Cycad blue butterfly, Theclinesthes onycha, is actually represented by two sub-species that are very similar in appearance. Sub-species capricornia occurs along coastal Queensland from Cape York to about Mackay and Rockhampton. Sub-species onycha occurs from about Rockhampton to as far south as Mt Dromedary, near the NSW-Victoria border. The onycha sub-species occurs along the coast and inland regions, as far west as Carnarvon in Queensland, and Coonabarabran in NSW. Their biology is quite similar, but differences are highlighted in each relevant section below.
Cycad blue butterfly is virtually indistinguishable from wattle blue butterfly (T. miskini), which feeds on many Acacia species, some Corymbia spp., Eucalyptus spp., Atalaya spp. (Sapindaceae), Sesbania spp. and some other species from Fabaceae. In fact, these two species often cannot be identified unless host plant information is available. Overseas, cycad blue butterfly can refer to different species. For example, Chilades pandava in Guam and Asia shares a common name, is closely related and appears very similar to Australian species.