Prorachias Mello-Leitão, 1924 is known only from its type-species Prorachiasbristowei Mello-Leitão, described based on a female from the state of Rio de Janeiro, Brazil. The description is very short and incomplete and some important characters, such as the shape of the spermathecae, are omitted. The type specimen, that should be deposited in the collection of the Museu Nacional do Rio de Janeiro, was not located and is probably lost. Nevertheless, specimens collected by the project "Biodiversity of Arachnida and Myriapoda of the State of São Paulo" and deposited in the collection of the Butantan Institute enabled to improve the diagnosis of the genus as well as describe the species' male. In addition, notes on the biology are presented and the distribution range is extended to the states of Goiás, Minas Gerais and São Paulo.
Araneae; Nemesiidae; Prorachias bristowei; spiders; systematic
