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Publisher Summary This chapter describes speciation, zoogeography, and host specificity in reptilian nematodes as illustrated by studies on the genus Kalicephalus. The genus Kalicephalus with 23 known species, is reminiscent of the hookworms in life history, ecology, and morphology. The kalicephs are essentially parasites of snakes; only one poorly known species is recorded exclusively from lizards. One hundred and fifty species of snakes from all zoogeographical regions and representing most ophidian families are parasitized. Species of Kalicephalus are known from nonaquatic serpents of all tropical and warm-temperate nonarid habitats. Aquatic life provides a partial barrier to parasitism, the more highly evolved sea snakes being worm-free, and the incidence of kaliceph parasitism being low in other specialized aquatic species having intercontinental patterns of distribution. The available data suggest that there is little scope for the contemporary occurrence of many species of Kalicephalus. This is explicable on the basis of two phenomena: (1) lack of host specifity and (2) marked intolerance between cooccurring species within individual host. |
