Comparative genomics provides insights into molecular adaptation to hypermetamorphosis and cantharidin metabolism in blister beetles (Coleoptera: Meloidae).

Blister beetles (Coleoptera: Meloidae) are currently subdivided into three subfamilies: Eleticinae (a basal group), Nemognathinae, and Meloinae. These are all characterized by the endogenous production of the defensive terpene cantharidin (CA), whereas the two most derived subfamilies show a hypermetamorphic larval development. Here, we provide novel draft genome assemblies of five species sampled across the three blister beetle subfamilies (Iselma pallidipennis, Stenodera caucasica, Zonitis immaculata, Lydus trimaculatus, and Mylabris variabilis) and performed a comparative analysis with other available Meloidae genomes and the closely-related canthariphilous species (Pyrochroa serraticornis) to disclose adaptations at a molecular level. Our results highlighted the expansion and selection of genes potentially responsible for CA production and metabolism, as well as its mobilization and vesicular compartmentalization. Furthermore, we observed adaptive selection patterns and gain of genes devoted to epigenetic regulation, development, and morphogenesis, possibly related to hypermetamorphosis. We hypothesize that most genetic adaptations occurred to support both CA biosynthesis and hypermetamorphosis, two crucial aspects of Meloidae biology that likely contributed to their evolutionary success.

Taxonomic and faunistic study of four almost unknown Brazilian Meloidae (Coleoptera)

ABSTRACT The Brazilian fauna of Meloidae is poorly studied, even though it includes more than 160 species. In this paper, we aimed at widening the knowledge on four species of blister beetles from this country. Specifically, we defined the uncertain range of Tetraonyx angulicollis, as extended in south-eastern Brazil rather than in Mexico, and implemented the description of the species with figures. We studied the taxonomy and distribution of three almost unknown species of Nemognatha from Brazil, São Paulo State, providing descriptions and figures of sexual characters and colour variability of N. beauregardi, to which is probably referable as a junior synonym of N. plaumanni, of N. rufoscutellaris and of N. cfr. gounellei. Moreover, we assigned these three species to the subgenus Pauronemognatha, recently recorded from South America.

Molecular Characterization of Kunitz-Type Protease Inhibitors from Blister Beetles (Coleoptera, Meloidae).

Protease inhibitors are widely studied since the unrestricted activity of proteases can cause extensive organ lesions. In particular, elastase activity is involved in the pathophysiology of acute lung injury, for example during SARS-CoV-2 infection, while serine proteases and thrombin-like proteases are involved in the development and/or pathology of the nervous system. Natural protease inhibitors have the advantage to be reversible and with few side effects and thus are increasingly considered as new drugs. Kunitz-type protease inhibitors (KTPIs), reported in the venom of various organisms, such as wasps, spiders, scorpions, and snakes, have been studied for their potent anticoagulant activity and widespread protease inhibitor activity. Putative KTPI anticoagulants have been identified in transcriptomic resources obtained for two blister beetle species, Lydus trimaculatus and Mylabris variabilis. The KTPIs of L. trimaculatus and M. variabilis were characterized by combined transcriptomic and bioinformatics methodologies. The full-length mRNA sequences were divided on the base of the sequence of the active sites of the putative proteins. In silico protein structure analyses of each group of translational products show the biochemical features of the active sites and the potential protease targets. Validation of these genes is the first step for considering these molecules as new drugs for use in medicine.

Revision of the Hycleus sexmaculatus species group (Coleoptera: Meloidae, Mylabrini).

In this study, the blister beetles belonging to the Hycleus sexmaculatus species group are revised. Morphological characters are described and figured for each species and keys to both male and female are provided. Hycleus hayki new species from Southwest Iran is described and the following new synonymies are proposed: Mylabris triangulifera ab. reitterioides Mader 1929 = Hycleus bipunctatus (Olivier, 1811) new synonymy; Mylabris triangulifera ab. bushirensis Mader 1929 = Hycleus bipunctatus (Olivier, 1811) new synonymy; Mylabris javeti Marseul, 1870 = Hycleus colligatus (Redtenbacher, 1850) new synonymy; Mylabris javeti umbilicatus Kaszab, 1958 = Hycleus colligatus (Redtenbacher, 1850) new synonymy; Hycleus amrishi Makhan, 2012 = Hycleus cingulatus (Faldermann, 1837) new synonymy. Additional remarks which rectify previous errors in the identification of the species are provided. The taxonomic positions of Zonabris soumacovi Pic, 1930 and Zonabris sialanus Pic, 1929 are also discussed. Phylogenetic relationships of the species, based on a subset of available species inferred from molecular data are proposed, and some morphologically defined subgroups of species are distinguished with the molecular support. The geographic and ecological distributions of all the species are defined, and a detailed list of localities is provided. The ecological information including phenology, elevation and host plants of the species are summarized in a table. Based on literature records, collections and recently collected data, the distribution of the sexmaculatus species and their biogeographic characteristics are discussed.

Phylogeny, biogeography and systematics of the hyper-diverse blister beetle genus Hycleus (Coleoptera: Meloidae).

Hycleus is a hyper-diverse genus of blister beetles including ~500 species widely distributed in the Old World, currently divided into three "sections" and into 45 "phenetic" species groups according to morphological characters. Recently the monophyly of Hycleus was questioned pointing out its paraphyly with respect to the genera Ceroctis and Paractenodia. In this study, we built a time-calibrated phylogenetic tree based on DNA sequence data from mitochondrial and nuclear genes obtained from 125 species, to understand the phylogenetic relationships among the species of this genus, to infer the biogeographic processes behind their diversification, and to assess their taxonomy and classification. Our results identified four main lineages one of which included the species belonging to Ceroctis and Paractenodia; therefore, both taxa are now referred to Hycleus as new synonyms. The three described sections of Hycleus resulted polyphyletic and are rejected, whereas several species groups represented well supported clades. Hycleus likely originated in Africa during the Early Miocene (~20 Mya), and subsequently spread in Europe and western Asia. Later, in the Late Miocene (~6 Mya) a Saharo-Sindian group branched off from the Palaearctic lineage, whereas the Oriental Region was colonized following a dispersal event through the Arabian Peninsula from the Afrotropical Region (~5 Mya).