New methods in taxonomy and systematics can influence the overall practice of formally naming and describing biodiversity. DNA barcoding has been controversial since its emergence, but now, large scale species descriptions exclusively based on barcodes have created what can be called a ‘new quality of performance’. Its limitations are discussed from different perspectives: nomenclature, general pragmatism, and problems of DNA-based species delimitation in the light of the central aim of achieving a robust and stable nomenclature of organisms, essential for all applications of biodiversity research. This issue needs to be addressed to prevent restraining the progress of taxonomy and its ability to contribute to modern science.

Color polymorphism offers rich opportunities for studying the eco‐evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. We explored the color morph diversity and composition in aChrysomela lapponicaleaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species. We obtained information on 13 617 specimens of this beetle from museums, private collections, and websites. These specimens (collected from 1830–2020) originated from 959 localities spanning 33° latitude, 178° longitude, and 4200 m altitude. We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism (quantified by the Shannon diversity index) and in the relative frequencies of individual color morphs. The highest level of polymorphism was found at high latitudes and altitudes. The color morphs differed in their climatic requirements; composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year, longitude, mean July temperature and between‐year temperature fluctuations. The proportion of melanic beetles, in line with the thermal melanism hypothesis, increased with increasing latitude and altitude and decreased with increasing climate seasonality. Melanic morph frequencies also declined during the past century, but only at high latitudes and altitudes where recent climate warming was especially strong. The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments, presumably due to the different climatic requirements of coexisting color morphs.

For 160 years, Anthrenus pimpinellae isabellinus Kster, 1848 has been considered a subspecies of A. pimpinellae Fabricius, 1775. However, habitus shape differs between the subspecies with A. p. isabellinus being broader than A. p. pimpinellae and resembling more closely A. dorsatus Mulsant & Rey, 1868. Here A. p. pimpinellae and A. p. isabellinus, are examined to look for evidence that they comprise a single taxonomic unit. Habitus and genital structures are considered, and the universal animal barcode region of the mitochondrial cytochrome oxidase I gene is sequenced. The results of the morphological, morphometric, and genetic analyses mirror each other perfectly and suggest that A. p. isabellinus is the same species as A. dorsatus rather than being a subspecies of A. pimpinellae. The very small intraspecific DNA sequence variation supports the view that A. dorsatus and A. p. isabellinus belong to a single species that diverges considerably from A. p. pimpinellae. Morphology, including genital structure, is congruent with the genetic data and provides a powerful way of resolving species organisation in these widespread beetles. In view of these findings, Anthrenus isabellinus Kster, 1848 is restored to full species status and Anthrenus dorsatus Mulsant & Rey, 1868 becomes its new junior subjective synonym.

A taxonomic review of the Chinese species of the genus Xenicotela Bates, 1884 is presented. A new species, Xenicotela griseomaculata sp. nov., is described from Chongqing, China, and a new combination, Xenicotela convexicollis (Gressitt, 1942) comb. nov., is proposed.

Data on the collection of the genus Epepeotes Pascoe, 1866 deposited in the Natural History Museum, London are presented. A total of 23 species/subspecies, including type specimens of 18 names, of them 13 valid, are recorded. Epepeotes uncinatus lineatopunctatus Breuning, 1960 is restored to subspecies-level status. Lectotypes are designated for Epepeotes uncinatus uncinatus Gahan, 1888 and Epepeotes andamanicus Gahan, 1893. Epepeotes luscus luscus (Fabricius, 1787) is newly recorded in Cambodia and Singapore, and Epepeotes uncinatus uncinatus Gahan, 1888 is newly recorded in Bangladesh. Images of the type and other significant specimens are provided for 23 taxa, mainly for the first time.

Aporrhipis flexilis Pascoe, 1887 is the sole species of a monospecific genus of beetles from Brazil, originally described in the family Ripiphoridae. Despite the fact that this genus was moved to Lycidae, its correct tribal placement remains uncertain. In this study, A. flexilis is redescribed, its tribal placement is discussed, and it is tentatively placed within the Calopterini, Acroleptina. The problems of distinguishing the Acroleptina from the Leptolycini are highlighted by this case, and a plea is made for additional specimens to help resolve this conundrum.