Taxonomic revision of the Euploea alcathoe complex (Lepidoptera: Nymphalidae) from Australia and New Guinea

Abstract

Euploea alcathoe (Godart, [1819]) (Danainae: Danaini) comprises a taxonomic complex, with recent authors recognising one or two species and numerous subspecies throughout its relatively small geographical range. We determined the taxonomic status of populations from northern Australia by integrating data from ecology, larval colour pattern and morphology, adult morphology (wing morphometrics, wing pattern elements and male genitalia) and molecules (mtDNA). We also investigated the broad distribution of phenotypes based on wing pattern maculation throughout mainland New Guinea and its adjacent islands. Available evidence indicates that Euploea eichhorni Staudinger, 1884, stat. rev. from northern Queensland is allopatric and phenotypically and genotypically distinct from E. alcathoe, with 11 phenotypic character state differences in larval pattern and morphology, adult wing pattern and male genitalia, as well as significant differences in wing shape and in frequency distribution of the number of white spots. Genetic data and divergence time estimates based on COI revealed that E. eichhorni and E. alcathoe are reciprocally monophyletic with a mean pairwise divergence of 0.9% and with E. eichhorni comprising only a single unique haplotype. Phylogeographic analysis suggests E. eichhorni diverged as a peripheral isolate from E. alcathoe, most likely during the Late Pleistocene. In the Wet Tropics of northern Queensland, larvae of E. eichhorni specialise on the vine Gymnanthera oblonga (Burm.f.) P.S. Green (Apocynaceae) growing in coastal, broadleaf paperbark swampland, a larval host plant also used by E. alcathoe. A lectotype male of E. eichhorni is designated, with Cooktown, Queensland as the type locality. Euploea alcathoe enastri Fenner, 1991, from the Northern Territory is maintained because it was found to be allopatric, phenotypically distinct, with at least one diagnosable character state (larger number of forewing subapical spots among males), and genetically divergent according to population genetic structure compared with Euploea alcathoe misenus from Torres Strait. Based on our review of E. alcathoe from New Guinea and Torres Strait, we found that populations from at least the southern coastline of New Guinea differed little phenotypically from E. alcathoe misenus; thus, we regard the subspecies Euploea aethiops monaeses Fruhstorfer, 1910, syn. nov. and E. alecto rothschildiana Hulstaert, 1923, syn. nov. as junior synonyms of E. alcathoe misenus Miskin, 1890.