Geosesarma dennerle, 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 : 6-10

Geosesarma dennerle , new species

( Figs. 3A, B , 4 A–G, 5D, F, 6A–C, 7C)

Material examined. Holotype: male (14.4 × 14.0 mm) ( MZB 4061 ), station R605–6, north of Cilacap town , Cilacap Regency, central Java, 7°25ʹ59ʺS, 108°55ʹ50ʺE, Indonesia, coll. C. Lukhaup, 5 October 2011 . Paratypes: 1 male (11.5 × 10.6 mm), 1 female (13.1 × 11.8 mm) ( ZRC 2014.0270 ), same data as holotype ; 5 males (largest 11.0 × 10.5 mm), 2 females (larger 11.3 × 10.2 mm) ( SMF 46286) , 4 males (largest 11.5 × 10.6 mm), 2 females (larger 13.5 × 11.8 mm) ( ZRC 2014.0266 ), same data as holotype. Others : 9 males (largest 13.1 × 11.7 mm), 1 ovigerous female (12.0 × 10.6 mm, eyed eggs 1.5 mm) ( ZRC 2014.0271 ), from aquarium dealer in Cilacap town , Java, 5 May 2009 ; 2 males (14.4 × 13.2 mm, 12.5 × 12.0 mm) ( ZRC 2014 . 0274), from aquarium dealer in Cilacap town , Java, 12 April 2011 ; 4 males, 1 female ( ZRC 2014.0277 ), from aquarium dealer in Cilacap town , Java, May 2011 ; 1 male (11.8 × 10.8 mm) ( ZRC 2014.0273 ), from aquarium trade, ostensibly from Cilacap, Java, from O. Mengedoht, 9 June 2010 .

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

Colour. Adult coloration in life: violet purple to purplishbrown on anterior half of carapace and ambulatory legs; posterior half of carapace cream to yellowish-white; thoracic sternum greyish-white with grey specks in smaller specimens, but pale purple in larger specimens; abdomen dark grey to purplish grey with small spots; chelae bright purple; eyes bright yellow ( Fig. 6 A–C). While the typical colour pattern has the dorsal surface clearly demarcated into two zones, some specimens have most of the carapace cream with only the anterior edge purple. Juvenile specimens tend to have purplish-brown carapaces, with patches of yellow or brown on the anterior part ( Fig. 7C ). The bright purple chelae are present in larger adults ( Fig. 6 A–C), and occasionally in juveniles ( Fig. 7C ). In general, smaller specimens (e.g., males 9.1 × 8.5 mm, ZRC 2014.0266) possess greyish–purple to pale purple chelae, sometimes appearing almost white. Some larger males (e.g., 11.1 × 10.8 mm, ZRC 2014.0266), however, also have white chelae.

Etymology. The new species is named after the German company Dennerle, who kindly supported the third author’s study in Java. The name is used as a noun in apposition.

Ecology. These terrestrial crabs inhabit the slopes of a small valley, living under and between rocks, among the dense vegetation ( Fig. 7A ). They sometimes excavate burrows in the loose ground at the edge of the creek that runs through the valley ( Fig. 7B ). Juveniles are often observed close to the waterline on land ( Fig. 7C ). Their diet consists mainly of small terrestrial insects such as grasshoppers, and probably also chironomid larvae and plant detritus.

Remarks. Specimens obtained from the aquarium trade by Rademacher & Mengedoht (2011) identified as “ Geosesarma “Vampir” Vampirkrabbe” (p. 40) and “ Geosesarma sp. “Blue” Blaue Vampirkrabbe” (p. 41), belong to Geosesarma dennerle , new species, at least on the basis of some of their specimens examined and the distinctive colour pattern figured (with due consideration of the colour variation noted above). Their specimens of “ Geosesarma bicolor Krakatau- Vampirkrabbe” ( Rademacher & Mengedoht, 2011: 45) probably also belong to the new species. The locality for these specimens (not examined) given by the aquarium is dubious, as the island of Krakatau is an active volcano and has no permanent freshwater source.

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).