Taxonomic relationship between Earias roseifera Butler and Earias roseoviridis Sugi (Lepidoptera: Nolidae: Eariadinae) with reference to their distributions mainly in Japan

Abstract

Earias roseoviridis Sugi, 1982 is sometimes considered a synonym of E. roseifera Butler, 1881 or possibly a subspecies of E. roseifera because these taxa are morphologically very similar while their taxonomic relationship is unclear. Therefore, we performed molecular and morphological studies to clarify their taxonomic relationship. We found that E. roseifera and E. roseoviridis are distinguishable by standard DNA barcoding of mtCOI and a 1.8% average sequence difference is recognized between them. By the DNA barcoding, we also noticed for the first time that their distributions overlap in the Tokara Island group, Japan and this suggests that they are not different subspecies of the same species. We consider them as two distinct species for the moment based on the following three facts. 1: Such a relatively low percentage of pairwise distance of the DNA barcoding is often observable in Noctuidae. 2: Both taxa are clearly distinguishable by their larval morphology. 3: By the detailed observation of the adults, we established that they could be separated by the coloration of the antennae and of the scales near the eyes on the clypeus. As it is difficult to identify specimens from the Tokara Island group, Japan by morphology only, hybridization may happen between them in the contact area of the two taxa. Further molecular research based on nuclear genes will be necessary to clarify the hybridization.