Integrative characterisation of the Northwestern European species of Anacharis Dalman, 1823 (Hymenoptera, Cynipoidea, Figitidae) with the description of three new species

The genus Anacharis Dalman, 1823 comprises parasitoid wasps that target early instars of brown lacewing larvae (Neuroptera: Hemerobiidae). So far, five species were recognised from the Western Palaearctic region, of which four are reported from Northwestern Europe. In this study, we address the Northwestern European species diversity of the genus with an extended integrative taxonomy toolkit. A total of 700 specimens were examined for their external morphology, including the relevant type specimens. For 354 specimens, we obtained CO1 barcode sequences and applied three molecular species delimitation methods. All DNA barcode data are made publicly available via the German Barcode of Life (GBOL) and Barcode of Life Data system (BOLD) database. In addition, we examined images of Wing Interference Patterns (WIPs), examined the male genitalia and performed multivariate morphometric analyses. The analyses revealed two clusters which we describe as the immunis and eucharioides species groups based on differences in DNA barcode, external morphology, WIPs and size of the male genitalia. Furthermore, we complement the diagnosis of the genus Anacharis and describe three new species, Anacharis martinae Vogel, Forshage & Peters, sp. nov. , Anacharis maxima Vogel, Forshage & Peters, sp. nov . and Anacharis minima Vogel, Forshage & Peters, sp. nov. Finally, we synonymise A. fergussoni Mata-Casanova & Pujade-Villar, 2018, syn. nov. with A. eucharioides (Dalman, 1818), and we reinstate A. ensifer Walker, 1835, stat. rev. , A. typica Walker, 1835, stat. rev. and A. petiolata Zetterstedt, 1838, stat. rev. as valid species. In total, we recognise nine Northwestern European species to which we provide an identification key. The species of Anacharis are morphologically very variable. Morphometric analyses alone did not provide information sufficient to delimit species, neither did analyses of WIPs and male genitalia, with few notable exceptions. Analyses of molecular sequence data proved crucially helpful to reliably delimit species and to find morphological diagnostic characters in a reverse taxonomy approach. For delimiting species groups, all included analyses proved helpful, and we show that exploring an extended integrative taxonomy toolkit can be beneficial for a comprehensive characterisation of species. We acknowledge that a complete overview of species distributions, and characterisation of ecological niches & host records is still required to deeply understand the genus as a whole, yet our results already allow broad access to and inclusion of Anacharis species in downstream biodiversity research.