Callosa gen. n., a new troglobitic genus from southwest China (Araneae, Linyphiidae).

A new linyphiid genus Callosa gen. n. , with two new species Callosa ciliata sp. n. (♂♀, type species) and Callosa baiseensis sp. n. (♂♀), from southwest China are described. Detailed description of genitalic characters and somatic features is provided, as well as light microscopy and SEM micrographs of each species. Callosa gen. n. was found in caves in Yunnan and Guangxi, and its copulatory organs are similar to those of Bathyphantes and Porrhomma , but differ greatly in details. The monophyly and placement of Callosa gen. n. are supported by the results of molecular analysis.