Crusopimpla collina, 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 : 650-651

Crusopimpla collina n. sp.

( Fig. 2 )

urn:lsid:zoobank.org:act:61597B9C-FC57-47DA-9896-A78BFD70CBD9

TYPE MATERIAL. — Holotype female: FUR-14680 (part and counterpart; leg. H. Breiner).

ETYMOLOGY. — This fossil is unusual in its three-dimensional preservation, which allows distinguishing not only the structure of the mesosoma in great detail, but also reveals paired bulges present on T3-T5. It owes its name to these little hills on the metasoma.

TYPE HORIZON AND LOCALITY. — Denmark, Jutland, Limfjord region, Skive kommune , Fur. Cement stone .

DIAGNOSIS. — Taxonomic placement: most of the characters that we use here to diagnose Pimplinae are well visible in this specimen ( Table 1 ), and it in terms of body proportions would fit well among some smaller-sized ephialtine genera such as Scambus Hartig , Gregopimpla Momoi or Iseropus Förster. However , the exceptionally well-preserved propodeum reveals a nearly complete carination, which is not a character that is seen anywhere in the subfamily today. As different tribes and genus groups within Pimplinae feature different carinae being reduced, Kopylov et al. (2018) concluded that a full set of carinae is probably the plesiomorphic state in the subfamily. Based on a fossil from the Eocene Tadushi formation, they described a new genus, Crusopimpla , which shows extensive propodeal carination. The two species currently placed in Crusopimpla ( C. tadushiensis Kopylov, Spasojevic & Klopfstein and C. redivia (Brues)) only have the forewings and not the hindwings preserved, which is why any statement about the relative lengths of veins 1-Cu and cu-a (which together form the nervellus) is missing from the original description of this genus. Our species clearly has the nervellus broken below the middle, with vein 1-Cu about 1.5 × as long as cu-a. It is unclear what the plesiomorphic state of this character might be in the subfamily, but we currently certainly cannot use this character to rule out placement in this genus. We thus place our fossil here and thus expand the generic definition by this character. Also, the genotype C. tadushiensis appears to be dark coloured, although that might be an artefact of preservation, while C. redivia and the specimens added to the genus here show light brown or orange metasomas.

Species diagnosis: Compared to the genotype Crusopimpla tadushiensis , C. collina has more slender tergites (e.g., T2 0.55 × as long as wide, versus 0.32 in C. tadushiensis ). Crusopimpla ? rediviva is preserved only in lateral view, making measuring of tergite proportions difficult. But the latter species has a much more slender pterostigma (4.2 × longer than wide, vs 3 × in the current species). The two species previously in the genus also do not show any convex bulges on the tergites, even though that characters might have been obscured during fossilization.

DESCRIPTION

Preservation

Body in dorsal view. Head probably turned around on the neck, thus showing from below and from the back; antennae missing. Mesosoma rather well preserved, including propodeal carination and details of the scutellar and postscutellar region; fore wings both nearly complete, partial hind wings present; partial legs visible. Metasoma almost complete, including sculptural elements on tergites; ovipositor sheaths well preserved, tip of ovipositor exposed and showing minute details.

Body 9.1 mm. Head and mesosoma dark brown; wing veins brown, pterostigma brown except for narrowly light area at base; legs orange. Metasoma orange, dark brown on T1 and with dark brown patches of various shapes on the remaining tergites (although that might be artefactual); ovipositor orange, its sheaths black.

Head. with orientation somewhat uncertain: clearly showing hind side of head, with distinctive foramen magnum

and genal carina, but might have turned around on its stalk and showing the ventral side.

Mesosoma. rather short and stout; deep notauli converging on basal 1/3, then no longer visible; tegulae indicated by lighter areas; prescutellar groove with deep pits on either side, scutellum rather short, and convex; postscutellum outlined; propodeum with distinct carination, corresponding to nearly complete lateromedian and at least partial lateral longitudinal and pleural carinae and at least partial basal and apical transverse carinae, including complete outline of right area externa and area dentipara; indication of either apophyses or extended hind corners of pleural carinae. Fore wing 7.0 mm; areolet closed, broadquadrate to nearly pentagonal, with uneven sides, 4-M very short, 2r-m a bit shorter than 3r-m; 2m-cu with two bullae, bowed outwards on entire length; 1cu-a meeting M + Cu opposite 1-M; short ramulus present; 3-Cu longer than 2cu-a; radial cell 2.5 × longer than wide. Hind wing with 1-Rs about 1.7 × longer than 1rs-m, 1-Cu probably about 1.5 × as long as cu-a. Mid and hind legs not well preserved, but rather stout.

Metasoma. With T1 about 0.95 × as long as wide, with strong median longitudinal carinae converging on basal half, then slightly diverging and finally converging again; T2 0.55 × as long as wide, with basal oblique grooves cutting of anterolateral corners, seemingly convex in-between, colouration showing roundish patterns which probably indicate strong punctuation; T3-T5 with paired roundish bulges that again show signs of strong punctuation; T7 clearly longer than T6. Ovipositor sheaths 0.22 × as long as fore wing; ovipositor tip extending from sheaths, with teeth-like outline clear at least on right side.

Figures

FIG. 2. — Holotype of Crusopimpla collina n. sp. (FUR-14680), photograph (A), detail (B) and interpretative drawing (C), where dotted lines represent uncertain and/or interpolated interpretations; D, wing vein names on photographs of the extant Darwin wasp Rhimphoctona obscuripes (Holmgren, 1860). Scale bars: A, C, 2 mm; B, 200 µm.