A new Mexican species of the Cryptopygus complex (Collembola, Isotomidae) associated with the hermit crab Coenobitaclypeatus (Crustacea, Coenobitidae).

A new species of Cryptopygus Willem, 1901 associated with hermit crabs living on seashores of Quintana Roo State, Mexico, is described and illustrated. It is blind, with 9-11 postlabial setae, unguis with a pair of lateral teeth, empodial appendix lanceolate and almost as long as unguis, tenaculum with 4 + 4 teeth and 3-4 setae on corpus, manubrium with 11-14 pairs of manubrial setae on anterior surface and 17-18 pairs on posterior surface, and mucro bidentate. An updated key for the identification of 29 American species of Cryptopygus complex is included.