Genus Aritranis Förster, 1869

Aritranis Förster, 1869: 187 . Type species: Cryptus exploratory Schulz, 1906 . Designated by Viereck (1914).

Pycnocryptus Thomson, 1873: 471, 500. Type species: Ichneumon peregrinator Linnaeus, 1758 sensu Gravenhorst, 1829 = Ichneumon director Thunberg, 1822 . Monobasic.

Cylindrocryptus Ceballos, 1921: 50 . Type species: Cylindrocryptus nitidus Ceballos, 1921 . Original designation.

Townes (1970) treated both Aritranis (including Hoplocryptus Thomson, 1873) and Pycnocryptus as valid genera. Then Schwarz & Shaw (1998) reviewed these genera and they treated that Hoplocryptus is a valid genus and that Pycnocryptus is a synonym of Aritranis . Aritranis is morphologically similar to Hoplocryptus, but it can be distinguished from the latter by the following character states: dorso-lateral carina of T I absent or indistinct based of spiracle (distinct based of spiracle in Hoplocryptus), postpetiole rather distinctly convex dorsally in lateral view (rather weakly convex in Hoplocryptus) and apical margin of clypeus without a tooth except for A. nigripes group sense Schwarz (with a more or less distinct tooth or a pair of teeth in Hoplocryptus).

In Japan, six species of Aritranis s. lat. had been described by Uchida (1936, 1952, 1956) and Momoi (1963, 1968, 1973) while all of them were transferred from this genus to Hoplocryptus Thomson, 1873 (Yu et al., 2016). Schwarz (2005) recorded a single species, Ar. occisor (Gravenhorst, 1829) from Japan. In this study, I describe a new species from Japan below.