SPAGNA, J.C.; GILLESPIE, R.G.: Cladistics and Biogeography of North American Grass-spiders

Grass-spiders (Araneae, Agelenidae), with their ubiquitous sheet-and-funnel-webs, are among the most common and successful families of spiders in the northern hemisphere. Cladistic analysis of genitalic and somatic morphological characters from exemplar taxa of North American agelenid genera of subfamily Ageleninae revealed a single most parsimonious tree with the configuration ((((Hololena, Novalena), Rualena), Calilena),((Agelenopsis, Barronopsis), Tortolena)), with Tegenaria used as the outgroup for rooting. The basal split between the two best-supported clades (Agelenopsis, Barronopsis, Tortolena + Hololena, Novalena, Rualena, Calilena) reflects differences in geographic distribution between their member taxa. Members of the latter clade are found throughout the Western U.S., Mexico, and Central America, while those of the former are either widespread (Agelenopsis) or restricted to Atlantic- or Gulf-coast localities. Analysis of character-state distribution and nodal support for relationships within these two clades suggests that molecular characters will be needed to improve the resolution of intergeneric and species-level relationships. This combined molecular-morphological analysis should provide a robust evolutionary framework for testing of hypotheses regarding modes of divergence, ecological divergence, character displacement, and biogeography in this ecologically important group.