A new genus of Neelidae (Collembola) from Mexican caves.

The new genus Spinaethorax, whose proposal is based on specimens of Megalothorax spinotricosus Palacios-Vargas & Sánchez, 1999, is given a new name combination and a redescription. The type species comes from two caves in Campeche State, México. A new combination is also suggested for Megalothorax tonoius Palacios-Vargas & Sánchez, 1999. The new genus is similar to Megalothorax Willem, 1900 and Neelus Folsom, 1896, but it clearly differs from all genera within family Neelidae by a peculiar combination of characters and the presence of some new features, e.g. globular sensillum on Ant. III, sword-like macrosetae on oral fold. A comparative table and an identification key for all Neelidae genera as well as some summary tables of antennae chaetotaxy and legs setation for type species are provided.