Xorides sejugatus (Brues, 1910)

Spasojevic, Tamara, Broad, Gavin R. & Klopfstein, Seraina, 2022, Revision of 18 ichneumonid fossil species (Hymenoptera, Ichneumonidae) highlights the need for open nomenclature in palaeontology, Fossil Record 25 (1), pp. 187-212 : 187

Xorides sejugatus (Brues, 1910)

Fig. 18

* Xylonomus sejugatus Brues, 1910

Material.

Photographs of the holotype (#PALE-2211) and of two paratypes (#PALE-2212 and #PALE-2213), obtained from the MCZ.

Stratum.

Teller County, Florissant shales, Colorado, USA. Late Eocene (Chadronian), 37.2-33.9 Ma.

Description.

Female. Holotype, paratypes with sex unknown. Holotype in lateral aspect showing head, few basal segments of antennae, rather well-preserved mesosoma, almost complete fore and hind wings, nearly complete legs, metasoma and ovipositor with partial sheaths. Paratypes less well preserved, #2212 showing lateral aspect of partial mesosoma, base of wings, T1-T5 and most of hind legs; #2213 with lateroventral aspect of head, partly discernible antennae, outlined but not well-preserved meso- and basal metasoma, wings and partial legs. Body length 17.25 mm.

Black or dark brown on head and mesosoma and hind coxae, brown wing veins and metasoma, legs lighter brown except for darkened hind femur. Ovipositor dark brown.

Head rather short and high, with long cheek, in #2213 with what looks like two chisel-shaped mandibles. Antennae incomplete, but rather slender and at least 1.3 × as long as fore wing. Mesosoma cylindric, not very elongate, pronotum with epomia strong and reaching mesoscutum; mesoscutum with long notauli, mesopleuron with epicnemial carina reaching pronotum at about mid-height. Propodeum strongly areolated, with lateromedian and lateral longitudinal and pleural carinae, posterior transverse and at least partial anterior transverse carina. Fore wing 11 mm, with areolet open, vein 2Rs almost obliterate; 1cu-a meeting 2Cu slightly distally from 1M; cell 2R1 strongly elongate, 4.2 × as long as wide. Hind wing with 1Cu a little longer than cu-a and 1Rs a little shorter than rs-m. Legs partly preserved, hind femur 3.0 ×, and hind tibia 5.8 × as long as wide. Metasoma depressed, slightly enlarged apically; T1 about 2.3 × as long as wide, slightly expanding apically, with strong ventrolateral, dorsolateral and median dorsal carinae, and with distinct diagonal groves laterally which form part of a constriction around middle of tergite; T2 approximately quadrate, with oblique basal grooves cutting off basolateral corners; T3 a bit wider than long; T4-T6 transverse; T7 slightly longer than T6; S2-S5 visible as brown patches. Ovipositor 9.6 mm, 2.2 × as long as hind tibia, rather narrow.

Interpretation.

Several characters firmly place this fossil in Xorides , including the chisel-like mandibles, long epomia that seems to connect with the dorsal margin of the pronotum, fore wing venation including an open areolet with very short 3rs-m, grooves anteriorly on T2, and lateral diagonal impressions on T1. The only character not usually observed in recent species of the genus are the thickened hind femora.

Ctenopelmatinae Förster, 1869

Parapimpla Theobald, 1937

Figures

Figure 18. Xorides sejugatus (Brues, 1910) comb. nov. A. Photograph of the holotype obtained from the MCZ; B. Our interpretative drawing of the fossil (below). Thicker lines indicate outlines of body structures, thinner lines show characters inside these outlines, and dotted lines represent uncertain interpretations.