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A new species from Guangxi, China is described. New records are provided for the following species: Wewalka, 2000 and Wewalka, 2000 from Zhejiang, and Bian, Guo & Ji, 2013 from Guizhou. Additional records are also given for some other Chinese species. The habitus and male genitalia of the new species are illustrated. An updated key and a checklist of all Chinese species of are provided.

We describe for the first time, the larvae of Cybister (Cybister) lewisianus Sharp, 1873, an endangered species of diving beetle in Japan, emphasizing the chaetotaxy of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. larvae are characterized by a longer third article of antenna 3 than the sum of the first and second articles; rounded apex of parietal setae 1-3; labium seta 8 absent; elongated trochanter seta 4, not multi-branched; rounded apex of abdominal setae 1, 12, and 13 (instar I); narrow lateral projections of the frontoclypeus; pronotum without two dark-brown longitudinal stripes dorsally (instar III); and the base of the thick row of small setae on the inner edge of the mandible angulate and projecting medially (all instars).

Eight years after DNA barcoding was formally proposed on a large scale, COI sequences are rapidly accumulating from around the world. While studies to date have mostly targeted local or regional species assemblages, the recent launch of the global iBOL project (International Barcode of Life), highlights the need to understand the effects of geographical scale on Barcoding's goals. Sampling has been central in the debate on DNA Barcoding, but the effect of the geographical scale of sampling has not yet been thoroughly and explicitly tested with empirical data. Here, we present a COI data set of aquatic predaceous diving beetles of the tribe Agabini, sampled throughout Europe, and use it to investigate how the geographic scale of sampling affects 1) the estimated intraspecific variation of species, 2) the genetic distance to the most closely related heterospecific, 3) the ratio of intraspecific and interspecific variation, 4) the frequency of taxonomically recognized species found to be monophyletic, and 5) query identification performance based on 6 different species assignment methods. Intraspecific variation was significantly correlated with the geographical scale of sampling (R-square = 0.7), and more than half of the species with 10 or more sampled individuals (N = 29) showed higher intraspecific variation than 1% sequence divergence. In contrast, the distance to the closest heterospecific showed a significant decrease with increasing geographical scale of sampling. The average genetic distance dropped from > 7% for samples within 1 km, to < 3.5% for samples up to > 6000 km apart. Over a third of the species were not monophyletic, and the proportion increased through locally, nationally, regionally, and continentally restricted subsets of the data. The success of identifying queries decreased with increasing spatial scale of sampling; liberal methods declined from 100% to around 90%, whereas strict methods dropped to below 50% at continental scales. The proportion of query identifications considered uncertain (more than one species < 1% distance from query) escalated from zero at local, to 50% at continental scale. Finally, by resampling the most widely sampled species we show that even if samples are collected to maximize the geographical coverage, up to 70 individuals are required to sample 95% of intraspecific variation. The results show that the geographical scale of sampling has a critical impact on the global application of DNA barcoding. Scale-effects result from the relative importance of different processes determining the composition of regional species assemblages (dispersal and ecological assembly) and global clades (demography, speciation, and extinction). The incorporation of geographical information, where available, will be required to obtain identification rates at global scales equivalent to those in regional barcoding studies. Our result hence provides an impetus for both smarter barcoding tools and sprouting national barcoding initiatives— smaller geographical scales deliver higher accuracy.

Most subterranean animals are assumed to have evolved from surface ancestors following colonization of a cave system; however, very few studies have raised the possibility of “subterranean speciation” in underground habitats (i.e., obligate cave-dwelling organisms [troglobionts] descended from troglobiotic ancestors). Numerous endemic subterranean diving beetle species from spatially discrete calcrete aquifers in Western Australia (stygobionts) have evolved independently from surface ancestors; however, several cases of sympatric sister species raise the possibility of subterranean speciation. We tested this hypothesis using vision (phototransduction) genes that are evolving under neutral processes in subterranean species and purifying selection in surface species. Using sequence data from 32 subterranean and five surface species in the genus Paroster (Dytiscidae), we identified deleterious mutations in long wavelength opsin (lwop), arrestin 1 (arr1), and arrestin 2 (arr2) shared by a sympatric sister-species triplet, arr1 shared by a sympatric sister-species pair, and lwop and arr2 shared among closely related species in adjacent calcrete aquifers. In all cases, a common ancestor possessed the function-altering mutations, implying they were already adapted to aphotic environments. Our study represents one of the first confirmed cases of subterranean speciation in cave insects. The assessment of genes undergoing pseudogenization provides a novel way of testing modes of speciation and the history of diversification in blind cave animals.

