); D, left G1 (ventro-mesial view); E, left G1 (dorso-mesial view); F, left G2. All structures denuded. Scales: A = 1.0 mm; B–F = 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.

Fig. 26. Colour in life. A, Geosesarma lebak, new species, male (11.3 × 10.5 mm) (MZB Cru 4553), S. Cimaja, Banten Province; B, G. sekop, new species, holotype male (10.5 × 9.4 mm) (MZB Cru 4455), Curug Muara Herang, Bogor Regency. A, photograph by R.M. Marwoto; B, photograph by R.K. Hadiaty.