Key to Japanese species of Dactylolabis

1. Wing without dark markings except for indistinctly dark stigma (Fig. 4C); hypopygium with outer gonostylus stout and bacilliform, inner gonostylus strongly curved near middle (Fig. 4H).................................. D. longicauda

- Wing with distinct dark areas except for stigma (Figs 1B, 3B); outer gonostylus slender, finger-shaped, inner gonostylus weakly curved near tip (Figs 1G, 3G)............................................................................ 2

2. Prescutum and presutural scutum with four dark stripes; femora and tibiae dark brown except yellow femoral bases; gonocoxite 2.2 times as long as wide or more, basal and apical part almost same in width (Fig. 3F); interbase with middle part broadened into squarish plate (Fig. 3H).............................................................. D. kyororo sp. nov.

- Prescutum and presutural scutum with one or two indistinctly dark stripes; femora and tibiae dark brown distally, gradually turning into yellow toward each base or each tip narrowly dark; gonocoxite 1.7 times as long as wide or less, apparently widest on basal part (Fig. 1F); interbase with middle part narrow, without squarish plate on middle part (Fig. 1H)......... D. diluta