Leptopilina Förster, 1869

Vogel, Jonathan, Martin, Jakob, Forshage, Mattias, Salden, Tobias, Staverløkk, Arnstein, Verheyde, Fons, Nordlander, Göran, Herz, Annette & Peters, Ralph S., 2025, The Leptopilina Förster, 1869 of the Western Palearctic, and an updated list of the world species (Hymenoptera, Figitidae, Eucoilinae), Journal of Hymenoptera Research 98, pp. 915-969 : 915-969

Genus Leptopilina Förster, 1869

Type species.

Leptopilina longipes (Hartig, 1841) .

Diagnosis.

Leptopilina species are recognized from other cynipoid wasps by having a mesoscutellar plate (as do all members of the Eucoilinae subfamily), the dorsally broadly interrupted to almost absent hairy ring of the metasoma (dorsally shortly interrupted, absent, or complete in other eucoiline genera) in combination with the postpetiolar rim (absent in most genera, e. g. Ganaspis Förster, 1869 and Hexacola Förster, 1869 , present in Cothonaspis Hartig, 1840 , Diglyphosematini, and Zaeucoilini; these usually lack a hairy ring). Female specimens have 13 antennomeres, while male specimens have 15. In males, the second flagellomere (F 2) is curved and somewhat irregular (unlike in several other groups of Eucoilinae , where the first flagellomere (F 1) is irregular).

Leptopilina species can have their hairy ring reduced and species of Diglyphosematini, Zaeucoilini or Cothonaspis can developed an unusually distinct hairy ring. In these cases, Leptopilina can be differentiated from the Diglyphosematini and Zaeucoilini by having a regularly wide pronotum without distinct shoulders (very broad pronotum with distinct shoulders in Diglyphosematini and Zaeucoilini). Additionally, the male F 1 is modified in Diglyphosematini and Zaeucoilini and the metasoma is roundish, not longer than high in Diglyphosematini and Zaeucoilini (more elongate in Leptopilina ). In comparison to Cothonaspis , Leptopilina species have a much less elongate appearance, especially the mesosoma is less elongate in Leptopilina , with a mesoscutum about as long as wide (clearly longer than wide in Cothonaspis ), and the propodeal area is much more setose in Leptopilina (hardly any seta in Cothonaspis ).

Remarks.

A more extensive diagnosis can be found in Lue et al. (2016).

The name Leptopilina was not frequently used after its original description by Förster (1869). Kieffer, who was generally circumscribing taxa by a minimal set of a priori chosen diagnostic characters and did not study types, collected a somewhat haphazard assembly of species under the name Leptopilina in his Cynipoidea world monograph ( von Dalla-Torre and Kieffer 1910). His concept of the genus was of limited use, so that for 70 years, only a single species was described in it. Later, Nordlander revisited eucoiline classification based on type studies and phylogenetic concerns. His type studies showed that some of the species, which had been described by 19 th century authors and that he could not immediately associate with a genus name, were not currently classified in a meaningful way. The genus name Leptopilina was not in use by these authors, despite being available since Förster (1869). And it turned out that two slightly better known yet misclassified species belonged there ( L. heterotoma and L. boulardi , then known as Pseudeucoila bochei Weld, 1944 and Cothonaspis boulardi Barbotin, Carton & Kelner-Pillault, 1979 respectively). Thus, it is from Nordlander’s revival of the genus (1980) that the modern sense and use of the name originates.

Leptopilina is currently classified as belonging to the tribe Eucoilini together with the type genus Eucoila Westwood, 1833 , the genera Afrodontaspis Weld, 1962 , Bothrochacis Cameron, 1904 , Linaspis Lin, 1988 , Linoeucoila Lin, 1988 , Maacynips Yoshimoto, 1963 , Quasimodoana Forshage, Nordlander & Ronquist, 2008 , and the far more common Trybliographa Förster, 1869 ( Buffington et al. 2020). The Eucoilini as currently defined seemed monophyletic only in the analyses of Fontal-Cazalla et al. (2002) (morphological characters) and Forshage et al. (2008) (European taxa only, morphological characters), while already the first combined analysis using molecular and morphological data ( Buffington et al. 2007) resulted in a more problematic topology with the Eucoilini as a paraphyletic grade leading up to Trichoplastini, and some other genera complicating the picture further. An additional difficulty is that some of these genera are much more poorly known than Leptopilina and not necessarily well circumscribed (such as Maacynips and Leptolamina Yoshimoto, 1962 ). Recent analyses ( Blaimer et al. 2020; Guinet et al. 2025, and unpublished results) have retained a problematic picture with a non-monophyletic Eucoilini , but the taxon sampling has not been broad enough and the results not stable enough to suggest a new improved classification with monophyletic and recognisable tribes, so this task remains to be undertaken.

Leptopilina novicia Belizin, 1964 was described from Armenia so it is a Western Palearctic species, but it does not belong in Leptopilina and is here formally moved to Hexacola resulting in the comb. nov. Hexacola novicia (Belizin, 1964) , as was suggested in the now offline Fauna Europaea database ( Ronquist and Forshage 2004). The type is held at ZIN and was studied by GN and MF.

Body size varies greatly within species in Leptopilina (as is common in parasitoids), and is something like 1.0– 2.2 mm across the genus (not considering occasional rare aberrant specimens that are even smaller or larger). For those species of which we have studied numerous specimens, the average body size falls in either the higher or lower part of this range. Deviations from the average usually peak around the opposite end with a more or less distinct gap between the average and the deviant group of specimens. For this reason, we give body size mainly in relative terms in the species diagnoses of these species.