Open Access

Results from a comparative anatomical study of the mesosomal skeleton of Chalcidoidea are presented. External and internal features are described and illustrated for 39 chalcidoid taxa, representing 16 families and 29 subfamilies. This is the most comprehensive morphological study ever conducted for the superfamily. The mesosoma was dissected, macerated and investigated using scanning electron microscopy. The mesothorax and metathorax contributed most of the phylogenetically relevant information. The metafurca is highly variable within Chalcidoidea but seems to be relatively constant at the subfamily level. One hundred and fifty-four morphological characters were scored and analysed cladistically. Outgroup species were chosen from six apocritan superfamilies: Stephanoidea, Ceraphronoidea, Cynipoidea, Platygastroidea, Proctotrupoidea and Mymarommatoidea. Some previously suggested chalcidoid relationships were retrieved: (1) Pteromalidae: Pteromalinae + Miscogasterinae + Panstenoninae; (2) Perilampidae + Eucharitidae; (3) Chalcididae + Leucospidae + Eurytomidae; (4) Eulophidae: Eulophinae + Tetrastichinae + Entedoninae; and (5) Eupelmidae + Encyrtidae, Mymarommatoidea renders Chalcidoidea paraphyletic in our analyses; however, the taxon sample is too restricted to provide a robust hypothesis. Three previously unreported putative autapomorphies of Chalcidoidea were revealed: (1) presence of an exposed, triangular or diamond-shaped prosternum; (2) presence of a percurrent mesopleural sulcus anteriorly terminating in the acropleuron; and (3) presence of paired metapectal plates lateral to the metafurca.

Within the well-studied Palearctic entomofauna, it is often assumed that the discovery of new species is limited to resolving cryptic species complexes within dark taxa. Herein, we describe a highly distinctive species of Aphanogmus Thomson, 1858 (Hymenoptera: Ceraphronidae) from Germany and provide a COI barcoding sequence for the new species. We present a 3D reconstruction of the holotype based on micro-CT to serve as a cybertype. The females of Aphanogmus kretschmanni Moser sp. nov. are diagnosed by two rows of prominent spines on the ventral edge of the 7th metasomal sternite, a character set that has not previously been found in Hymenoptera. We analyse the functional morphology of the ovipositor mechanism and discuss hypotheses regarding the functional implications of the unique modification of the 7th metasomal sternite. Possible host associations are reviewed and the taxonomic placement of the new species is discussed.