Two new species of land-dwelling crabs of the genus Geosesarma De Man, 1892 (Crustacea: Brachyura: Thoracotremata: Sesarmidae) from Bintan Island, Indonesia Author Schubart, Christoph D. Author Ng, Peter K. L. text Raffles Bulletin of Zoology 2014 2014-08-22 62 615 619 journal article 10.5281/zenodo.4504166 2345-7600 4504166 924CD2C9-3007-4321-81E2-0237EE1359BA Geosesarma raj , new species ( Figs. 1B, D , 2B, D , 3B, D, F , J–M, 4) Material examined. Holotype – male (11.8 × 10.9 mm ) ( MZB Cru 3814, ex ZRC 2007.0676 ), Indonesia : Riau Archipelago, northern Bintan Island , coll. G. Subaraj , 18 October 2007 . Paratypes – 1 female (11.8 × 10.7 mm ) ( ZRC 2007.0677 ), Indonesia : Riau Archipelago , Bintan Island , in tree hole, coll. G. Subaraj , 21 October 2007 ; 1 male (10.0 × 9.7 mm ) ( ZRC 2007.0675 ), Indonesia : Riau Archipelago , Bintan Island : Gunong (= Mount ) Bintan , above lower waterfalls (attacked by ants), coll. G. Subaraj , 23 June 2007 ; 1 male (9.4 × 9.0 mm), 2 females (7.3 × 6.8 mm , 6.4 × 6.2 mm ) ( ZRC 1996.133 – 135 ), Gunung Bintan Besar , coll. Y. H. Lee , 19 February 1996 . Fig. 1. A, C, Geosesarma bintan , new species , holotype, male, 11.2 × 9.8 mm (MZB Cru 3813), Bintan Island; B, D, Geosesarma raj , new species , holotype, male, 11.8 × 10.9 mm (MZB Cru 3814, ex ZRC 2007.0676), Bintan Island. A, B, habitus; C, D, dorsal view of carapace. Fig. 2. A, C, Geosesarma bintan , new species , holotype, male, 11.2 × 9.8 mm (MZB Cru 3813), Bintan Island; B, D, Geosesarma raj , new species , holotype, male, 11.8 × 10.9 mm (MZB Cru 3814, ex ZRC 2007.0676), Bintan Island. A, B, frontal view of carapace; C, D, outer view of right chela. Fig. 3. A, C, E, G–I, Geosesarma bintan , new species , holotype, male, 11.2 × 9.8 mm (MZB Cru 3813), Bintan Island; B, D, F, J–M, Geosesarma raj , new species , holotype, male, 11.8 × 10.9 mm (MZB Cru 3814, ex ZRC 2007.0676), Bintan Island. A, B, outer view of left third maxilliped; C, D, left fourth ambulatory leg, dorsal view; E, F, male abdomen; G, ventral view of left G1 (denuded); H, lateral view of left G1 (denuded); I, dorsal view of left G1 (denuded); J, ventral view of left G1 (denuded); K, dorsal view of left G1 (denuded); L, M, distal part of left G1 (denuded). Scale bars: A, B, E–I = 1.0 mm; C, D = 2.0 mm; J, K = 0.5 mm; L, M = 0.25 mm. Diagnosis. Carapace almost squarish, not distinctly wider than long, lateral margins almost parallel ( Fig. 1B, D ); dorsal surfaces evenly covered with numerous granules and striae; H-shaped median depression deep; postfrontal cristae prominent, margins sharp; exorbital tooth triangular, curving obliquely, with additional low tooth behind it ( Figs. 1B , 2B ). Exopod of third maxilliped relatively stout, without flagellum ( Fig. 3B ). Male chelae with long fingers, numerous granules on palm (dorsally and ventrally) and proximal part of dactylus; dorsal margin of dactylus with 8 or 9 sharp granules on proximal two-thirds ( Fig. 2D ). Ambulatory legs with relatively slender meri, with sharp subdistal spine on dorsal margin, surface almost smooth; propodus elongate ( Figs. 1B , 3D ). Male abdomen relatively narrow; telson longer than broad, with rounded tip ( Fig. 3F ). G1 relatively stout, distal chitinous part elongate, tapering; subdistal part broad ( Fig. 3 J–M). Colour. The carapace of this species is reddish brown in life, with the chelipeds bright orange ( Fig. 4 ). Etymology. The species is named after G. Subaraj (“Raj” to all his friends), the collector. The specific epithet, raj , is used as a noun in apposition. Remarks. The quadrate carapace, the absence of a flagellum on the exopod of the third maxilliped, and the stout G1, which has a prominent, chitinised, beak-like structure on the distal end with the subdistal part broad, ally Geosesarma raj , new species , with species like G. malayanum Ng & Lim, 1986 , G. scandens Ng, 1986 , G. tiomanicum Ng, 1986 , from Peninsular Malaysia , and G. katibas Ng, 1995 , from Sarawak , East Malaysia . Geosesarma raj , new species , can be distinguished from G. scandens ( type locality: Fraser’s Hill) by its relatively longer third maxilliped merus ( Fig. 3B ) (shorter in G. scandens ; cf. Ng, 1988 : fig. 62C) and the upward-directed (at a more gradual angle) chitinised distal part of the G1 ( Fig. 3 J–M) (chitinised distal part directed at a steeper angle in G. scandens ; cf. Ng, 1988 : fig. 62D, E). Geosesarma raj , new species , can be separated from G. malayanum ( type locality: Johor ) by its more rugose dorsal surfaces of the carapace ( Fig. 1B, D ) (relatively less rugose in G. malayanum ; cf. Ng & Lim, 1987 : pl. 1; Ng, 1988 : fig. 63A); relatively shorter ambulatory legs ( Fig. 1B ) (longer in G. malayanum ; cf. Ng & Lim, 1987 : pl. 1; Ng, 1988 : fig. 63A); and the G1 which is slightly less stout, with the chitinised distal part relatively longer ( Fig. 3 J–M) (stouter with the chitinised distal part relatively short in G. malayanum ; cf. Ng & Lim, 1987 : fig. 1; Ng, 1988 : fig. 63D–G). The new species differs from G. tiomanicum ( type locality: Pulau Tioman) by its relatively longer third maxilliped merus ( Fig. 3B ) (relatively shorter merus in G. tiomanicum ; cf. Ng, 1988 : fig. 61C), the tip of the chitinised distal part of the G1 being subtruncate ( Fig. 3 J–M) (tip sharp; cf. Ng, 1988 : fig. 61D, E). From G. katibas ( type locality: Sarawak ), G. raj , new species , can be distinguished by its relatively longer third maxilliped merus ( Fig. 3B ) (shorter in G. katibas ; cf. Ng, 1995: fig. 11B); the dorsal margin of the dactylus of the male major chela having fewer (8 or 9) and less developed granules ( Fig. 2B ) (11 distinct granules; cf. Ng, 1995: fig. 11C, D); and the G1 being proportionately longer and less stout ( Fig. 3 J–M) (relatively shorter and stouter in G. katibas ; cf. Ng, 1995: fig. 12A–E). In many other parts of Peninsular Malaysia and Singapore , there is one lowland species living in swampy areas, often in burrows, and another that occurs in higher altitudes, under rocks in fast-flowing streams. In Johor and Singapore , for example, G. peraccae occurs in lowland freshwater swamps while G. nemesis and G. malayanum prefer high-elevation areas with fast-flowing streams (see Ng & Lim, 1987 ; Ng, 1988 , 1990 ). The same situation appears to be present in Pulau Bintan, with G. bintan as the lowland species while G. raj occurs in more montane habitats, but not necessarily in streams.