Exochorionic morphology in two species of white Eurema (Pieridae: Coliadinae) and its taxonomic contrast on Euremina proposals

We described and illustrated the exochorion of six subspecific taxa in two species of Eurema (sensu lato) with white phenotype— E. agave and E. albula —with the staining and scanning electron microscopy (SEM) techniques. We also performed a tabular comparison of our results. We re-examined the description of E. albula ceciliana and inspected its exochorion with SEM.

We made SEM photographs in five regions of the chorions of the six subspecies: micropylar, perimicropylar, apical, equatorial, and basal. Their exochorionic characters are considered plesiomorphic among those recorded in another Coliadinae and similar of those in Dismorphiinae (considered an older group), with E. agave closest to E. daira, E. elathea, and E. flavescens due to its multiple polygonal grid and lack of micro-grid.

All subspecies of E. albula show a predominantly irregular rectangular macro-grid with a micro-grid. Ribs and micro-grid ribs exhibit similar thicknesses, so it is difficult to differentiate using only the staining technique (except in E. a. albula). The chorionic characteristics of E. albula are plesiomorphic compared to those recorded for other Eurema species with yellow phenotype and closer to those recorded for Leucidia brephos.