Tenuicornus dominicus, Blaeser, Marcel, Krogmann, Lars & Peters, Ralph S., 2015

Blaeser, Marcel, Krogmann, Lars & Peters, Ralph S., 2015, Two new fossil genera and species of Cerocephalinae (Hymenoptera, Chalcidoidea, Pteromalidae), including the first record from the Eocene, ZooKeys 545, pp. 89-100 : 95-96

Taxon classification Animalia Hymenoptera Pteromalidae

Tenuicornus dominicus sp. n.

Diagnosis.

See genus.

Description.

Female: total body length 2.07 mm; length of mesosoma 0.92 mm, of metasoma 1.02 mm. Body without metallic luster. Head: height 0.39 mm, width 0.38 mm. Face deeply impressed. Shape of head cuboid; mandibles not visible, hidden in facial depression. Margin of facial depression with rough surface and with a thickened seta on each side (length of setae 85 µm). Inner antennal process (iap) positioned distinctly above level of toruli; nail-like, 0.11 mm long, with basis wider than apex, orientated anteroventrally. Eyes large and egg-shaped, 0.25 mm high and 0.2 mm wide. Antennae: inserted at ventral margin of eyes; scape long and slightly curved, length 0.25 mm; pedicel length 75 µm, rather short and stout; funicle 6-segmented with first two funicular segments longer than wide (F1: length: 71 µm × width: 52 µm; F2: 68 µm × 60 µm) and F3-F6 wider than long, distinctly broadening distally, club-like (F3: 59 µm × 72 µm; F4: 60 µm × 74 µm; F5: 58 µm × 80 µm; F6: 52 µm × 86 µm). Clava egg-shaped: 97 µm long and 77 µm wide. Wings: fore wing long and slender (length 1.53 mm and width 0.55 mm); submarginal vein 0.57 mm long, marginal vein 0.38 mm long, postmarginal vein 0.11 mm long, stigmal vein 99 µm long; stigma slightly thickened and uncus visible. Wing disc bare, setal bases absent. Elongate admarginal setae present. Hind wing length 1.27 mm and width 0.27 mm, three hamuli present. Mesosoma: pronotum and anterior part of mesoscutum with slight traces of strigulate surface sculpture; mesonotum otherwise polished. Notauli foveolate. Length of pronotum 0.37 mm, length of mesoscutum 0.22 mm, length of mesoscutellum 0.22 mm; no frenal line. Axillae medially connected. Mesopleuron (in lateral view) height 0.29 mm, width 0.36 mm. Prepectus enlarged and triangular in shape (0.14 mm × 0.17 mm). Length of metanotum 39 µm; length of propodeum 72 µm. Propodeum without a median carina or plicae. Legs: coxae strong and stout. Femora and tibiae long and slender (Fe1: 0.45 mm; Fe2: 0.32 mm; Fe3: 0.41 mm; Ti1: 0.39 mm; Ti2: 0.49 mm; Ti3: 0.42 mm). Metasoma: petiole (Mt1) short and transverse, hardly visible. Metasomal tergites Mt2 to Mt9 smooth, Mt2: 0.28 mm, Mt3: 0.17 mm, Mt4: 0.15 mm, Mt5: 0.16 mm, Mt6: 0.11 mm, Mt7 60 µm, Mt8/9: 71 µm. Ovipositor 0.23 mm (top view) exerted beyond end of gaster.

Taxonomic remarks.

The two genera that are most similar to Tenuicornus are Neocalosoter and Cerocephala . Tenuicornus runs to Neocalosoter in the key of Krogmann (2013) but differs from this genus in various features: Tenuicornus possesses a head that is deeply impressed (convex in Neocalosoter ), the dark transverse bands on its fore wing are absent, and the propodeum has no traces of a median carina or plicae (Fig. 2B). The tentative similarity between Tenuicornus and Cerocephala is based on the deeply impressed face. However, Tenuicornus differs from Cerocephala by the absence of a tuft of setae on the parastigma on the fore wings (Fig. 2E), one of the most distinct characters for the generic classification of Cerocephalinae . Tenuicornus further differs from Cerocephala by the shape and position of the inner antennal process. In Tenuicornus , the process is shaped like a nail and positioned above the level of the toruli at the upper margin of the facial depression (Fig. 2C). In Cerocephala , the process is broader and stouter and positioned at or slightly below the level of the toruli. Furthermore, Cerocephala is described to have all funicular segments longer than wide ( Westwood 1832), while in Tenuicornus only the first two funicular segments are longer than wide. The funicular segments three to six are wider than long (Fig. 2D).

Etymology.

The name dominicus is derived from the amber deposit in which the fossil was found.