Two species of Dolichomitus Smith, 1877 (Hymenoptera, Ichneumonidae, Pimplinae) parasitizing borers of Juglans mandshurica Maxim. and a key to species known from China

. Two species of Dolichomitus Smith, 1877 emerged from the trunks of Juglans mandshurica Maxim. in Kuandian and Benxi Manzu Autonomous Counties, Liaoning, in the Palaearctic part of China. One new species, D . juglanse Sheng & Li sp. nov., reared from Menesia ﬂ avotecta Heyden, 1886 and Mesosa myops (Dalman, 1817) (Cerambycidae), is described and illustrated. A key to the species of Dolichomitus known from China is provided.


Introduction
In this paper, two species parasitizing borers of the trunks of Juglans mandshurica Maxim. are reported from China. One new species is described and a key to all known Chinese species of Dolichomitus is provided. Morphological terminology is mostly based on Broad et al. (2018). Images were taken using a Leica M205A stereo microscope with LAS Montage MultiFocus. The key to Chinese species of Dolichomitus was modifi ed from Sheng & Sun (2002, 2010 and Sheng et al. (2004). All type specimens are deposited in the Insect Museum of CBDPC.  (Fig. 7) almost as long as maximum width, slightly expanded medially. Tergite 2 (Fig. 8) 0.9 × as long as posterior width. Mesosternum (Fig. 1) (Fig. 13) distinctly longer than maximum width, median portion not expanded. Tergite 2 (Fig. 14)  Diagnosis Gena (Fig. 3), vertex (Fig. 4) and frons shiny. Median portion of vertex behind stemmaticum with correspondingly dense punctures. Malar space about 0.3 × as long as basal mandibular width. Postocellar line approximately 0.8 × as long as ocular-ocellar line. Flagellomeres elongate. Mesopleuron (Fig. 6) with large posteromedian smooth shiny area. Fore femur weakly compressed, 4.0 × as long as maximum width; outer profi le of middle tibia with sparse short tooth-like setae. Areolet pentagonal (Fig. 10). Propodeum (Fig. 7) in dorsal view slightly expanded medially; anterior 0.3 of lateromedian longitudinal carinae present. Second tergite 0.85 × as long as fi rst tergite. Lower portions of anterior 2 ridges of lower valve of ovipositor ( Fig. 9) distinctly reclivous, posterior 2 slightly inclivous or subvertical. Mesosternum yellow brown or black.

Etymology
The specifi c epithet is derived from the host's food plant.

Host
Unknown. The specimens were collected on a large branch of Juglans mandshurica Maxim., where females of this species were laying eggs into the branch.

Discussion
The type specimens of Dolichomitus juglanse Sheng & Li sp. nov. reared from Menesia fl avotecta (Cerambycidae) in trunks of Juglans mandshurica, in Kuandian Manzu Autonomous County, have the mesosternum brownish yellow, while the specimens from Mesosa myops in J. mandshurica, in Benxi Manzu Autonomous County, have the mesosternum black. We conclude that all the specimens belong to the same species, Dolichomitus juglanse, because all specimens agree almost entirely in all characteristics except for mesosternum color.
The host, Menesia fl avotecta, is largely yellow, while another host species, Mesosa myops, is largely dark. We conclude that the mesosternum with brownish yellow might be because of its host with brownish yellow colouration. This matter would be studied in the future.