Morphological, ultrastructural, and molecular identification of a new microsporidian pathogen isolated from Crepidodera aurata (Coleoptera, Chrysomelidae)

Abstract

A new microsporidian pathogen isolated from Crepidodera aurata was identified based on morphological and ultrastructuralcharacteristics, coupled with a molecular phylogenetic analysis. The spores of the microsporidian pathogen were slightly curved inshape, and measured 2.44–3.55 µm in length and 1.25–1.55 µm in width (n = 50). Its ultrastructure is characteristic of monokaryoticgroups. All lifecycle stages of the pathogen, including meronts, sporonts, sporoblasts, and mature spores, are monokaryotic. The sporehas 6–8 windings of the polar filament. Morphological and ultrastructural characteristics of the lifecycle stages place it within the familyUnikaryonidae. However, the phylogenetic tree constructed on the 16S rRNA gene sequence analysis indicates that the pathogen isclosely related to the Nosema/Vairimorpha clade of microsporidia. Therefore, we have classified the microsporidian of C. aurata in thetentative group Microsporidium in order to avoid creating an unnecessary or incorrect new genus/species.