3.9 Nemophora rubrofascia species group

Diagnosis. This species group can be characterized by the following features: the compound eyes are very large in male, almost joining to each other; the basal part of the antenna is smooth in both sexes, without raised scales, at most present in the partial medial flagellum of female; the forewing has uniform metallic ground color, usually green, orange, or blue, with bright metallic luster; the forewing central fascia is very large and broad, margined with a silvery-leaden band which is narrowly boarded with black; the female and male adults are the same on the forewing pattern, without sexual dimorphism; and the terminal part of the phallus has a petal-like lamellate process.

Remarks. This species group consists of three species, namely N.rubrofasia (Christoph, 1882), N. chrysoprasias (Meyrick, 1907), and a new species N. caerulea sp. nov. This species group is very similar to the members of the decisella group because they both have bright colors and lusters on the forewing and thorax. Hirowatari et al. (2022) reported N. chrysoprasias from China and found that N. chrysoprasias is more closely related to N. rubrofascia but not N. paradisea and N. smaragdaspis based on morphological and molecular evidence. Apart from these characters, including antenna, male and female genitalia, and the absence of sexual dimorphism in the forewing pattern (Hirowatari et al. 2022), we also noticed an additional difference between these two groups in forewing pattern. Black-margined silvery-leaden bands on each side of the forewing central fascia are nonparallel and asymmetrical to each other, but parallel and symmetrical in the decisella group. In addition, the inside black lines near the forewing base only present anterior half, not extending to the posterior margin, but complete in that of the decisella group. Based on the above evidence, we established a new species group to accommodate these unusual species.

Key to species of the rubrofascia group based on external morphology

1 Forewing ground color mainly blue with metallic luster........................................ N. caerulea sp. nov.

- Forewing ground color not blue.......................................................................... 2

2 Forewing ground color metallic green, scattered with numerous black scales; hindwing entirely white and semitransparent except black apex......................................................................... N. chrysoprasias

- Forewing ground color metallic brass wholely; hindwing uniformly light brown, not semitransparent......... N. rubrofascia