Testing the validity of Northern European species in the Chrysis ignita species group (Hymenoptera: Chrysididae) with DNA barcoding.

Containing more than a hundred species, the Chrysis ignita species group is the largest and one of the most taxonomically challenging groups in its genus. It has not been possible to resolve the taxonomy of the group using traditional methods due to the lack of robust diagnostic morphological characters. Here we present the results of a molecular analysis designed to delimit species in the Chrysis ignita group for the first time; using mitochondrial sequence data for 364 in-group specimens consisting of all 18 species known to occur in Northern Europe. Two mitochondrial loci were analysed: a COI gene fragment, and a continuous DNA sequence consisting of 16S rRNA, tRNAVal, 12S rRNA and ND4. Two approaches were employed for delimiting species: (1) genetic distance analysis based on the standard COI barcode sequences and; (2) phylogenetic analysis of the COI fragment together with rRNA genes. Both analyses yielded trees with similar topology, but support values for nodes were higher using the second approach. Fifteen species were distinguished in all analyses: Chrysis angustula Schenck, 1856, C. brevitarsis Thomson, 1870, C. clarinicollis Linsenmaier, 1951, C. corusca Valkeila, 1971, C. fulgida Linnaeus, 1761, C. ignita (Linnaeus, 1758), C. impressa Schenck, 1856, C. iris Christ, 1791, C. leptomandibularis Niehuis, 2000, C. longula Abeille de Perrin, 1879, C. ruddii Shuckard, 1837, C. schencki Linsenmaier, 1968, C. subcoriacea Linsenmaier, 1959, C. terminata Dahlbom, 1854 and C. vanlithi Linsenmaier, 1959. The specific status of C. mediata Linsenmaier, 1951 and C. solida Haupt, 1957 was not resolved. Included unidentified specimens grouped in three clusters, two of which are distinctly delimited and apparently represent cryptic species. The specific status of the unidentified samples in the third cluster remained unclear. Moreover, our data suggest the existence of additional cryptic species currently lumped under the names C. pseudobrevitarsis Linsenmaier, 1951 and C. schencki Linsenmaier, 1968. In conclusion, our results derived from analysis of mitochondrial loci strongly support the specific status of the majority of currently recognised species in the Chrysis ignita species group, and suggest the existence of additional cryptic species in Northern Europe. Thus, considering the difficulties that often arise during species determination based on morphological characters, the mtDNA loci used here appear highly suitable for assisting species delimitation in this group as well as identification of specimens. 

Ecological Speciation without Morphological Differentiation? A New Cryptic Species of Diodontus Curtis (Hymenoptera, Pemphredonidae) from the Centre of Europe.

Upon exploring the mitotype diversity of the aphid-hunting wasp, Diodontus tristis, we revealed specimens with highly divergent mitotypes from two localities in Lithuania and nesting in clayey substrate, while the specimens with typical mitotypes were found nesting in sandy sites. The comparison of inter- and intra-specific distances and application of delimitation algorithms supported the species status of the clay-nesting populations. Using a set of DNA markers that included complete or partial sequences of six mitochondrial genes, three markers of ribosomal operon, two homeobox genes, and four other nuclear genes, we clarified the phylogenetic relationships of the new cryptic species. The endosymbiotic bacteria infestation was checked, considering the option that the divergent populations may represent clades isolated by Wolbachia infection; however, it did not demonstrate any specificity. We found only subtle morphological differences in the new clay-nesting species, D. argillicola sp. nov.; the discriminant analysis of morphometric measurements did not reliably segregate it as well. Thus, we provide the molecular characters of the cryptic species, which allow confident identification, its phylogenetic position within the genus, and an updated identification key for the D. tristis species group.

Revealing a Novel Potential Pest of Plum Trees in the Caucasus: A Species Resembling the European Leaf-Mining Stigmella plagicolella, Nepticulidae.

In instances of severe infestations, Nepticulidae larvae can inflict damage on cultivated plants. Previously, it was assumed that the Prunus-feeding Nepticulidae have continuous distribution from Europe to the neighboring Caucasus. During recent fieldwork in the Caucasus, leaf mines were found on plum trees that initially resembled those of Stigmella plagicolella (Stainton) in Europe. However, upon rearing the adults, significant differences emerged, leading to the hypothesis that a different Prunus-feeding species exists in the Caucasus; this challenges previous records in Western Asia. This paper presents the outcomes of our morphological, molecular, and statistical investigations, unveiling S. colchica sp. nov., a previously unknown potential plum-tree pest. Distinguished by male genitalia characteristics, the new species differs from S. plagicolella. The inter- and intraspecific divergences between S. colchica sp. nov. and S. plagicolella range from 3.5% to 6.02%. Moreover, the utilized delimitation algorithms reliably clustered two species separately, as does our mitotype network. A statistical analysis also shows a discernible trend between the leaf mines of S. colchica sp. nov. and S. plagicolella. This unexpected discovery not only documents a new potential pest, enhancing our understanding of the Caucasian fauna, but also contributes to the broader biological inventory.

Nesting biology and phylogenetic relationships of the parasitoid-hunting wasp Lindenius pygmaeus armatus (Vander Linden, 1829) (Hymenoptera: Crabronidae).

Nests of Lindenius pygmaeus armatus were examined in northern Poland in Kowalewo Pomorskie and Sierakowo. Adults were encountered from late May to late July. The nests were built in sandy areas and wasteland. Seven nests were observed, of which two were dug up and their structure was examined. The channel was approximately 2.5 mm in diameter and 8-10 cm in the length. The material removed during digging was placed near the nest entrance. The main burrow led to 3-5 cells. The cocoons were approximately 5-7 mm long and 2.5-3.5 mm wide. Females of L. p. armatus provided their nest cells with chalcid wasps averaging 14 prey items per cell. Parasitoids Myrmosa atra and kleptoparasites Senotainia conica were observed entering the burrows. Both females and males of L. p. armatus were detected on the flowers of Achillea millefolium, Peucedanum oreoselinum, Daucus carota, and Tanacetum vulgare. The article also includes phylogenetic relationships of Western Palearctic Lindenius species.

A new leafmining pest of guava: Hesperolyra guajavifoliae sp. nov., with comments on the diagnostics of the endemic Neotropical genus Hesperolyra van Nieukerken (Lepidoptera, Nepticulidae).

We describe a new pest of guava (Psidium guajava L.), Hesperolyra guajavifoliae Stonis & Vargas, sp. nov., that was recently discovered in western Colombia. Hesperolyra van Nieukerken is a small, Neotropical genus of pygmy moths (Nepticulidae). We re-examine and document the complex morphology of the male genitalia of the generic type species, H. diskusi (Puplesis & Robinson). We discuss the diagnostics and composition of the genus and provide a simple pictorial differentiation scheme for all currently known representatives of the genus. The new species is illustrated with photographs of the adults, some of the immature stages, male and female genitalia, and leaf mines. A link to the COI barcodes of H. guajavifoliae sp. nov. is provided and the relationship of Hesperolyra to other genera is discussed.