Wing Condition and Distribution of a Mesoamerican Montane Genus of Wooddegrading Beetles, Oileus Kaup (Coleoptera: Passalidae), with the Description of a New Species.

Abstract

Distribution areas, in terms of size and shape, are usually related to dispersal capacity, and the latter is partly related to flight capacity in insects. Thus, wing condition (brachypterous or macropterous) is expected to correlate with the area size of the species distribution range. Here, we studied this aspect for the first time in Passalidae, a subsocial group of saproxylophagous beetles. To obtain the geographic distribution of species, we performed species distribution models in the Mesoamerican genus Oileus, which has seven species (including one new species from Oaxaca, Mexico) restricted to either side (west or east) of the Isthmus of Tehuantepec (except for Oileus rimator which is distributed in both sides of the Isthmus). Species distribution models were used to estimate biogeographic affinities among species and to compare the potential distributional area with respect to the species wing condition (four brachypterous and three macropterous). Additionally, we described the sound-emitting structures (plectrum, region located on hind wings) for all Oileus, being the first study describing it for all species of the same genus. Macropterous species tend to have larger potential distribution areas (between 149,027-364,107 km²) than brachypterous species (9,063-15,716 km²), and all brachypterous species inhabit montane areas. These results coincide with what would be expected if the loss of flight capacity reduced dispersal capacity. However, because of the limited data, we could not statistically test this relationship. Future analyses should evaluate the relationship between passalid species distributions (total area and elevation) and wing morphology, including species with narrow and wide distributions, both altitudinally and latitudinally.