Integrative taxonomy of genus Electrogena (Ephemeroptera: Heptageniidae): the role of innovative morphological analyses for species delimitation

Abstract

The easy, fast and correct identification of species is a crucial aspect of biology and its applications, such as biomonitoring and nature conservation. One of the groups that are common but not easily to identify are mayflies at the larval stage. In recent years, many attempts to species identification using modern and non-traditional methods have been made. Two different approaches are used in most cases: i) DNA taxonomy and ii) modern image processing and classification. In this study, we combined both to describe the intrageneric genetical and morphological variability of the Central European representatives of the genus Electrogena Zurwerra & Tomka, 1985 – one of several mayfly groups with unclear taxonomy. We compared the classical morphometric method for Electrogena species identification with non-traditional Fourier shape descriptor analysis. In particular, we used Linear Discriminant Analysis and Fourier analysis to distinguish among operational taxonomic units defined by generalised mixed Yule-coalescent (GMYC) approach based on cytochrome c oxidase subunit I (cox1) barcoding gene. Our results demonstrate that the use of modern morphometric methods can significantly improve the proportion of correctly identified individuals to species level. Moreover, the Fourier shape descriptor based analysis revealed with a remarkably low error rate the geographically separated sub-species within the genus Electrogena. Our findings show the possibility of computer-aided mayfly (and possibly other insect orders) taxa identification based on selected body part shapes. These approaches might significantly improve routine invertebrate identification and comparability of identification results across different countries and/or among research teams. Better identification can in turn lead to higher robustness of metacommunity studies, ecological status assessment and other science and practice targeted studies based on invertebrate sampling and identification.