DNA Barcoding and Renewed Taxonomy of South American Clouded Sulphurs (Lepidoptera: Pieridae: Colias)

The genetic relationships of the clouded sulphurs, Colias Fabricius complex of South America, assessed through a study of the COI mitochondrial part of the DNA genome (‘barcoding’) are reported. Barcoding tests used the Barcoding of Life Database platform over a set comprised of 181 specimens of South-American Colias and four outgroup specimens of two geographically closest Neotropical Colias (C. philodice guatemalena Röber and C. eurytheme eurytheme Boisduval inhabiting southern North America). According to the data obtained, all South-American clouded sulphurs constitute a natural concise group (monophyletic clade), characterized by large interspecific and moderate intraspecific mutational divergences in the mitochondrial part of the genome and peculiar structure of the haplotypes/haplogroups. This clade is largely, and with high bootstrap support, detached from the clade of ‘true’ Colias occurring in Eurasia, North America, and Africa, that stems from a joint analysis over the sequences received for the two groups of Colias butterflies. Hence, the clade encompassing all species of South-American clouded sulphurs requires designating a separate genus, Scalidoneura stat. nov. (gen. rest. per historical priority), which is sister to the clade encompassing all Colias species occurring in the rest of the world, for which the genus name Colias is used. Furthermore, among South-American clouded sulphurs (Scalidoneura) are three phenotypically distinctive species – S. dimera Doubleday and Hewitson, S. vauthierii Guérin-Méneville, and S. alticola Godman and Salvin (with the latter, ex-subspecies of C. euxanthe Felder and Felder, being re-raised to full-species rank: stat. nov., viz. sp. rest.) – which are very divergent genetically. On the contrary, the rest of four South-American Scalidoneura species (quite different in habitus, too) – S. euxanthe, S. lesbia Fabricius, S. misti Kir’yanov, and S. flaveola Blanchard – are almost indistinguishable in their DNA barcodes. In addition, for peculiar species S. alticola, separate on the phylogenetic trees among other South-American clouded sulphurs, it is worthwhile to erect Altocolias subgen. nov. within the genus Scalidoneura. The new systematic approach used in the present study, which is basically grounded on DNA barcoding and revisiting the subgenera concept for worldwide clouded sulphurs, deletes internal inconsistencies and controversies that hindered previous attempts to propose a stable system for this peculiar block of pierid butterflies.