Phylogenomics of the superfamily Dytiscoidea (Coleoptera: Adephaga) with an evaluation of phylogenetic conflict and systematic error.

The beetle superfamily Dytiscoidea, placed within the suborder Adephaga, comprises six families. The phylogenetic relationships of these families, whose species are aquatic, remain highly contentious. In particular the monophyly of the geographically disjunct Aspidytidae (China and South Africa) remains unclear. Here we use a phylogenomic approach to demonstrate that Aspidytidae are indeed monophyletic, as we inferred this phylogenetic relationship from analyzing nucleotide sequence data filtered for compositional heterogeneity and from analyzing amino-acid sequence data. Our analyses suggest that Aspidytidae are the sister group of Amphizoidae, although the support for this relationship is not unequivocal. A sister group relationship of Hygrobiidae to a clade comprising Amphizoidae, Aspidytidae, and Dytiscidae is supported by analyses in which model assumptions are violated the least. In general, we find that both concatenation and the applied coalescent method are sensitive to the effect of among-species compositional heterogeneity. Four-cluster likelihood-mapping suggests that despite the substantial size of the dataset and the use of advanced analytical methods, statistical support is weak for the inferred phylogenetic placement of Hygrobiidae. These results indicate that other kinds of data (e.g. genomic meta-characters) are possibly required to resolve the above-specified persisting phylogenetic uncertainties. Our study illustrates various data-driven confounding effects in phylogenetic reconstructions and highlights the need for careful monitoring of model violations prior to phylogenomic analysis.

Unveiling the diversification dynamics of Australasian predaceous diving beetles in the Cenozoic.

During the Cenozoic, Australia experienced major climatic shifts that have had dramatic ecological consequences for the modern biota. Mesic tropical ecosystems were progressively restricted to the coasts and replaced by arid-adapted floral and faunal communities. Whilst the role of aridification has been investigated in a wide range of terrestrial lineages, the response of freshwater clades remains poorly investigated. To gain insights into the diversification processes underlying a freshwater radiation, we studied the evolutionary history of the Australasian predaceous diving beetles of the tribe Hydroporini (147 described species). We used an integrative approach including the latest methods in phylogenetics, divergence time estimation, ancestral character state reconstruction, and likelihood-based methods of diversification rate estimation. Phylogenies and dating analyses were reconstructed with molecular data from seven genes (mitochondrial and nuclear) for 117 species (plus 12 outgroups). Robust and well-resolved phylogenies indicate a late Oligocene origin of Australasian Hydroporini. Biogeographic analyses suggest an origin in the East Coast region of Australia, and a dynamic biogeographic scenario implying dispersal events. The group successfully colonized the tropical coastal regions carved by a rampant desertification, and also colonized groundwater ecosystems in Central Australia. Diversification rate analyses suggest that the ongoing aridification of Australia initiated in the Miocene contributed to a major wave of extinctions since the late Pliocene probably attributable to an increasing aridity, range contractions and seasonally disruptions resulting from Quaternary climatic changes. When comparing subterranean and epigean genera, our results show that contrasting mechanisms drove their diversification and therefore current diversity pattern. The Australasian Hydroporini radiation reflects a combination of processes that promoted both diversification, resulting from new ecological opportunities driven by initial aridification, and a subsequent loss of mesic adapted diversity due to increasing aridity.

Anisomeriini diving beetles-an Atlantic-Pacific Island disjunction on Tristan da Cunha and Robinson Crusoe Island, Juan Fernández?

Anisomeriini diving beetles contain only two enigmatic species, representing a remarkable disjunction between the Pacific Juan Fernández Islands (Anisomeria bistriata) and the South Atlantic Tristan da Cunha Archipelago (Senilites tristanicola). They belong to the Colymbetinae, which contain 140 species worldwide. Here we aim to reconstruct the evolutionary history of the Anisomerinii and use > 9000 bp DNA sequence data from 13 fragments of 12 loci for a comprehensive sampling of Colymbetinae species. Analyses under different optimization criteria converge on very similar topologies, and show unambiguously that Anisomeria bistriata and Senilites tristanicola belong to the Neotropical Rhantus signatus species group, a comparatively recent clade within Colymbetinae. Anisomeriini therefore are synonomized with Colymbetini and both species are transferred to Rhantus accordingly, resulting in secondary homonymy of Rhantus bistriatus (Brullé, 1835) with Rhantus bistriatus (Bergsträsser, 1778). We propose the replacement name Rhantus selkirki Jäch, Balke & Michat nom. nov. for the Juan Fernández species. Presence of these species on remote islands is therefore not relictary, but the result of more recent range expansions out of mainland South America. Finally, we suggest that Carabdytini should be synonymized with Colymbetini. Our study underpins the Hennigian principle that a natural classification can be derived only from the search for shared apomorphies between species, not from differences.

Review of the genus Sekaliporus Watts, 1997 with description of a new species from northern Australia (Coleoptera: Dytiscidae, Hydroporinae).

Sekaliporus davidi sp. n. is described from northern Australia. It is the second species in the genus. It occurs from the Kimberley region in the northwest of Western Australia to north-eastern Queensland. The new species is morphologically similar to S. kriegi Watts, 1997 described from the Kakadu area in the Northern Territory but well characterized by its constantly larger size, six yellowish markings on elytra, the different form of the apical triangular spine of elytra, and the form of the median lobe. Sekaliporus davidi sp. n. is a lotic species from intermittent creeks and slow flowing rivers and their residual pools. Important species characters (median lobes, parameres and colour patterns) of the two species are figured, and notes on their habitats and distribution are given. Both species are capable of flight and were also collected at light.

