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| Mekhongthelphusa menglongensis Pan, Yeo & Sun, 2021 |
Abstract
A new gecarcinucid freshwater crab, Mekhongthelphusa menglongensis sp. nov., is described from Menglong Town, Jinghong City, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China. This is the first report of the mainly Indochinese genus Mekhongthelphusa Naiyanetr, 1994, in China. The new species can be distinguished morphologically from the other four nominal species in this genus by its carapace and male first gonopod. The mitochondrial 16S sequences of this new species are provided and the phylogenetic position of the genus is discussed.
Keywords: 16S rDNA; Indochina; morphology; taxonomy; Xishuangbanna
Family Gecarcinucidae Rathbun, 1904
Genus Mekhongthelphusa Naiyanetr, 1994
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| Mekhongthelphusa menglongensis sp. nov., holotype male (35.1 × 30.4 mm) (NNU 16C-MM01) (A-F, H); paratype female (34.7 × 28.9 mm) (NNU 16C-MM03), (G, I). A, Male dorsal view; B, male ventral view; C, male front view; D, male major cheliped; E, male minor cheliped; F, male pleon; G, female pleon; H, male sterno-pleonal cavity; I, female thoracic sternum and vulvae. Scale bars = 1 cm. |
Mekhongthelphusa menglongensis sp. nov.
Diagnosis. Carapace trapezoidal, slightly broader than long, dorsal surface smooth, slightly convex; posterolateral margins gently converging; H-shaped groove distinct; epigastric cristae distinctly anterior of postorbital cristae, outer edge slightly overlapping inner edge of postorbital cristae; postorbital cristae distinct, entire, sharp, very gently sinuous, curving obliquely posterolaterally, reaching but not confluent with base of third epibranchial teeth; anterolateral margin with 3 distinct epibranchial teeth. Third maxilliped ischium rectangular, pitted; exopod long, reaching beyond midpoint of merus, with long, well-developed flagellum. Male pleon T-shaped, somites 5 and 6 together constricted medially, with lateral margins concave. Male chelipeds strongly asymmetrical, cutting edge lined with small, rounded teeth, gap distinct when fingers closed. G1 strongly curved outwards, distal part slender, tip longitudinally twisted, slightly bent, distinctly hooked in appearance, basal part dilated up to least half length of G1, with broadest part approximately one-third length of G1.
Etymology. The species name is derived from the type locality, Menglong Town, Jinghong City, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China.
Habitat. Specimens were found in a small gravel-bed river, slightly turbid, slow flowing, about 5 m in width. The crabs were collected from the middle of the river.
Distribution. The species is so far only known from Menglong Town, Jinghong City, Xishuangbanna Dai Autonomous Prefecture, Yunnan Province, China.
Da Pan, Darren C.J. Yeo and Hongying Sun. 2021. On A New Species of Freshwater Crab of the Genus Mekhongthelphusa Naiyanetr, 1994 (Decapoda: Brachyura: Gecarcinucidae) from south Yunnan, China. Nauplius. 29; DOI: 10.1590/2358-2936e2021050