Linear and geometric morphometric analyses of variation of the plectrum in four species of bess beetles, tribe Proculini (Coleoptera: Passalidae). ARTHROPOD STRUCTURE AND DEVELOPMENT 59: 100994. DOI: https://doi.org/10.1016/j.asd.2020.100994<>
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Bess beetles are sapro-xillophagous insects that inhabit decaying logs. They display sub-social behavior and acoustic communication. Adults produce sounds with an
abdomino-alary stridulatory system. The sixth abdominal tergum has lateral
protuberances with spines ( pars stridens ) whereas the hind wings have spines in the
radial cell ( plectrum ). The potential taxonomic utility of these spines has not been
studied. We evaluated variation of spines in the plectrum of adult females sampling
four species of Proculini using traditional and geometric morphometric methods. We
divided the plectrum into five zones to compare the density, size and shape of spines
among zones and among species comparing each zone separately. Spine shape and
size were quantified with 2D cartesian coordinates and four measurements from SEM
micrographs. Separate univariate and multivariate analyses of variance revealed that
the size, density and shape of spines is different among zones in each of the four
species. Also, spine shape and size in all zones is different among species, which
would imply that plectrum spines might have taxonomic utility. Additionally, disparity
analyses showed that the peripheral zones have a higher variability, and the disparity
values in the middle and apex zones are higher in the two species with a wide
distribution range.
