Tersilochinae (Hymenoptera: Ichneumonidae) of Vietnam, Part 2: genus Barychemis Forster, 1869

Abstract

The genus Barycnemis Forster, 1869 (Hymenoptera: Ichneumonidae: Tersilochinae) is most abundant and species rich in the Holarctic region where about 35 species are known, i.e. 15 species in the Nearctic region and 26 in the Palaearctic region. Beyond the Holarctic region, one species occurs in Central America, two in the Oriental region and one in Australia. Only two species of Barycnemis were recorded from the Oriental region till now: B. dissimilis (Gravenhorst, 1829) from Nepal and B. sanctijohanni (Rao et Kurian, 1951) from North India. Nothing was known about the occurrence of the genus Barycnemis in Vietnam until present day. In this paper, two species of Barycnemis, B. dissimilis and B. liliputana sp. nov., are found to occur in Vietnam. Barycnemis liliputana sp. nov., with body length 1.6 mm and fore wing length 1.4 mm, is the smallest known tersilochine species. The new species may easily be recognized by its extremely small size, very slender antennal flagellum with only 14–16 flagellomeres and highly polished head and mesosoma. It resembles B. gracillima (Thomson, 1889) occurring in Europe, Caucasus and Kazakhstan as both have a similar head and slightly depressed ovipositor, but B. liliputana differs from this species, in addition to the characters listed above, by its slender first metasomal segment with small glymma (similar to those in B. dissimilis and B. tobiasi Khalaim, 2004) and slender legs. Barycnemis dissimilis is also recorded from Taiwan and North India. The genus Barycnemis is recorded from Vietnam and Taiwan for the first time. An identification key to the two Barycnemis species occurring in Vietnam is provided.