Dimophora? longicornis (Theobald, 1937) 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

Dimophora? longicornis (Theobald, 1937) comb. nov.

Fig. 3

* Nemeritis longicornis Theobald,1937

Material.

Holotype (part only, MNHN.F. B24398 ) examined at MNHN.F.

Stratum.

Aix-en-Provence, Bouche-du-Rhône, France. Late Oligocene (Chattian), 28.4-23.0 Ma.

Description.

Female. Lateral aspect of head, most of both antennae, mesosoma, both fore wings, part of fore and hind legs, and metasoma including ovipositor with sheaths preserved. Body length ~5.3 mm.

Mostly black in colour, with some reddish colouration on metasoma and dark brown to orange-brown legs, wing veins brown.

Head rather short, with eyes not clearly outlined but might be rather prominent. Antennae with scape and pedicel short, with at least 24 flagellomeres, but tips broken. Mesosoma not well preserved; mesoscutum conspicuously elongate, notauli probably present, as is epicnemial carina and probably posterior transverse carina of mesosternum; propodeum evenly rounded, carination unclear given bad preservation. Fore wings 3.1 mm, well preserved; pterostigma broad triangular (3.1 ×) with light base; areolet closed, quadrate and a bit oblique; cell 2R1 (radial cell) short (2.5 ×), ending rather distant from tip of the wing; 2m-cu quite short, forming inner angle greater than 90° with 4Cu, with a single broad bulla; 1cu-a meeting M + Cu opposite of 1M & 1Rs; 3Cu shorter than 2cu-a; vein 1M & 1RS a bit bowed; r-rs shorter than 2Cu. Legs partially preserved; fore coxa, trochanters, base of femur preserved, dark brown; mid leg weakly indicated; hind legs both partially preserved, including elongate hind coxa; hind femur apparently toothless, dimensions unclear, dark brown or orange (the latter colouration might come from overlaying sternites instead); hind tibia very long and slender (10 ×), brown on anterior, orange on posterior half, potentially showing a deep emargination at apex indicative of spurs present in membranous area separate from tarsus (unique character for Cremastinae , but interpretation in fossil not unequivocal); tarsi elongate, one partial claw might show pecten, but interpretation rather uncertain. Metasoma compressed from T3 or T4, mostly black, with reddish colouration on laterotergite 2 and partly on T3 and T4; T1 petiole-shaped, narrow and long (4.7 ×), probably with glymma, spiracle slightly behind middle; T2 as long as T1, laterotergite might be indicated by red colouration; T3 and following shorter, T7 quite long, not distinctly shorter than T6. Ovipositor preserved with sheaths, very long, 4.4 mm, about 3.3 × as long as hind tibia, a bit bowed downwards towards tip.

Interpretation.

The reason that we have covered this species, which was originally described in the genus Nemeritis ( Campopleginae ), is a remark by Theobald in the original description (Theobald 1937) that this species could be identical with Pimpla renevieri Meunier, 1903, which was later repeated by Menier et al. (2004) when he compiled a list of fossil ichneumonids. Based on this list, Yu and Horstmann ( Yu et al. 2012, 2016) catalogued N. longicornis as a Nemeritis synonym of P. renevieri . We could not cover the latter species because the type could not be located. But we studied the former and concluded that several characters support a placement in the subfamily Cremastinae : the narrow T1 in the shape of a petiole, compressed metasoma, fore wing with a short and wide pterostigma and cell 2R1, 3Cu shorter than 2cu-a, hind tibia very long and slender, ovipositor much longer than metasoma. The first set of characters are also present in Campopleginae , but the broad pterostigma and, to a lesser extent, very long ovipositor point to Cremastinae . Given the large and only slightly oblique areolet, the fossil might belong to the genus Dimophora , but crucial characters for generic placement such as the thyridiae are unfortunately not visible. The affinity of the fossil with Dimophora was also supported in the recent total-evidence dating analysis (see supplementary file S12 in Spasojevic et al. 2021), which however included only limited sampling of Cremastinae and Campopleginae . We therefore remove it from synonymy with P. renevieri and tentatively place it in the genus Dimophora .

Cremastinae Förster, 1869

Dimophora ? Förster, 1869

Figures

Figure 3. Dimophora? longicornis (Theobald, 1937) comb. nov. A. Photograph obtained from MNHN. F; B. Our interpretative drawing of the fossil. Thicker lines indicate outlines of body structures, thinner lines show characters inside these outlines, and dotted lines represent uncertain interpretations.