Monday, May 25, 2020

[Crustacea • 2020] Qianguimon yuzhouense • A New Species of Freshwater Crab of the Genus Qianguimon Huang, 2018 (Decapoda: Brachyura: Potamidae) from Guangxi, Southern China


Qianguimon yuzhouense
 Wang, Zhang & Zou, 2020
Photos: Chao Huang.

Abstract
A new species of freshwater crab of the genus Qianguimon Huang, 2018, is described from Guangxi Zhuang Autonomous Region, southern China. It can be distinguished from congeners by the following characters: male first gonopods bent inward at about 45° at base of terminal segment, carapace regions distinct and rugged and the female vulva opening inwards and downwards. In addition, molecular evidence derived from the 16S rRNA gene supported the species described in this study as a new species of Qianguimon.

Figure 6: Qianguimon yuzhouense n. sp. Habitat environment.
(A and B) Color in life; (C) a burrow inhabited by the new species (indicated by circle); (D) collecting specimens by hand.
Photos: Chao Huang.

Systematics
Family Potamidae Ortmann, 1896

Qianguimon Huang, 2018

Qianguimon yuzhouense n. sp.

Diagnosis. Carapace broader than long, regions distinct, anterolateral regions rugose; cervical groove and H-shaped groove deep, distinct; epigastric cristae conspicuous, postorbital cristae sharp. External orbital angle narrowly triangular, separated from anterolateral margin by gap; epibranchial teeth distinct; anterolateral margin lined with conspicuous granules. Third maxilliped merus median depression indistinct, exopod with vestigial flagellum. Chelipeds slightly unequal; outer surfaces of chelae smooth; fingers with very small gap when closed. Male pleon narrowly triangular, lateral margins gently concave; telson triangular, somite 6 transversely trapeziform. Male sterno-pleonal cavity very deep, median longitudinal suture of sternites 7/8 deep and relatively long. G1 very slender, terminal segment boot-shaped, distinctly sinuous, tip of terminal segment exceeding sternites 4/5 suture. Female vulva reaching sternites 5/6 suture, with opening directed inward at an angle of 45°.




Etymology. The new species is named after the type locality, Yuzhou District, Yulin City, Guangxi Zhuang Autonomous Region, China.

Ecology. This species was found in a stream next to a mountain road. The stream has no obvious flowing water, and has lush weeds growing in it. We found the crab burrows by removing the weeds. The burrows are sandy and without much soil. We found the crabs after digging about 10 cm into the burrows (Figs. 6C and 6D).


Conclusions: 
In this article, we reported a new species of freshwater crab from Yuzhou District, Yulin City, Guangxi Zhuang Autonomous Region, China. We found that it fits well within the definition of Qianguimon Huang, 2018, morphologically, and our molecular analysis also supports it as a new species of the genus Qianguimon.


Song-Bo Wang, Ya-Nan Zhang and Jie-Xin Zou​. 2020. A New Species of Freshwater Crab of the Genus Qianguimon Huang, 2018 (Decapoda: Brachyura: Potamidae) from Guangxi, Southern China. PeerJ. 8:e9194. DOI: 10.7717/peerj.9194