title: Phylogenetic relationships of Loxosceles and Sicarius spiders are consistent with Western Gondwanan vicariance.
abstract: The modern geographic distribution of the spider family Sicariidae is consistent with an evolutionary origin on Western Gondwana. Both sicariid genera, Loxosceles and Sicarius are diverse in Africa and South/Central America. Loxosceles are also diverse in North America and the West Indies, and have species described from Mediterranean Europe and China. We tested vicariance hypotheses using molecular phylogenetics and molecular dating analyses of 28S, COI, 16S, and NADHI sequences. We recover reciprocal monophyly of African and South American Sicarius, paraphyletic Southern African Loxosceles and monophyletic New World Loxosceles within which an Old World species group that includes L. rufescens is derived. These patterns are consistent with a sicariid common ancestor on Western Gondwana. North American Loxosceles are monophyletic, sister to Caribbean taxa, and resolved in a larger clade with South American Loxosceles. With fossil data this pattern is consistent with colonization of North America via a land bridge predating the modern Isthmus of Panama.
authors.affiliation: Department of Biology, Lewis & Clark College, 0615 SW Palatine Hill Road, Portland, OR 97219, USA. binford@lclark.edu
authors.forename: Greta J
authors.initials: GJ
authors.lastname: Binford
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Callahan
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Bodner
authors.forename: Melody R
authors.initials: MR
authors.lastname: Rynerson
authors.forename: Pablo Berea
authors.initials: PB
authors.lastname: Núñez
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Ellison
authors.forename: Rebecca P
authors.initials: RP
authors.lastname: Duncan