The identity of an elusive Chilean harvestman, Pachylus crassus (Roewer, 1943) (Opiliones: Gonyleptidae: Pachylinae), with taxonomic and distribution notes.

The long-neglected Chilean harvestman species Pachylus crassus (Roewer, 1943) (Gonyleptidae, Pachylinae) is redescribed and illustrated from the types and additional material. A lectotype is designated from the original syntype series. Until now P. crassus was only known from its brief original description. Moreover, its generic affiliation remained obscure for decades, as it was successively placed in different genera until it was determined to be a member of Pachylus C.L. Koch, 1839. Aside some taxonomic remarks on the genus, it is here proposed to exclude from Pachylus one doubtful nominal species, Pachylus acanthops (Gervais, 1849), and to consider it a species inquirenda. A thorough comparison of P. crassus with its presumed close relative, P. quinamavidensis Muñoz, 1969, is provided. New records for both species and a map with all known localities of the genus are also given.