Armadilleon petrorum (Brues, 1910) Spasojevic & Broad & Klopfstein, 2022

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

Armadilleon petrorum (Brues, 1910) comb. nov.

Fig. 10

* Polysphincta petrorum Brues, 1910

Material.

Photographs of the holotype (part, #PALE-2136) obtained from the MCZ.

Stratum.

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

Description.

Female. Holotype in lateral view with nearly complete antennae, partial head, mesosoma detailing sculpture, both fore and hind wings, at least parts of all legs, and metasoma with ovipositor with sheaths. Body length 9.2 mm.

Mostly black, antennae and wing venation dark brown, T2 and following with broad, reddish apical bands, legs orange to dark brown.

Head very short, eyes of normal dimensions. Antennae 6.6 mm, with at least 24 (probably about 32) flagellomeres, basal segments elongate, apical segments transverse. Mesosoma with strong sculpture; pronotum with epomia strong and with numerous longitudinal wrinkles especially along hind margin which continue on mesopleuron; epicnemial carina complete to about mid-height of pronotum; sternaulus long and strong, with transverse carinulae; sculpture of mesopleuron dominated by longitudinal carinulae on much of its surface. Metanotum rather short and high, with some carinulae visible on lower part. Propodeum with pleural carina, indications of lateral and lateromedian longitudinal carinae, anterior transverse and at least lateral portions of posterior transverse carinae, with rugulo-punctate sculpture between the carinae. Wings evenly and densely hairy; fore wing 5.8 mm, with pentagonal areolet; 2m-cu probably with a single bulla; 1cu-a meeting M + Cu opposite of 1M; cell 2R1 3.0 × longer than wide. Hind wing with 1Rs longer than rs-m and 1Cu longer than Cu-a; M + Cu probably strongly curved in apical half. Legs somewhat hard to tease apart, but of rather average dimensions; hind femur 4.5 × longer than wide. Metasom a seems somewhat compressed towards apex; T1 clearly elongate and petiolate, with strong lateral and dorsolateral carinae, remaining tergites transverse; sternites rather strongly sclerotized; hypopygium short and inconspicuous. Ovipositor 2.2 mm, 0.4 × as long as metasoma, straight and parallel-sided, its ventral valve with indications of oblique ridges close to apex, without dorsal subapical notch.

Interpretation.

The conspicuous sculpture visible on the propleuron, mesoscutum, mesopleuron and propodeum, together with the subfamily characteristics (strong sternaulus, petiolate T1 and pentagonal areolet), firmly place this species in the new genus Armadilleon . Additional similar features between the current and the type species of the genus, A. morticinus , include the short head, carination of propodeum, and ovipositor length and shape. The two species differ by the shape of the antennae, which are much stouter in A. morticinus , the different colouration of the metasomal tergites, and fore wing vein 1cu-a meeting M + Cu somewhat distally of 1M in the type species and opposite of 1M in A. petrorum .

Pimplinae Wesmael, 1845

Lithoserix Brown, 1986

Figures

Figure 10. Armadilleon petrorum (Brues, 1910) comb. nov. A. Photograph of the holotype obtained from the MCZ; B. Our interpretative drawing of the fossil. Thicker black lines indicate outlines of body structures, thinner lines show characters inside these outlines, and dotted lines represent uncertain interpretations. Grey lines and circles show conspicuous sculpture of the cuticle.