Geothelphusa makatao from SW Taiwan

Geothelphusa makatao sp. nov. (Crustacea: Brachyura: Potamidae), a new freshwater crab from an uplifted Pleistocene reef in Taiwan

Hsi-Te Shih & Jhy-Yun Shy

A new species of potamid freshwater crab, Geothelphusa makatao, is described from southwestern Taiwan, based on morphological characters and mitochondrial DNA evidence. The new species differs from close congeners, G. pingtung Tan & Liu, 1998, G. shernshan Chen, Cheng & Shy, 2005, and G. ancylophallus Shy, Ng & Yu, 1994 and a superficially similar species, G. albogilva Shy, Ng & Yu, 1994, in the structure of its ambulatory legs, thoracic sternum, male abdomen, and male first pleopods. The unique gene sequences of 16S rRNA and cytochrome oxidase I also support the recognition of this coastal population, which is isolated from other closely related species inhabiting montane areas. Except for G. makatao, the phylogenetic analysis showed that there are three additional hill subclades within the G. pingtung clade, G. shernshan, G. pingtung and the Liangshan subclade, situated in different watersheds of rivers or streams near the Central Range in the southwestern Taiwan.

Key words: 16S rRNA, cytochrome oxidase I, Geothelphusa makatao, G. pingtung, Brachyura, Potamidae, Taiwan, taxonomy, new species

FIGURE 1. Male right first and second pleopods of Geothelphusa makatao sp. nov. (holotype, NMNS-5915001). a, G1, ventral view of right G1; b, terminal segment of G1; c, dorsal view of right G1; d, ventral view of right G2. Scale = 0.5 mm.

FIGURE 2. Geothelphusa makatao sp. nov. a, dorsal view of the holotype (NMNS-5915-001); b, frontal view of the holotype; c, ventral view of the holotype; d, e, live coloration of a male, dorsal view; f an individual eating mud; g, a female with brood in a natural habitat (the campus of National Sun Yat-sen University); h, habitat in a dry creek bed where individuals were hidden under rocks (near Longcyuan Temple, Chaishan).

FIGURE 3. A minimum evolution (ME) tree of the Geothelphusa pingtung clade, with the outgroup, G. ancylophallus, in southwestern Taiwan based on 1164 bp of the combined 16S rRNA and cytochrome oxidase I (COI) genes. Probability values at the nodes represent confidence values for ME, maximum parsimony (MP), Bayesian inference (BI), and maximum likelihood (ML). Only confidence values of ≥ 50% are shown. An asterisk (*) with a haplotype indicates that the holotype was included.

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