The evolution of the eastern North American isopods of the genus Asellus (Crustacea: Asellidae)

The systematics of the eastern North American isopods of the genus Asellus are revised, based on all available material (8918 specimens in 998 collections) and literature relating to eastern North American forms. Sixty-eight species (both epigean and hypogean) are recognized and discussed, five of which are newly described. Evidence is presented for synonymizing five nominal species of Asellus. A discussion is presented as to the generic status of the eastern North American isopods placed in the genus Asellus with the conclusion being reached that the proposed fragmentation of the genus is invalid (on the basis of the characters utilized). The existing species groups of troglobitic asellids have been modified and new species groups proposed for the epigean forms. The distributions of the various species groups and their individual species are given. The eastern North American isopods of the genus Asellus originated through multiple invasions of fresh water habitats primarily from early to middle Cenozoic during inundation of the coastal plains by a shallow marginal sea. Inland dispersal of these epigean ancestral stocks occurred by migration through then existing streams and rivers assisted most importantly, by the process of stream captures. Evolution of hypogean asellid stocks from epigean ancestral lineages is hypothesized. Subsequent patterns of speciation of troglobitic forms is discussed with consideration given to hypothetical barriers to dispersal.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Zoology

Department dc:contributor.department

Zoology

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1971

Author dc:creator

• Fleming, Laurence E.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10919/77832

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/77832