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| Geosesarma todaeng Ng, Yeesin & Promdam, 2023 |
Abstract
A new species of vampire crab, Geosesarma todaeng, is described from a freshwater swamp forest in Narathiwat Province, Peninsular Thailand. This lowland species belongs to the G. foxi species group and can be distinguished from congeners by its carapace, male pleon and male first gonopod features. This brings to three the number of Geosesarma species now known from Thailand. The other member of G. foxi species group that previously record in Peninsular Thailand, G. serenei is discussed.
Keywords: Decapoda, semi-terrestrial freshwater sesarmid, Geosesarma todaeng, lowland swamp forest, Peninsular Thailand
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| Geosesarma todaeng n. sp., specimens (not preserved) observed at the type locality, Narathiwat Province, Thailand, live colouration. A, overall dorsal view; B, dorsal view of carapace; C, F, frontal view of cephalothorax; D, E, chelae. |
Geosesarma todaeng n. sp.
Diagnosis.– Carapace quadrate, slightly wider than long, adult width to length ratio 1.0–1.1, lateral margins parallel (Figs. 1A, B, 2); dorsal surface with regions just visible, anterior regions with small, low rounded granules on gastric regions (Fig. 2C, D); front distinctly deflexed, 2 frontal lobes broad with almost straight margins in dorsal view; postfrontal, postorbital cristae sharp, distinct (Fig. 2C, D); external orbital tooth(= first lateral tooth)triangular, directed obliquely laterally, outer margin gently convex, tip not extending distinctly beyond lateral margin; second lateral tooth low, distinct, separated from rest of margin by wide cleft (Fig. 2C, D). Merus of third maxilliped subovate, shorter than ischium; exopod slender with no trace of flagellum (Fig. 4A). Outer surface of palm of adult male covered with small, low rounded granules and striae; inner surface granulated but without transverse ridge; dorsal margin of dactylus with7 or 8 low, non-chitinous tubercles on inner side of proximal third, proximal ones clustered together(Figs. 2A, B, 3C–G). Ambulatory legs with long, slender merus, with low subdistal spine on dorsal margin, surfaces gently rugose (Figs. 2A, B, 4C). ...
Etymology.– The name is derived from the type locality, Ban To Daeng. The name is used as a noun in apposition.
Diagnosis.– Carapace quadrate, slightly wider than long, adult width to length ratio 1.0–1.1, lateral margins parallel (Figs. 1A, B, 2); dorsal surface with regions just visible, anterior regions with small, low rounded granules on gastric regions (Fig. 2C, D); front distinctly deflexed, 2 frontal lobes broad with almost straight margins in dorsal view; postfrontal, postorbital cristae sharp, distinct (Fig. 2C, D); external orbital tooth(= first lateral tooth)triangular, directed obliquely laterally, outer margin gently convex, tip not extending distinctly beyond lateral margin; second lateral tooth low, distinct, separated from rest of margin by wide cleft (Fig. 2C, D). Merus of third maxilliped subovate, shorter than ischium; exopod slender with no trace of flagellum (Fig. 4A). Outer surface of palm of adult male covered with small, low rounded granules and striae; inner surface granulated but without transverse ridge; dorsal margin of dactylus with7 or 8 low, non-chitinous tubercles on inner side of proximal third, proximal ones clustered together(Figs. 2A, B, 3C–G). Ambulatory legs with long, slender merus, with low subdistal spine on dorsal margin, surfaces gently rugose (Figs. 2A, B, 4C). ...
Etymology.– The name is derived from the type locality, Ban To Daeng. The name is used as a noun in apposition.
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| Habitats of Geosesarma todaeng n. sp. A, B, freshwater swamp forest at the type locality, Narathiwat Province, Thailand; C, D, crab observed on the dry leaves of palm Licuala sp.(notcollected). |
Peter K. L. Ng, Pun Yeesin and Rueangrit Promdam. 2023. A New Species of Vampire Crab (Crustacea: Brachyura: Sesarmidae: Geosesarma) from A Freshwater Swamp Forest in Narathiwat Province, Southern Thailand, with A Note on Geosesarma serenei Ng, 1986. Tropical Natural History. 23(1); 97–104.
