One hundred fifty-nine individuals of six colubrid snake species: Arizona elegans (n = 43, mean snout-vent length [SVL] = 589 mm [+ or -] 205 SD, range = 238-930 mm), Chionactis occipitalis (n = 31, SVL = 258 mm [+ or -] 20 SD, range = 222-300 mm), Masticophis flagellum (n = 12, SVL = 861 mm [+ or -] 118 SD, range 697-1104 mm), Masticophis lateralis (n = 14, SVL = 765 mm [+ or 1] 136 SD, range 520-963 mm), Phyllorhynchus decurtatus (n = 26, SVL = 357 mm [+ or -]47 SD, range = 242-469 mm), and Rhinocheilus lecontei (n = 33, SVL = 590 mm [+ or -] 93 SD, range = 362-743 mm) were borrowed from the herpetology collection of the Natural History Museum of Los Angeles County (LACM), Los Angeles, California (accession numbers, Appendix 1).
Arizona elegans and Masticophis lateralis harbored five helminth species each; Chionactis occipitalis and Rhinocheilus lecontei harbored three; Masticophis flagellum harbored two and Phyllorhynchus decurtatus harbored one helmin th species.
Arizona elegans, Chionactis occipitalis, Masticophis flagellum, Phyllorhynchus decurtatus and Rhinocheilus lecontei are sympatric in southern California and are found in dry, relatively open areas supporting chaparral, creosote bush, mesquite and sagebrush (Behler and King 1979).
Tetrathyridia have been previously found in Masticophis flagellum from Texas by Conn and McAllister (1990) and from Crotalus atrox, C.
Physaloptera abjecta was originally described from Masticophis flagellum (= Psammophis flagelliformis) from Pennsylvania by Leidy (1856).
Arizona elegans, Chionactis occipitalis, Masticophis flagellum and Rhinocheilus lecontei represent new host records.
There is some dietary overlap in these snakes: Arizona elegans feeds mainly on lizards and rodents with a few birds and snakes; Chionactis occipitalis eats insects, spiders, scorpions and centipedes; Masticophis flagellum feeds on small mammals, birds, lizards, snakes, insects and carrion; Masticophis lateralis eats frogs, lizards, snakes, small mammals, birds and insects; Phyllorhynchus decurtatus feeds on small lizards and their eggs; Rhinocheilus lecontei feeds almost exclusively on lizards (Stebbins 1985; Rodriguez-Robles et al.