Two diving beetle species (Coleoptera, Dytiscidae) from the extant genus Copelatus Erichson are documented from early Miocene Mexican amber. Copelatus chiapas new species is described based on a series of specimens of both sexes. Copelatus chiapas n. sp. is the third species of the subfamily Copelatinae described from amber and the first fossil diving beetle for which distinct sexual dimorphism is documented. The other species remains identified to genus level only, due to poor structural visibility. Key morphological characters of the species are illustrated. UUID: http://zoobank.org/0127be7a-bcb5-41da-9363-283d5cd49738

A doubt has arisen about the taxonomic status of within the species group due to morphological similarities and lack of molecular data. In this study, a comprehensive morphological and molecular analysis of specimens from Central Europe was conducted, focusing on the Hungarian population. Morphological comparisons of genital structures revealed age-dependent variations, suggesting a gradual transition from to . Molecular analysis of COI sequences further supported this hypothesis, showing minimal genetic differences among most specimens, with only one individual exhibiting distinctiveness. Therefore, must be regarded as a junior synonym of . Our findings also highlight the need for additional multi-marker studies covering a broader geographic range and including both molecular and morphological approaches to elucidate the taxonomic and phylogenetic relationships within this species group. The inclusion of Hungarian samples notably enriched the diversity of haplotypes, emphasizing the importance of expanding sampling efforts in future research.

Beavers (Castor spp.) are ecosystem engineers that induce local disturbance and ecological succession, which turns terrestrial into aquatic ecosystems and creates habitat heterogeneity in a landscape. Beavers have been proposed as a tool for biodiversity conservation and ecosystem restoration. So far, most research has compared biodiversity in beaver wetlands and non-beaver wetlands, but few studies have explored how beaver-created succession affects specific taxa. In this study, we investigated how water beetles responded to different successional stages of wetlands in a beaver-disturbed landscape at Evo in southern Finland. We sampled water beetles with 1-L activity traps in 20 ponds, including: 5 new beaver ponds, 5 old beaver ponds, 5 former beaver ponds, and 5 never engineered ponds. We found that beaver wetlands had higher species richness and abundance than non-beaver wetlands, and that new beaver wetlands could support higher species richness (321%) and abundance (671%) of water beetles compared to old beaver wetlands. We think that higher water beetle diversity in new beaver ponds has resulted from habitat amelioration (available lentic water, shallow shores, aquatic vegetation, and low fish abundance) and food source enhancement (an increase of both dead and live prey) created by beaver dams and floods. We conclude that using beavers as a tool, or imitating their way of flooding, can be beneficial in wetland restoration if beaver population densities are monitored to ensure the availability of newly colonizable sites.

The group is the second species group of the New Guinean representatives of the recently described genus Shaverdo et al., 2023. The group is mainly defined by distinct scale- and/or spinula-like surface structures of the dorsal sclerite of the median lobe. The species group already contains four described species and 42 new species and one subspecies treated here: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , A checklist and identification key to New Guinean species of the group are provided and important diagnostic characters are illustrated. Data on the species distributions and habiat preferences are given.

This study presents the first inventory of Hydradephaga beetles from the Iberá wetlands, a natural reserve located in the province of Corrientes, Argentina. A total of 80 taxa were recognised, of which 62 are identified at the species level and 18 at the genus level. Of the four Hydradephaga families present in Argentina, Dytiscidae is the richest in terms of the number of genera and species (25 genera, 43 species), followed by Noteridae (6 genera, 32 species), Gyrinidae (2 genera, 3 species), and Haliplidae (1 genus, 2 species). The following five species are recorded for the first time in Argentina: Copelatus cf. inornatus Sharp, 1882; Bidessodes cf. evanidus Young, 1986; Neobidessus trilineatus (Zimmermann, 1925); Haliplus nieseri van Vondel & Spangler, 2008; and Suphisellus cf. pereirai Guignot, 1958. Additionally, eight species are reported for the first time in the province of Corrientes: Meridiorhantus orbignyi (Balke, 1992); Celina cf. parallela (Babington, 1842); Laccophilus cf. obliquatus Régimbart, 1889; Laccophilus cf. paraguensis Régimbart, 1903; Haliplus ornatipennis Zimmermann, 1921; Hydrocanthus paraguayensis Zimmermann, 1928; Mesonoterus crassicornis (Régimbart, 1889); and Suphisellus cf. rufipes (Sharp, 1882). The high diversity of Hydradephaga beetles recorded highlights the ecological significance of this protected area.

We review Bayesian approaches to model testing in general and to the assessment of topological hypotheses in particular. We show that the standard way of setting up Bayes factor tests of the monophyly of a group, or the placement of a sample sequence in a known reference tree, can be misleading. The reason for this is related to the well-known dependency of Bayes factors on model-specific priors. Specifically, when testing tree hypotheses it is important that each hypothesis is associated with an appropriate tree space in the prior. This can be achieved by using appropriately constrained searches or by filtering trees in the posterior sample, but in a more elaborate way than typically implemented. If it is difficult to find the appropriate tree sets to be contrasted, then the posterior model odds may be more informative than the Bayes factor. We illustrate the recommended techniques using an empirical test case addressing the issue of whether two genera of diving beetles (Coleoptera: Dytiscidae), Suphrodytes and Hydroporus, should be synonymized. Our refined Bayes factor tests, in contrast to standard analyses, show that there is strong support for Suphrodytes nesting inside Hydroporus, and the genera are therefore synonymized.