Whole-collection COI Barcoding and Species Delimitation of Neopilionidae (Opiliones) Reveal Need for Family-wide Taxonomic Revision Open Access
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The harvestmen of the family Neopilionidae are represented by 64 described species in 20 genera and are distributed across temperate Gondwana in Chile, Argentina, southern Brazil, South Africa, Australia, and New Zealand. The family has the potential to be a valuable biogeographic model for New Zealand, but until recently neopilionid harvestmen have been taxonomically neglected, with recent work largely limited to revisions of New Zealand members of the family. We aim to supplement these revisions with molecular phylogenetic evidence in order to delimit existing species, lay the groundwork for subsequent collecting efforts, and prepare the family for use as a robust biogeographic model. We sequenced approximately 400 New Zealand neopilionid specimens from the Museum of Comparative Zoology at Harvard University, including the first neopilionid specimens found on New Caledonia, and 200 specimens from the University of Auckland for cytochrome c oxidase subunit I (COI). These data were combined with previously unpublished data from almost 100 South American specimens to create the most broadly-sampled phylogeny of Neopilionidae to date. In addition to the phylogeny, we used the multi-rate Poisson tree process to delimit species in order to test current taxonomic hypotheses about the amount of species within neopilionid genera. A number of genera and species were recovered as monophyletic with high bootstrap support values, but many were also disrupted by our analyses. In particular, Forsteropsalis and Pantopsalis taxa were dispersed in well-supported clades throughout the tree, as were Megalopsalis taxa; however, the backbone showed weak support values and had poorly resolved relationships between genera. Species delimitation analyses showed the existence of many more species than previously thought in Mangatangi, Thrasychirus, and Forsteropsalis. The majority of extant species were supported by the analyses, but we found evidence for the synonymization of P. listeri and P. cheliferoides. These results point to the need for more in depth analysis of Neoplionidae, as they contest a large amount of our current taxonomic understanding of the family. If Neopilionidae is to become a biogeographic model for New Zealand, we must continue to add morphological and molecular evidence to future analyses in order to identify new species and resolve paraphyletic genera.