Phylogenetic treatment and taxonomic revision of the tarantula genus Aphonopelma Pocock, 1901 (Araneae, Mygalomorphae, Theraphosidae) within the United States
Hamilton, Chris A.
Type of DegreeDissertation
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This systematic study documents the taxonomy, diversity, and distribution of the tarantula spider genus Aphonopelma Pocock, 1901 within the United States. Aphonopelma is a group wherein traditional morphological characters (i.e. homogeneous) have been shown to be generally ineffective for evaluating inter- and intraspecific variation and provides one of the greatest known challenges to species delimitation in spiders. Despite their charismatic nature, the genus Aphonopelma represents a woefully understudied radiation of spider into the southwestern United States. The genus is distributed throughout the southern third of the country, ranging west of the Mississippi River to California and down into Central America. Within the past 75 years, only four major descriptive or revisionary works (Chamberlin & Ivie 1939; Chamberlin 1940; Smith 1994; Prentice 1997) have evaluated the taxonomy of Aphonopelma, but none of these studies employed an explicit phylogenetic approach to delimit species or understand relationships. Currently, the United States Aphonopelma represent 55 nominal morphological species. The principal goal of my dissertation research was to formally resolve the group’s species-level diversity by delimiting boundaries using an approach that integrates molecular data with morphology and geospatial data. My dissertation research inferred the first phylogeny of Aphonopelma, and created an integrative approach to delimiting species using multiple DNA barcoding methods. Then these hypothesized species boundaries were evaluated by developing a multi-locus phylogenomic dataset, using Anchored Enrichment. Lastly, I incorporated all of this information to assess species-level diversity and taxonomically revise the United States Aphonopelma. By conducting the most comprehensive sampling of a single theraphosid genus to date, this research has significantly broadened the scope of prior molecular and morphological investigations, finally bringing a modern understanding of the true species boundaries to this dynamic and charismatic group of spiders.