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Search the Web | Systematics and Phylogenetics
History of Systematics:
In 1758 the Chiton was accepted as a genus and a short description of only four species had been made. Then in 1767 four additional species were able to be identified, two of which are still valid today. By the end of the 18th century publication began to see the importance of identification by anatomic details in the "soft" part of the Chitons and not purely by the shell plates, this allowed for to identification of 4 more species. The first systematic classification was attempted at the beginning of the 1900's which allowed for the creation of a new classification system. This new classification system lead to the identification of nearly 200 new species. The second half of the 19 century saw some important published works on Chitons. Pilsbry identified 500 different species through his work, and produced important illustrations. He also introduced a new classification scheme, involving 3 superfamilies, 6 families, 38 genera. and 27 subgenera. the 2000's provided us with important advances in systermatics. Thiele proposed a new classification system and created the suborders Lepidopleurina and Chitonina, with authors from all over the world now contributing to the growing literature of this now class polyplacophora (Dell’Angelo & Smriglio 2001).
Phylogenetics:
In 1987 the class polyplacophora was divided up into 3 subclasses:
- Paleoloricata
- Phosphatoloricata
- Neoloricata
In 1997 this was reduced to two lineages:
- Paleoloricata
- Neoloricata (more highly derived)
All extant Chitons belong to Neoloricata, whereas fossil species are classified within both groups (Yates et al 1992, Dell’Angelo & Smriglio 2001). |
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