BIOLOGICAL RELATIONSHIPS OF PENTASTOMIDA - A BIBLIOGRAPHY ON PENTASTOMIDA

The Pentastomida constitute an aberrant group of helminths which, like the onycophora, have lost most affinities to other major classes. Superficial acarin resemblances are thought to reflect larval adaptations only. Modern studies suggest that the pentastomes share both arthropod and annelid characters but that one cannot justify assigning them to either phylum. They are, therefore, assigned the status of an independent phylum with the belief that they share a common ancestry with the Annelida and Arthropoda. It appears that, initially, the pentastome ancestors invaded the respiratory cavities of reptiles thus indicating that they were probably land animals. The adoption of insects and mammals as secondary hosts seems to have been secondary. There are two orders. The Cephalobaenida are the more primitive and their life cycles involve insects, fish, amphibia, and reptiles as secondary hosts. There is evidence that some can complete direct life cycles in a single reptilian host species and this is considered the most primitive situation. All the Porocephalida except one require mammals as secondary and reptiles as definitive hosts. Species of Linguatula complete the cycle entirely in mammals. The porocephalids are considered to be more highly evolved than the Cephalobaenida. © 1969.