GASTROINTESTINAL HELMINTHS OF NIGHT LIZARDS, GENUS XANTUSIA (XANTUSIIDAE)

Examination of the gastrointestinal tracts of 278 Xantusia vigilis, 40 Xantusia henshawi, and 8 Xantusia bolsonae revealed the presence of 1 species of nematode, Parapharyngodon californiensis (prevalences 1, 2 8, and 50%, respectively). Xantusia henshawi and X. vigilis also harbo red 1 species of cestode, Oochoristica bezyi (prevalences 35 and 16%, respectively). Xantusia bolsonae is a new host for P. californiensis. Xantusia henshawi and X. vigilis are new hosts for 0. bezyi. Examinati on of the gastrointestinal tracts of 21 Xantusia riversiana revealed t he presence of 6 species of nematodes: Alaeuris clementensis, Alaeuris riversianae, Parapharyngodon pseudothaparius, Parapharyngodon xantusi , Thubunaea iguanae, and an unidentified oxyurid (prevalences 71, 81, 100, 90, 14, and 5%, respectively). One species of cestode, Oochoristi ca islandensis (prevalence 52%), also was present. Xantusia riversiana is a new host for T. iguanae. Compared to the mainland species of Xan tusia, the helminth fauna of the insular X. riversiana is both unique and diverse. The high prevalences of helminths in X. riversiana may be due to the increased opportunity for infection and reinfection presen ted by its unusually dense populations and overlapping home ranges.