Phytophagy in a Polypedilum (Diptera: Chironomidae) species new to Australia and Japan: taxonomy and expanded Asian distribution

Abstract

Polypedilum johannseni Sublette & Sublette (= Chironomus (Polypedilum) anticus Johannsen), described from Indonesia, is recorded from Australia, where larvae are newly reported to feed on species of the aquatic fern Azolla Lam. (Salviniaceae). We extend the Australian distribution for the species that was reported previously as Polypedilum ‘nr seorsus’ from northern Australia. Review of the species in Asia shows previously known presence in Singapore as Polypedilum anticus and in Thailand and the Philippines, where the larva was reported to feed on Azolla. In China, Polypedilum johannseni is reported from a diverse range of aquatic host plants, including Azolla. We also newly report the species from Japan, where larvae feed on hybrid Azolla cristata × Azolla filiculoides and Trapa japonica Flerow (Lythraceae). We review the taxonomy, provide new illustrations, record and map the wider distribution and comment on morphological variation. Here, we also redescribe the Australian Polypedilum seorsus (Skuse) with which P. johannseni has been confused, and from China, we redescribe Polypedilum tigrinum Hashimoto, the larva of which is a proven aquatic phytophage that co-occurs with several species of Polypedilum, including P. johannseni.