Distinguishing features of male and female Forest Ringlet (Dodonidia helmsii) butterflies.

Abstract

Almost 130 museum specimens and dorsal photographs of the Forest Ringlet butterfly (Dodonidia helmsii) are examined. Measured variations in butterfly size, abdomen dimensions and wing markings are evaluated to assess which, if any, of these attributes may aid identification of male and female of the species. Abdomen dimensions are found to be the most reliable discriminator, with females having a mean abdomen length: width (L:W) ratio of 3.54+/-0.59, whilst males have a mean L:W ratio of 8.10+/-1.39. There was no overlap between the sexes. Measured wingspans ranged from 39.77-57.56mm and forewing lengths from 22-30mm. Whilst most females are larger, being >47mm wingspan and >25mm forewing length, there is considerable overlap between the sexes, so size alone is considered unreliable for gender recognition, at least for samples across a wide geographic area. Dodonidia helmsii forewing markings show subtle but distinct differences between the sexes based on the extent and connectivity of yellow-orange bands. Used in conjunction with the abdomen L:W ratio, the pattern of forewing markings is considered a highly reliable way of confirming the sex of individuals. This improved confidence in gender recognition will greatly aid our observation and understanding of gender-related behavioural differences and ecological knowledge of the species.