3.7 Nemophora sakaii species group

Diagnosis. This species group can be distinguished by the following characters: the forewing is distinctly broad, length about 2.6–2.7 times of width; the transverse central fascia is usually placed at 1/3 of the forewing, light yellow to orange-yellow, both sides with narrow black margins; the half of forewing is not far away central fascia with an inconspicuous black transverse band; the suspensorium is nearly quadrate anteriorly and expanding posteriorly, anterior part is far beyond posterior margin of vinculum in ventral view; and the aedeagus is distinctly curved dorsally with asymmetrical or serrated apical lobes.

Remarks. This species group includes three species, namely N. sakaii (Matsumura, 1931), N. hunanensis sp. nov. and N. purpurata sp. nov., of which the latter two are new species. This species group is similar to the aurifera and diplophragma groups, but it can be easily distinguished by the obviously broad forewing and an inconspicuous black transverse band on the transverse central fasciae of the forewing. In addition, N. sakaii is also similar to the decisella group in the forewing pattern, but it can be characterized by the central fascia of the forewing with narrow black margins on each side, and by the similar forewing pattern in male and female.

Key to species of the sakaii group based on external morphology and male genitalia

1 Male eyes moderate in size, eye size index about 1.2; forewing transverse central fascia obviously narrow............... 2

- Male eyes very large, eye size index more than 6; forewing transverse central fascia obviously broad............. N. sakaii

2 Forewing transverse central fascia wider at middle than margins; valva with relatively pointed apex; suspensorium not beyond posterior margin of vinculum or at the same level............................................ N. purpurata sp. nov.

- Forewing transverse central fascia broadest on costal margin and gradually narrow to posterior margin; valva with truncated apex; suspensorium far beyond posterior margin of vinculum................................. N. hunanensis sp. nov.