A paradox indeed: description of genitalia and clarification of the subtribal classification of Pachyonychis paradoxus Clark and Pachyonychus paradoxus Melsheimer (Coleoptera: Chrysomelidae: Galerucinae: Alticini).

Pachyonychis paradoxus Clark, 1860 and Pachyonychus paradoxus Melsheimer, 1847 are two species of Alticini whose strikingly similar names have led to significant confusion in the past. Recent study of American Oedionychina Chapuis, 1875 raised doubts about the validity of the subtribal placement of Pachyonychis Clark. Although general characteristics put this genus in Oedionychina, other features, especially the unusual shape of the pronotum, suggested that this monotypic genus would belong in Monoplatina Chapuis, 1875 instead. To collect evidence for the validity of its current placement, we compared external and genitalic morphology of both species to other members of Monoplatina and Oedionychina. Here we present images and descriptions of female genitalia for both species and male genitalia of Pachyonychus paradoxus Melsheimer, to our knowledge the first of their kind, and we conclude that the evidence supports the current subtribal placement of these two genera. Lectotypes are designated for both Pachyonychis paradoxus Clark and Pachyonychus paradoxus Melsheimer.

An annotated checklist of the leaf beetles (Coleoptera, Chrysomelidae) from El Salvador, with additions from the Bechyné collection in the Royal Belgian Institute of Natural Sciences.

A checklist of the species of leaf beetles (Coleoptera: Chrysomelidae) of El Salvador is presented based on data from literature and a digitization project of the Bechyné collection of the Royal Belgian Institute of Natural Sciences (RBINS). The RBINS collections contain a total of 2797 individual chrysomelid specimens from El Salvador, sorted into 89 species and 132 genera. In total, the current checklist contains 420 species, of which 33 are new records for El Slavador from the Bechyné collection. In these collections, there are also ten nomina nuda named by Bechyné, which need further study. The leaf beetle diversity in El Salvador, partly due to the country's unstable political history, remains poorly studied, and many (new) species await discovery. This checklist provides a baseline for further study in El Salvador and nearby region.

Inter- and Intrafield Distribution of Cereal Leaf Beetle Species (Coleoptera: Chrysomelidae) in Belgian Winter Wheat.

Cereal leaf beetles (CLBs), a group of chrysomelid beetles of the genus Oulema (Coleoptera: Chrysomelidae), are well-known pest insects of small-grain cereals in many countries of the Northern hemisphere. Due to the small differences in morphology of species within this genus, classification up to species level remains a challenging task. Since an accurate view of species composition is important for developing targeted control strategies, the goal of this study was to unravel the Oulema species composition in Flanders' wheat fields. During three subsequent years at a series of different fields, Oulema species were collected and classified up to species level (2016: 28 fields, 2017: 30 fields, and 2018: 23 fields). This study reveals that the population consists of four different species: Oulema melanopus, Oulema duftschmidi, and Oulema obscura were most frequently encountered, while Oulema rufocyanea was only marginally present. Furthermore, the population was highly dynamic, as the population share of each species varied between different growing seasons and between the various sampling events within each season. The distance from the field edge had a minor influence on the species composition, but the abundance of beetles increased with the distance to the field edge. A discriminant analysis revealed that based on the measurements of various body parts, an accurate classification up to species level is possible. In conclusion, we observed that the population densities fluctuated within and between years, resulting in variable incidence of CLB in winter wheat fields in the Flanders region.