Megan A. Sporre

As some of the smallest vertebrates, yet largest producers of consumed reef biomass, cryptobenthic reef fishes serve a disproportionate role in reef ecosystems and are one of the most poorly understood groups of fish.  The interrelationships of the comb-tooth blenny genus Hypleurochilus remain understudied.  Relationships for ten Hypleurochilus species are resolved using multi-locus nu- clear and mtDNA sequence data, morphological data, and mined COI barcode data. Mitochondrial and nuclear sequence data from 61 individuals collected from the western Atlantic and northern Gulf of Mexico (N. GoM) delimit seven species into a temperate clade, a tropical clade, and a third distinct lineage. This lineage, herein referred to as H. cf. aequipinnis, may represent a species of Hypleurochilus whose range has expanded into the N. GoM. Inclusion of publicly available COI sequence for an additional three species provides further phylogenetic resolution. H. bananensis forms a new eastern Atlantic clade with H. cf. aequipinnis, providing further evidence for a western Atlantic range expansion. Single marker COI delimitation was unable to elucidate the relationships between H. springeri/H. pseudoaequipinnis and between H. multifilis/H. caudovittatus due to incomplete lineage sorting. Mitochondrial data are also unable to accurately resolve the placement of H. bermudensis. However, a comprehensive approach using multi-locus phylogenetic and species delimitation methods was able to resolve these relationships. While mining publicly available sequence data allowed for the inclusion of an increased number of species in the analysis and a more comprehensive phylogeny, it was not without drawbacks, as a handful of sequences are potentially mis-identified. Overall, we find that the recent divergence of some species within this genus and potential introgression events confound the results of single locus delimitation methods, yet a combination of single and multi-locus analyses has allowed for insights into the biogeography of this genus and uncovered a potential transatlantic range expansion.