Dolichomitus, Smith, 1877

Kopylov, D. S., Spasojevic, T. & Klopfstein, S., 2018, New ichneumonids (Hymenoptera, Ichneumonidae) from the Eocene Tadushi Formation, Russian Far East, Zootaxa 4442 (2), pp. 319-330 : 326

Dolichomitus ? saxeus Kopylov, Spasojevic & Klopfstein sp. nov.

Figure 5

Holotype. PIN, 3364/31, part with counterpart. Imago, sex unknown, mainly dorsal aspect (but see following and description below). Head absent; mesosoma rather well preserved, but with apical part of propodeum and most of T1 obscured by coxae; legs missing excluding hind coxae and one detached femur; antennae and ovipositor missing, fore wings and one hind wing preserved. Ugolny, Russian Far East, Eocene, Tadushi Formation.

Etymology. The species name is derived from the Latin word “saxeus”, which means “rocky” or “made of rock”.

Description. Coloration. Mesosoma, coxae and wing veins very dark, metasoma and legs somewhat lighter, brownish.

Mesosoma. Mesonotum coarsely punctured, as long as wide and 2.7x as long as scutellum. Notauli strong, converging, reach the middle of mesonotum. Propodeum carination unclear, with break between part and counterpart potentially inside the body.

Wings. Fore wing 3.3× as long as wide; pterostigma and cell 3R elongate, both about 3.9× as long as wide; areolet large, 2.3× as long as wide, almost triangular, with 4-M very short (2× as long as vein width), 2+3M 1.6× 2- Rs, 1.6x r-m, petiolus of areolet (3-Rs) 0.24× as long as areolet width; 1-Rs&1-M almost straight; 1m-cu&2-Rs+M gently curved, with no sharp bend or traces of 1-Rs+M; r-rs issues at mid-length of pterostigma, s-shaped, 2.8× pterostigma width. Hind wing with 1-Rs 1.1× as long as r-m; 1-Cu 0.9× as long as cu-a, the two veins meeting at a 120° angle.

Metasoma. Metasoma a little elongate, fusiform, 3.0× as long as wide and 2.1× as long as mesosoma. T1 elongate, 1.7× as long as wide, comprises 0.22 of metasoma length. T1 carinae, if present, not visible on the specimen. T2 and T3 wider than long, but still longer than posterior tergites. T5 is the widest.

Measurements. Mesosoma length 3.3 mm, metasoma length 6.9 mm. Fore wing length 9.9 mm, width 3.0 mm.

Taxonomic placement. The placement of this fossil is not straightforward, given its incompleteness and, in particular, lack of visible ovipositor. The venation of the fore wing, especially the almost triangular areolet receiving vein 2m-cu close to its outer corner, 2m-cu bowed outwards and probably with two bullae, and s-shaped vein r-rs point to the subfamily Pimplinae . The hind wing vein 1-Cu being a bit shorter than cu-a indicates either Ephialtini or Delomeristini (in Pimplini , 1-Cu is invariably much shorter than cu-a, see Fig. 1 ). Several genera in Ephialtini have similarly elongate fore wings with a large triangular areolet; most of them also have elongate metasomal tergites, but with quite some variation. The incompleteness of the fossil does not allow a clear attribution to one of these genera, and we thus place it tentatively in Dolichomitus as its wing venation, size and metasomal tergite lengths fall within the variation found in the extant species of this large genus.

Figures

FIGURE 1. Phylogeny of Pimplinae and outgroups, redrawn according to Gauld et al. (2002), with examples of propodea, first metasomal tergites and hind wings shown to the left of the genus names. The drawings are modified from Townes (1969), and the species representatives are, from top to bottom: Xorides irrigator Fabricius, Odontocolon ochropus Townes, Poemenia hectica Gravenhorst, Rhyssa persuasoria Linnaeus, Theronia atalantae Poda, Lissopimpla excelsa Costa, Xanthopimpla hova Saussure, Echthromorpha agrestoria Swederus, Itoplectis maculator Fabricius, Pimpla madecassa Saussure, Zatypota percontatoria Müller, Dreisbachia mira Tosquinet, Camptotypus pulchripennis Saussure, Scambus tecumseh Viereck, Flavopimpla nava Tosquinet, Delomerista novita Cresson, Atractogaster semisculptus Kriechbaumer, and Perithous albicinctus Gravenhorst.

FIGURE 5. Dolichomitus? saxeus sp. nov. holotype PIN, 3364/31: a—part, b—our interpretation.