Genus Aclastus Förster, 1869

Aclastus Förster, 1869: 175 . Type: Aclastus rufipes Ashmead, 1902 . Included by Ashmead (1902).

Microplex Förster, 1869: 175 . Type: Aclastus rufipes Ashmead, 1902 . Included by Roman (1909).

Daetora Förster, 1869: 175 . Type: Hemiteles solutus Thomson, 1884 . Designated by Perkins (1962).

Opisthostenus Förster, 1869: 175. Type: Hemiteles (Opisthostenus) etorofuensis Uchida, 1936 . Included by Uchida (1936b).

Fetialis Rossem, 1990: 315 . Type: Fetialis alacris Rossem, 1990 . Original designation.

A single species, Acl. etorofuensis (Uchida, 1936), has been recorded from Japan. In addition, I found at least two undetermined species from Japan. In this study, I re-describe Acl. etorofuensis with some distributional data.

Preliminary key to Japanese species of the genus Aclastus (♀)

1. T III almost entirely smooth (Fig. 38D). Antenna with 18–20 flagellomeres. ........................................ Acl. etorofuensis (Uchida, 1936)

-. T III largely punctate. Antenna with various number of flagellomeres. ............................................................................................ 2

2. Antenna with 19–20 flagellomeres. Ovipositor straight, distinctly shorter than hind tibia. ............................................................................... Acl. sp. A

-. Antenna with 23–24 flagellomeres. Ovipositor entirely upcurved, almost as long as hind tibia. ............................................................................... Acl. sp. B