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(A, D) Candidiopotamon rathbuni (De Man, 1914) and (E–H) Candidiopotamon penglai Shih, Naruse & Schubart, 2023 |
Abstract
A new freshwater crab of the potamid genus Candidiopotamon Bott, 1967, is described from eastern Taiwan. Candidiopotamon penglai sp. nov. is morphologically similar to C. rathbuni (De Man, 1914) from western Taiwan, but can be distinguished by the morphology of the male first gonopod (G1), as well as by their mitochondrial DNA (16S rRNA and COI genes). In the G1 of C. rathbuni, the subterminal segment shows a cline from robust in northern populations to slender in southern populations. In the G1 of C. penglai sp. nov., a distinctly larger and more distally directed keel-like projection is found on the distal inner edge of the terminal segment, with northern populations having an inward-curving subterminal segment and southern populations a straight subterminal segment. The genetic differentiation of the two species of Candidiopotamon within Taiwan is discussed, and morphological differences are compared. A key to the species of Candidiopotamon is also provided.
Key words: 16S rDNA, Candidiopotamon penglai, Candidiopotamon rathbuni, cytochrome oxidase subunit I, Decapoda, morphology, new species, taxonomy
Family Potamidae Ortmann, 1896
Subfamily Potamiscinae Ortmann, 1896 (sensu Yeo and Ng 2004)
Genus Candidiopotamon Bott, 1967
C. penglai sp. nov. (eastern Taiwan)
C. rathbuni (De Man, 1914) (western Taiwan)
C. okinawense Minei, 1973 (Okinawa Island, Japan)
C. tokashikense Naruse, Segawa & Aotsuka, 2007 (Tokashiki Island, Japan)
C. kumejimense Minei, 1973 (Kumejima Island, Japan)
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| Color in life of Candidiopotamon rathbuni (De Man, 1914) (A, B) and Candidiopotamon penglai sp. nov. (C–F). A, C, E overall dorsal view B, D, F overall ventral view A, B NCHUZOOL 15181 (male, 28.0 × 23.9 mm, Rihyuetan, Nantou, western Taiwan) C, D NCHUZOOL 15204 (male, 39.7 × 34.4 mm, Nanrenshan, Pingtung, southern Taiwan); NCHUZOOL 15224 (paratype male, 36.4 × 30.9 mm, Liyu Lake, Shoufeng, Hualien, eastern Taiwan). |
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| Color in life of Candidiopotamon rathbuni (De Man, 1914) (A–D) and Candidiopotamon penglai sp. nov. (E–H). A, B NCHUZOOL 15194 (male, 35.4 × 31. 2 mm, Tai-an, Miaoli, northwestern Taiwan) C NCHUZOOL 15211 (male, 24.8 × 22.1 mm, Dongshih, Taichung, western Taiwan) D NCHUZOOL 15181 (male, 28.0 × 23.9 mm, Rihyuetan, Nantou, western Taiwan) E, F NCHUZOOL 15204 (2 males, 39.7 × 34.4 mm, 40.6 × 34.3 mm, Nanrenshan, Pingtung, southern Taiwan) G NCHUZOOL 15224 (paratype male, 36.4 × 30.9 mm, Liyu Lake, Shoufeng, Hualien, eastern Taiwan) H NCHUZOOL 15229 (male, 33.1 × 29.7 mm, Jili Lake, Guangfu, Hualien, eastern Taiwan). |
Candidiopotamon penglai sp. nov.
Diagnosis: Carapace subtrapezoidal, CW 1.14–1.24× CL (mean 1.18, n = 45), dorsal surface almost flat, relatively rough, epigastric and postfrontal cristae distinct, both cristae represented by 1–3 oblique lines of granules, lateral end of postfrontal cristae far apart from epibranchial tooth; external orbital and epibranchial teeth distinct, sharp, directed anteriorly. G1 terminal segment proportionally longer and slender, distal opening directed laterally, distal inner edge with keel-like projection in dorsal view, projection proportionally large, directed more distally; G1 subterminal segment curving inwards (in eastern to southeastern Taiwan populations) or straight (in southern Taiwan populations).
Etymology: The new species is named after Penglai, the ancient name of Taiwan. It also refers to the fact that the island of Taiwan was formed by the Penglai Orogeny (ca 5 million years ago) (Teng 1990; Liu et al. 2000), and the ancestral Candidiopotamon most likely colonized Taiwan at that time (Shih et al. 2006). The species name is used as a noun in apposition.
Hsi-Te Shih, Tohru Naruse and Christoph D. Schubart. 2023. Molecular Evidence and Differences in Gonopod Morphology lead to the Recognition of A New Species of the Freshwater Crab Genus Candidiopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) from eastern Taiwan. ZooKeys. 1179: 157-168. DOI: 10.3897/zookeys.1179.108759
