Geosesarma hagen, Ng & Schubart & Lukhaup, 2015

Ng, Peter K. L., Schubart, Christoph D. & Lukhaup, Christian, 2015, New species of “ vampire crabs ” (Geosesarma De Man, 1892) from central Java, Indonesia, and the identity of Sesarma (Geosesarma) nodulifera De Man, 1892 (Crustacea, Brachyura, Thoracotremata, Sesarmidae), Raffles Bulletin of Zoology 63, pp. 3-13 : 11

Geosesarma hagen , new species

( Figs. 3C, D , 4 H–M, 5E, G, 6D–F, 7E, F)

Material examined. Holotype: male (13.9 × 13.3 mm) ( MZB 4062 ), station R605–1, north of Cilacap town , Cilacap Regency, central Java, 7°27’50”S, 108°50’16”E, Indonesia, coll. C. Lukhaup, 5 October 2011 . Paratypes: 1 male (13.2 × 12.2 mm), 1 female (14.5 × 13.4 mm) ( ZRC 2014.0269 ), same data as holotype ; 2 males (larger 12.5 × 12.2 mm), 2 females (larger 11.6 × 10.9 mm) ( SMF 46287) , 2 males (larger 12.2 × 11.6 mm), 1 female (11.3 × 10.7 mm) ( ZRC 2014.0268 ), same data as holotype. Others : 1 male (12.9 × 11.8 mm) ( ZRC 2014.0272 ), from aquarium dealer in Cilacap town , Java, 12 April 2011 ; 2 males (larger 12.6 × 11.6 mm) ( ZRC 2014.0267 ), from aquarium trade, ostensibly from Cilacap, Java, from O. Mengedoht, 9 June 2010 .

Description. Carapace squarish, slightly wider than long, lateral margins subparallel ( Fig. 3C, D ); dorsal surface with well-defined regions, anterior regions very densely covered with small rounded granules ( Fig. 3C, D ); front deflexed, frontal lobes broad with convex margins; postfrontal cristae prominent ( Fig. 3C, D ); external orbital tooth large, triangular, curving obliquely outwards, tip protruding beyond level of lateral carapace margin ( Fig. 3D ). Exopod of third maxilliped relatively slender, with long flagellum extending beyond merus width ( Fig. 4H ). Outer surface of palm of adult male chelae granulated; dorsal margin of dactylus with 7–9 tubercles (distal one may be very low), each with pectinated tip ( Fig. 5E ). Ambulatory legs with relatively broad meri, with sharp subdistal spine on dorsal margin, surfaces rugose ( Figs. 3C , 5G ). Male abdomen relatively broad; telson semicircular; somite 6 with strongly convex lateral margins ( Fig. 4I ). G1 slender, proximal part straight, distal part pectinated, bent, elongate, spatuliform; tip entire, subtruncate when viewed dorsally ( Fig. 4 J–M).

Colour. Adult coloration in life: dark brown on anterior half or third of carapace and ambulatory legs; posterior half or two thirds of carapace orange or yellow; thoracic sternum greyish-white to grey with numerous grey specks; abdomen dark grey with small white spots; chelae bright orange; eyes bright yellow ( Figs. 6 D–F, 7E, F). The extent of bright orange on the dorsal surface of the carapace varies considerably, with some specimens being almost completely orange ( Fig. 6D, E ). The chelae in adults are bright or reddish-orange ( Figs. 6E , 7E, F ), but those from smaller specimens are generally more reddish ( Fig. 6F ).

Etymology. Geosesarma hagen is named after the Rolf C. Hagen Group of Companies, a major pet supplies company in Germany. They kindly supported the third author’s projects in Java and subsequent work by the second author. The name is used as a noun in apposition.

Ecology. The crabs were found on a banana and rubber plantation on the side of a small hill, around 300 m from the road ( Fig 7D ). There are many trickles of water and a somewhat larger rivulet in the small area where they occur. Adult crabs are terrestrial, hiding under the dense bottom vegetation, usually under and between rocks, but they also sometimes excavate burrows at the edge of the water bodies ( Fig. 7E ). They seem to be carnivorous, feeding at least partially on insects inhabiting the ground. While adult crabs are seldom found in the water and mostly live on the moist banks ( Fig. 7F ), juveniles are often in the water or very close to the waterline, and are much less frequently seen on the drier forest ground.

Remarks. Material obtained from the aquarium trade by Rademacher & Mengedoht (2011) identified as “ Geosesarma “Rot” Vampirkrabbe” (p. 44) are Geosesarma hagen , new species, on the basis of their colour photographs and specimens examined.

For comparisons with closest congeners, see general discussion.

Figures

Fig. 3. A, B, Geosesarma dennerle, new species, holotype male (14.4 × 14.0 mm) (MZB 4061), Cilacap, Java; C, D, G. hagen, new species, holotype male (13.9 × 13.3 mm) (MZB 4062), Cilacap, Java. A, C, overall view; B, D, dorsal view of carapace.

Fig. 4. A–G, Geosesarma dennerle, new species, holotype male (14.4 × 14.0 mm) (MZB 4061), Cilacap, Java; H–M, G. hagen, new species, holotype male (13.9 × 13.3 mm) (MZB 4062), Cilacap, Java. A, H, left third maxilliped; B, I, male abdominal somites 3–6 and telson; C–G, J–M, left G1 (drawn from different angles). All structures denuded. Scale bars = 1.0 mm.

Fig. 5. A, B, Geosesarma noduliferum (De Man, 1892), lectotype male (11.4 × 10.9 mm) (RMNH 1246a), Bogor, Java; C, G. bicolor Ng & Davie, 1995, holotype male (11.0 × 10.5 mm) (ZRC 1995.279), Ujung Kulon, Java; D, F, G. dennerle, new species, holotype male (14.4 × 14.0 mm) (MZB 4061), Cilacap, Java; E, G, G. hagen, new species, holotype male (13.9 × 13.3 mm) (MZB 4062), Cilacap, Java; H, I, G. confertum (Ortmann, 1894), male (10.7 × 9.7 mm) (ZRC 1970.3.7.11), Tjibodas, Java. A, H, anterior male thoracic sternum and abdomen; B–E, I, outer surface of right chela; F, G, left last ambulatory leg

Fig. 6. Colours in life. A–C, Geosesarma dennerle, new species, Cilacap, Java; D–F, G. hagen, new species, Cilacap, Java. A, B, specimens from type series; C, male (13.1 × 11.7 mm) (ZRC 2014.0271). A, B: 7°25’59”S, 108°55’50”E, Cilacap, Java; F, 7°27’50”S, 108°50’16”E, Cilacap, Java; C–E, from aquarium trade, from Cilacap, Java (Photographs: Chris Lukhaup [A, B, F]; Tan Heok Hui [C]; Oliver Mengedoht (specimens not preserved) [D, E]).

Fig. 7. A, type locality of Geosesarma dennerle, new species; B, burrows by the side of a stream bank dug by of G. dennerle, new species; C, a young female G. dennerle, new species, on the stream bank; D, type locality of G. hagen, new species; E, adult G. hagen, new species, on bank of stream; F, an adult male of G. hagen, new species, on moss covered stream bank. A–C: 7°25’59”S, 108°55’50”E, Cilacap, Java; D–F, 7°27’50”S, 108°50’16”E, Cilacap, Java. Specimens not preserved (Photographs: Chris Lukhaup).