Alaeuris rinconensis n. sp. (Oxyuroidea, Pharyngodonidae) from the large intestine of the Bonaire whiptail lizard, Cnemidophorus ruthveni, is described and illustrated. Alaeuris rinconensis n. sp. represents the 13th Neotropical species assigned to the genus. It is most similar to Alaeuris iguanae in that only these 2 Neotropical species have postbulbar excretory pores; in A. iguanae, a tail filament is absent; in A. rinconensis, a tail filament is present. Two additional helminth species were found, i.e., the cestode Oochoristica iguanae and a nematode, Ozolaimus megatyphlon. Cnemidoporus ruthveni represents a new host record for the latter 2 species.