The female of Pterygosoma aegyptiaca Mostafa, 1974 (Acariformes: Prostigmata: Pterygosomatidae) is redescribed. This species, previously known only from its type locality (Egypt) and type host (Uromastyx sp.), is newly recorded from Sudan and from the ocellated spinytail, Uromastyx ocellata Lichtenstein. An unstriated area of idiosomal cuticle is proposed as a prodorsal shield, a character not previously attributed to the genus. Two pairs of idiosomal lyrifissures, ip and ih, are identified in Pterygosoma Peters, 1849, for the first time, as is a distal microseta (kappa) on leg genu I. A dorsal structure observed near the base of the leg tarsi is considered to be a lyrifissure (= proprioceptor) and is newly recorded in the Pterygosomatidae. In the light of these new morphological observations and of character states described recently by other authors, amendments to the diagnosis and definition of adult Pterygosoma are proposed. Questions are raised about the conspecificity of presumed syntypes of P. persicum Hirst, 1917, and of specimens of P. tuberculata Jack, 1962a, identified by its author. The number of idiosomal lyrifissures present in Geckobiella diolii (Baker, 1998) (new combination for Hirstiella diolii by Paredes- Leon et al. (2012)) is corrected from four to two.
