Immature stages of the butterfly Erina gilesi (M.R. Williams & Bollam, 2001) (Lepidoptera: Lycaenidae): description and comparative morphology of Erina species

Abstract

The lycaenid butterfly Erina gilesi (Williams & Bollam, 2001) is endemic to southwestern Western Australia where it is a host specialist of the vine Cassytha racemosa (Lauraceae). We describe, illustrate and compare the immature stages of E. gilesi from two sites south of Perth with other members of the genus. We also illustrate and document variation in larval colour pattern in E. erina (Fabricius, 1775) and E. delospila (Waterhouse, 1903) for the first time. The immature stages of E. gilesi are most similar to its sister species, E. hyacinthina (Semper, 1879), but the late instar larvae differ in having a pair of conspicuous white dorsolateral lines on the body, and the reddish dorsal patches on abdominal segments 1 and 6, which when present, are simple and not raised into projections. The biology of E. gilesi indicates that adults are seasonal and partially bivoltine, with a facultative pupal diapause. A review of larval food plant-butterfly associations indicates that each species of Erina Swainson, 1833 tend to specialise on different species of Cassytha, and generally only one or two plant species are utilised throughout the geographical range of each species/ subspecies, suggesting ecological differentiation in the genus.