UCE phylogenomics of New World Cryptopone (Hymenoptera: Formicidae) elucidates genus boundaries, species boundaries, and the vicariant history of a temperate-tropical disjunction

Authors: Branstetter, Michael; LONGINO, JOHN - University Of Utah

Submitted to: Insect Systematics and Diversity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2021
Publication Date: 1/25/2022
Citation: Branstetter, M.G., Longino, J.T. 2022. UCE phylogenomics of New World Cryptopone (Hymenoptera: Formicidae) elucidates genus boundaries, species boundaries, and the vicariant history of a temperate-tropical disjunction. Insect Systematics and Diversity. 6(1):1-23. Article 6. https://doi.org/10.1093/isd/ixab031.
DOI: https://doi.org/10.1093/isd/ixab031

Interpretive Summary: UCE phylogenomics of New World Cryptopone (Hymenoptera: Formicidae) elucidates genus boundaries, species boundaries, and the vicariant history of a temperate-tropical disjunction: A major challeng to identifying species in diverse insect groups is lack of visible differences. The ant genus Cryptopone is a challenging for this reason, being difficult to identify at both the genus and species levels. Focusing on species in the Americas, molecular data from ultraconserved elements (UCEs) were used to build a family tree and then test genus and species boundaries based on the results. The data were also used to explore biogeographic patterns in the region. The results showed that the genus Cryptopone represented three unrleated groups of ants and multiple species in the Americas. Based on this information the genus was redefined, an old genus name was resurrected, and three new species were described. The study improves knowledge of ant biodiversity in the Americas and shows how UCE phylogenomic data can be used to address different questions in insect systematics. The study also provides new information on insect biogeography in North and Central America.

Technical Abstract: The genus Cryptopone Emery contains 25 species of small leaf litter and soil ants, 5 of which occur in the Americas. The species C. gilva occurs in the southeastern U.S.A. and the cloud forests of Mesoamerica, exhibiting an uncommon biogeographic disjunction observed most often in plants. We used phylogenomic data from ultraconserved elements (UCEs), as well as mitogenomes and legacy markers, to investigate phylogenetic relationships, species boundaries, and divergence dates among New World Cryptopone and a selection of outgroups. Species delimitation was conducted using a standard approach and then tested using several model-based molecular methods (SNAPP, BPP, SODA, and bPTP). We found that Cryptopone as currently constituted is polyphyletic, and that all the South American species belong to Wadeura Weber, a separate genus unrelated to Cryptopone. We also found that a single clade of true Cryptopone occurs in the Americas, and that it is restricted to North and Central America. This clade is itself composed of four cryptic species that originated ~4.2 million years ago. One species from the mountains of Guatemala is sister to the other three, favoring a vicariance hypothesis of diversification. The taxonomy of the New World Cryptopone and Wadeura are revised. Taxonomic changes are: the genus Wadeura Weber is resurrected and contains the previously described species W. guianensis Weber (rev. comb.), W. holmgreni (Wheeler) (n. comb.), and W. pauli (Fernandes & Delabie) (n. comb.); C. guatemalensis (Forel) (rev. stat.) is raised to species, and includes the junior synonym C. obsoleta (Menozzi) (syn. nov.). The following new species are described: Cryptopone gilvagrande, C. gilvatumida, and Wadeura holmgrenita. Cryptopone hartwigi is transferred to Fisheropone (n. comb.). Cryptopone mirabilis (Mackay & Mackay 2010) is a junior synonym of Centromyrmex brachycola (Roger) (syn. nov.).