Phylogeny, Ecology, and Taxonomic Revision of the Travertine Beetles (Coleoptera: Lutrochidae)

Abstract

The Lutrochidae is a small, poorly known group of aquatic beetles, endemic to the Western Hemisphere. The evolutionary history of the group has never been examined in a phylogenetic framework, and much of its diversity is undescribed. Here, I present the first phylogenetic study of the group and a revised classification, which better reflects the evolutionary relationships in light of an extensive review of museum material. Bayesian and Maximum Likelihood phylogenetic analyses of three genes (16S, 28S, and COI) strongly supported a close relationship with Dryopidae, which is consistent with published literature. However, the placement of the dryopid Ceradryops spp. as sister to Lutrochidae renders Dryopidae paraphyletic. These same molecular phylogenetic analyses of the group recovered distinct, well-supported clades within Lutrochidae, which are corroborated by morphology, distribution, and ecology. As a result, the taxonomy of the group is revised to reflect evolutionary relationships recovered in phylogenetic analyses, and the following genera are erected: Andotrochus n. gen., from Andean South America; Auritrochus n. gen., from North and northern Central America; Berotrochus n. gen., from the Greater Antilles; and Saxitrochus n. gen., from Andean South America. The genus Andotrochus n. gen. includes the species Andotrochus minutus (Maier & Short, 2013) n. comb. The genus Auritrochus n. gen. includes the species Auritrochus arizonicus (Brown and Murvosh, 1970) n. comb., Auritrochus laticeps (Casey, 1893) n. comb., and Auritrochus luteus (LeConte, 1852) n. comb. The genus Berotrochus n. gen. includes Berotrochus geniculatus (Chevrolat, 1864) n. comb. The genus Saxitrochus n. gen. includes Saxitrochus meridaensis (Maier and Short, 2013) n. comb. The composition of Lutrochus sensu. n. is revised to include only species from South and southern Central America that have a close association with submerged woody debris. Morphological phylogenetic analyses recovered a tree with similar topology to the molecular analyses. Most branches were poorly supported, and a thorough re-evaluation of homology statements and character selection is necessary, and inferences about the group based on morphology can not be using the data in its current state. Examination of museum specimens revealed eight species, new to science: Andotrochus cordobensis n. sp. from Argentina; Auritrochus brunneus n. sp. from southern Mexico; Auritrochus shepardi n. sp. from Mexico; Lutrochus barrae n. sp. from Central America; Lutrochus gimmeli n. sp. from Ecuador; Lutrochus guarani n. sp. from Paraguay; Lutrochus tocache n. sp. from South America; and Lutrochus torrens n. sp. from Central America. These species are described and descriptions, illustrations, photographs of historical type specimens, diagnoses, distribution maps for all twenty-nine species, including previously described species, are provided. An illustrated key to species of Lutrochidae of the world is also presented. A catalogue of world Lutrochidae species is included, and lectotypes are designated for the following species: Lutrochus montanus Grouvelle, Lutrochus pilula Erichson, and Lutrochus geniculatus Chevrolat.