New species of Monodontocerus (Collembola: Tomoceridae) from southern China with diagnostic notes on the genus and introduction of new taxonomic characters.

Three new species of Monodontocerus are described from caves in southern China: M. absens sp. nov. is characterized by its cephalic chaetotaxy and the absence of chaetae from the tenaculum; M. mulunensis sp. nov. is characterized by a combination of characters including chaetotaxy, foot complex and furca; M. trigrandis sp. nov. is different from other species in the formula of dental spines and the reduction of the ungual teeth. A key to the species of Monodontocerus is provided. Potential diagnostic characters for this genus are proposed. Troglomorphy and interspecific variability are discussed. Pseudopores and the dorsal disto-lateral chaeta on the manubrium are introduced as new taxonomic characters for Tomocerinae.