Meeting Abstract

P1.130  Jan. 4  Taxonomic Status of the Widow Spider Genus Latrodectus Based on Molecular Analysis KNUTSON, V.L.*; MILLER, J.A.; University of Southern California; California Academy of Sciences

The infamous widow spiders, genus Latrodectus, have a worldwide distribution with 31 currently recognized species. The morphological characters often used in spider taxonomy tend to exhibit continuous variation within the genus and thereby prove difficult in delineating species boundaries and generally, in identifying these spiders. This underscores the importance of molecular characters in creating a valid phylogeny for this medically and ecologically important genus. The proposed tree was derived from Bayesian analysis and is based on mitochondrial gene fragments of the 16S ribosomal subunit and cytochrome c oxidase subunit I (COI). The analysis used 78 individuals of Latrodectus belonging to at least 23 different species, and one Steatoda outgroup. The tree supports the previous finding of a geometricus clade and a mactans clade, but fails to resolve the relationship between these clades and the Steatoda outgroup. The proposed tree also supports previous groupings of certain geographically proximal species such as L. katipo from New Zealand and L. hasselti from Australia that together form a clade. This phylogeny strongly supports a call for the resurrection of previously synoymized taxa such as Latrodectus scelio indica. Future research will incorporate more taxa and characters to determine what other species need to be re-evaluated and resolve remaining questions regarding the phylogeny of Latrodectus.