Species Tree Inference, Genetic Species Delimitation, and Species Descriptions in the Sitalcina sura Species Group (Opiliones, Laniatores, Phalangodidae)
The western United States is home to numerous endemic harvestmen (Arachnida, Opiliones), including members of the genus Sitalcina. Prior to this study, very limited genetic data was available for Sitalcina species and previous phylogenetic studies focused only on broad relationships within the genus, not on closely related species. Genetic data are well suited for testing species limits in the Sitalcina sura group because these dispersal-limited arachnids show minimal gene flow between morphologically conserved populations, resulting in possible cryptic speciation. Here, molecular phylogenetic and species delimitation analyses were conducted for all species in the S. sura group, plus several newly discovered populations. Species trees were reconstructed using multispecies coalescent-based methods implemented in *BEAST. Species delimitation was accomplished using the program BP&P, as well as Bayes Factor Delimitation. Genetic analyses using DNA sequence data from seven genes delimit 13 species in the S. sura group, adding four new species. New species were formally described using a combination of molecules and morphology. Molecular phylogenetic evidence revealed distinctive desert versus coastal clades. Conservation may be an important issue for several species within the S. sura group given their restricted endemic distributions, and defining operational taxonomic units provides a foundation for future conservation efforts.
