Epitheronia stigmatica ( Henriksen, 1922 ) Klopfstein, 2022

Klopfstein, Seraina, 2022, High diversity of pimpline parasitoid wasps (Hymenoptera, Ichneumonidae, Pimplinae) from the lowermost Eocene Fur Formation (Denmark), Geodiversitas 44 (23), pp. 645-664 : 655-656

Epitheronia stigmatica ( Henriksen, 1922) , n. comb.

( Fig. 7 )

Pimpla stigmatica Henriksen, 1922: 18 .

TYPE MATERIAL. — Holotype examined at the Natural History Museum in Copenhagen.

TYPE HORIZON AND LOCALITY. — The type locality is given as “Thy” in original description, probably referring to the traditional Thy district in the Limfjord region in Jutland, Denmark. Additional specimens are from Denmark, Jutland, Limfjord region, Skive Kommune, Stolleklinten (FUR-11922, 12707) , ManhØje, Den nye grav ( FUR-11610 ) ; MorsØ Kommune, Gullerup ( FUR-11110 ) ; and Ejerslev Molergrav , 56°55’5”N, 8°55’6”E ( MOL-MM-3141 ) ; unknown ( FUR-16635 ) .

MATERIAL EXAMINED. — All females:MOL-MM-3141, FUR-10099, 11110, 11610, 11922, 12707, 16635. The following specimens are tentatively placed in this species: FUR-9645, 10100, 11163, 11267, 11342, 13075, 15841.

DIAGNOSIS. —Taxonomic placement: Henriksen correctly identified Pimplinae as the most likely subfamily. The areolet shape, outwardsbowed 2m-cu in the forewing, as well as the short and stout T1 and robust, protruding ovipositor clearly indicate this subfamily. The species was originally placed in Pimpla , but that was nearly fifty years before Henry Townes profoundly revised the generic classification of Darwin wasps ( Townes 1969). While generic placement is ambiguous based on the holotype alone, the additional fossils here-in associated with this species are much better preserved. The yellow or orange ground colour and robust ovipositor point to either Xanthopimpla or to the Theronia group of genera. The in some specimens well-visible mandibles with two teeth exclude the former, which has twisted mandibles that appear unidentate in lateral or front view. Within the Theronia group, only Epitheronia has the lower tooth of the mandible distinctly shorter than the upper tooth.

Species diagnosis:the tri-coloured antenna distinguishes this species from all extant Epitheronia . There are two fossil species currently associated with the Theronia group, both described from the Miocene Florissant formation by Cockerell (1919): Theronia wickhami Cockerell, 1919 and Mesopimpla seqoiarum Cockerell, 1919 . We obtained photographs of the former from the University of Colorado Museum of Natural History, and it belongs to the Cremastinae. The whereabouts of the latter is unknown, but according to the original description, it is mainly black. Furthermore, drawings of the wing veins show that forewing vein 2m-cu is rather straight (bowed outwards in the new species) and that hindwing vein 1-Cu is longer than cu-a (distinctly shorter in E. stigmatica n. comb.).

DESCRIPTION

Preservation

Holotype rather poorly preserved, dorsal view. Head only partial, antennae missing except for some barely visible basal segments. Mesosoma poorly preserved, mesoscutum apparently broken off except for narrow, dark borders; left fore and hind wing well-preserved, traces of about two legs. Metasoma slightly better preserved, most tergites clearly or at least vaguely outlined, dark colouration only indicated in parts as slightly darker brown; ovipositor sheaths and base well preserved.

Best-preserved specimen (MOL-MM-3141) shown in lateral view. Head including two complete antennae, mesosoma without much detail, forewings and a partial hind wing and large parts of all six legs present. Metasoma almost complete; ovipositor sheaths well preserved. Additional specimens either in ventral (FUR-10099), dorsal (FUR-11610) or lateral view (FUR-11110, 11922), in two cases (FUR-10099, 11922) with nearly complete antennae and in two with well-preserved legs showing enlarged claws (FUR-11110, 11922).

Body 9.1-13.2 (9.1) mm. Yellow to light orange, with dark brown compound eyes and maybe head and marks on mesosoma, especially around wing base. Antennae orange on basal third, then with broad white ring, dark brown on apical 0.4. Wing veins dark except for light mark on basal c. 3rd of pterostigma; legs orange, hind tibia apically and hind tarsi darkened (see FUR-11110). Dark markings at base of tergites 1 – at least 5 (see also discussion of colour preservation); ovipositor sheaths dark.

Head. Very short, with large compound eyes; in specimens MOL-MM-3141 and FUR-11922 with bidentate mandibles well visible, lower tooth distinctly shorter and a bit more narrow than upper tooth. Antenna about 1.1 × longer than fore wing, of even width, with about 34 to 39 flagellomeres; scape a little longer than wide, pedicel short, first flagellomere about 3.5 × longer than wide, subsequent ones decreasing in length to nearly quadrate in most apical flagellomeres.

Mesosoma. Rather short and stout; deep notauli converging on basal half, then nearly parallel (FUR-11610); dark patches at fore wing base probably corresponding to axial sclerites; scutellum with transverse carinulae in prescutellar groove; propodeum higher than long, carination somewhat unclear, but seemingly with at least some closed areas and pleural carinae (MOL-MM-3141, FUR-11110).Fore wing 8.0-9.5 (8.0) mm; areolet closed, quadrate, with uneven sides, 4-M very short, 2r-m a bit shorter than 3r-m; 2m-cu curved outwards, with two bullae; pterostigma 3.5-4.2 (4.0) × longer than wide; 1cu-a meeting M + Cu a little posterior to 1-M; 3-Cu much longer than 2cu-a; radial cell 3.3-3.7 (3.3) × longer than wide. Hind wing with 1-Rs about 1.5 × longer than 1rs-m (holotype, FUR-11610), 1-Cu 0.6-0.7 (0.65) × as long as cu-a. Legs rather well preserved, with two spurs at mid and hind tibial apex; hind femur about 2.9-3.6 (3.6) × longer than wide; claws rather large.

Metasoma. Rather stout, T1 about 0.8-1.0 (1.0) × as long as wide, with strong median longitudinal carinae converging on basal half (FUR-11110);T2 0.5-0.7 (0.7) × as long as wide,T6 about the same length as T7,T8 very short. Ovipositor sheaths robust, 0.25-0.3 (0.3) × as long as fore wing; rather broad, covered with very dense and short hairs (MOL-MM-3141).

REMARK

The holotype of Pimpla stigmatica is rather poorly preserved, with the body mostly just outlined in the fossil, without showing any details.To avoid defining unnecessary new names, I here adopt this name for the species with the three-coloured antenna that is found rather commonly in the Fur Formation deposits. The venation of the fore and hind wing of the holotype fits rather well with these specimens, and there are no discernible characters on the body that would contradict the association, even though the holotype is at the lower end of the size spectrum.

Figures

FIG. 7. — Specimens of Epitheronia stigmatica (Henriksen,1922), n. comb.: A, C, holotype,deposited at the Natural History Museum in Copenhagen;B, D, specimen MOL-MM-3141.Photographs (A, B), detail (E) and interpretative drawings (B, D), where dotted lines represent uncertain and/or interpolated interpretations. Scale bars: 2 mm.