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| Geosesarma wongi |
Abstract
A new species of semiterrestrial freshwater crab is described from Tapah Hills in Peninsular Malaysia. Geosesarma wongi sp. nov. is the 13th member of the genus reported from the country and is most similar to G. peraccae (Nobili, 1903) and G. cataracta Ng, 1986, but easily separated by its distinct carapace features and structures of the adult male chela and male first gonopod. The types of G. peraccae are figured for the first time. Geosesarma cataracta is also figured in detail, and the type series is shown to be mixed.
Key words: Comparative taxonomy, freshwater crab, Malay Peninsula, new taxon, sesarmid crab, Southeast Asia, taxonomy
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| Geosesarma wongi sp. nov., holotype male (12.7 × 11.3 mm) (ZRC 2025.0023), Perak. Colour in life. Photograph: Francis Seow-Choen. |
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| Geosesarma wongi sp. nov., holotype male (12.7 × 11.3 mm) (ZRC 2025.0023), Perak. A. Dorsal habitus; B. Dorsal view of carapace; C. Frontal view of cephalothorax; D. Ventral surface of cephalothorax. |
Geosesarma wongi sp. nov.
Diagnosis. Carapace rectangular, wider than long, width to length ratio 1.11–1.14, lateral margins almost straight, gently divergent towards posterior carapace margin (Fig. 2A, B); dorsal surfaces with well-defined regions, anterior half with prominent low, rounded tubercles and granules; postfrontal lobes distinct, median lobes with transverse row of relatively dense short setae, setae sparser on lateral lobes; epibranchial region raised; protogastric region gently convex; urogastric region raised, with gastrocardiac groove deep (Fig. 2A, B); frontal margin distinctly deflexed, frontal lobes broad, with gently convex margins in dorsal view, separated by wide shallow median concavity; postfrontal cristae sharp, distinct (Fig. 2A–C); external orbital angle triangular, directed anteriorly, not extending beyond lateral carapace margin, outer lateral margin gently convex; separated from first epibranchial tooth by V-shaped cleft; first epibranchial tooth distinct, wide, second epibranchial tooth just visible as low lobe (Fig. 2A, B); merus of third maxilliped subovate; exopod slender, flagellum elongate, longer than width of merus (Fig. 5A); outer surfaces of palm of chela covered with ...
Peter K. L. Ng. 2026. Geosesarma wongi sp. nov., A distinctive New Species of semiterrestrial crab from Tapah Hills in Perak, Peninsular Malaysia; with Notes on G. peraccae (Nobili, 1903) and G. cataracta Ng, 1986 (Crustacea, Brachyura, Sesarmidae). ZooKeys. 1266: 281-298. DOI: doi.org/10.3897/zookeys.1266.172575