Taxonomic revision of Australian Platynectes Régimbart, 1879 (Part I)-four new species from Queensland (Coleoptera: Dytiscidae, Agabinae).

Four species of the genus Platynectes subgenus Gueorguievtes Vazirani, 1976 are described from Queensland, Australia: Platynectes brancuccii sp. n. (Atherton Tableland), P. larsoni sp. n. (Mulgrave Range and Windsor Tableland), P. ponderi sp. n. (Carnarvon Range) and Platynectes weiri sp. n. (White Mountains National Park and Hope Vale Mission). The latter two are the first species of the genus with striae on elytra and the informal P. weiri-species group is established for them. Platynectes brancuccii sp. n. and P. larsoni sp. n. belong to the P. decempunctatus-species group. All four species were collected from small rain forest streams or rest pools of intermittent creeks. Important species characters (median lobes, parameres and colour patterns) of all species are figured, and notes on their distribution and ecology are given. Altogether 17 species of the genus are now known from Australia.

Revision of the Austrelatuspapuensis group with descriptions of 42 new species from New Guinea (Coleoptera, Dytiscidae, Copelatinae).

The Austrelatuspapuensis group is the second species group of the New Guinean representatives of the recently described genus AustrelatusShaverdo 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: Austrelatusaiyurensissp. nov., A.asteiossp. nov., A.bewaniensissp. nov., A.bosaviensissp. nov., A.bundunensissp. nov., A.centralensissp. nov., A.craterensissp. nov., A.decorissp. nov., A.dekaisp. nov., A.epicharissp. nov., A.flavocapitatussp. nov., A.fuscussp. nov., A.herzogensissp. nov., A.inconstanssp. nov., A.iriatoisp. nov., A.kalibumisp. nov., A.kebarensissp. nov., A.kokodensissp. nov., A.leptossp. nov., A.lolokisp. nov., A.lopintolensissp. nov., A.madangensissp. nov., A.maindaisp. nov., A.mamberamosp. nov., A.mianminensissp. nov., A.miltokarenossp. nov., A.noiadisp. nov., A.normanbyensissp. nov., A.ohusp. nov., A.posmanisp. nov., A.procerussp. nov., A.pseudogestroisp. nov., A.pseudomianminensissp. nov., A.robustussp. nov., A.sarartisp. nov., A.sumokedisp. nov., A.wanangensissp. nov., A.wasiorensissp. nov., A.wasurensissp. nov., A.weigelisp. nov., A.yamurensissp. nov., A.yeretuarsp. nov., A.xanthocephalusnabirensisssp. nov. 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.

The effect of geographical scale of sampling on DNA barcoding.

Eight years after DNA barcoding was formally proposed on a large scale, CO1 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 CO1 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.

Limbodessus moni sp. nov., a new high altitudinal diving beetle from the Grasberg in West Papua, Indonesia (Coleoptera: Dytiscidae, Bidessini).

Limbodessus moni sp. nov. is described from Lake Anderson and from small, richly vegetated swampy areas around alpine lakes at 3,970 m a.s.l. near the Grasberg Mine (Carstensz Pyramid) in the Central Mountain Range of New Guinea. The record of the new species marks the altitudinal maximum of a diving beetle in New Guinea. The new species is morphologically similar to L. alexanderi Balke & Hendrich, 2015 in terms of body size and dark coloration; however, both species can be easily separated by the shape of the median lobe and the more moniliform female antennomeres, not forming a conspicuous club as in L. alexanderi. A modified key for all five Limbodessus species from New Guinea and adjacent islands is presented.

Austrelatus gen. nov., a new genus of Australasian diving beetles (Coleoptera, Dytiscidae, Copelatinae), with the discovery of 31 new species from New Guinea.

Herein, Austrelatusgen. nov. (type species: Copelatusirregularis W.J. Macleay, 1871) is described for a distinctive lineage of predominantly Australasian species previously assigned to Copelatus Erichson, 1832. The new genus was retrieved as well supported, monophyletic clade in phylogenetic analysis of DNA sequences data using Bayesian and parsimony approaches. The main morphological diagnostic character of Austrelatus is a complex median lobe of the aedeagus, with evident dorsal and ventral sclerites usually divided in apical half into two lobes of different shape or otherwise modified. Morphological comparison of the new genus with other Copelatinae genera, especially with Copelatus and Exocelina Broun, 1886, and a generic key to the New Guinean Copelatinae are provided. New combinations are established for 31 already described species mainly from the Australian Region (all from Copelatus): Austrelatusadelbert (Megna, Atthakor, Manaono, Hendrich & Balke, 2017), comb. nov.; A.badeni (Sharp, 1882), comb. nov.; A.bakewelli (J. Balfour-Browne, 1939), comb. nov.; A.baranensis (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.bougainvillensis (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.boukali (Hendrich & Balke, 1998), comb. nov.; A.clarki (Sharp, 1882), comb. nov.; A.daemeli (Sharp, 1882), comb. nov.; A.davidi (Wewalka, 2017), comb. nov.; A.deccanensis (Sheth, Ghate & Hájek, 2018), comb. nov.; A.fidschiensis (Zimmermann, 1928), comb. nov.; A.gestroi (Régimbart, 1892), comb. nov.; A.irregularis (W.J. Macleay, 1871), comb. nov.; A.kaszabi (Guignot, 1956), comb. nov.; A.kietensis (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.laevipennis (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.luteomaculatus (Guignot, 1956), comb. nov.; A.maushomi (Sheth, Ghate & Hájek, 2018), comb. nov.; A.neoguineensis (Zimmermann, 1919), comb. nov.; A.nigrolineatus (Sharp, 1882), comb. nov.; A.papuensis (J. Balfour-Browne, 1939), comb. nov.; A.parallelus (Zimmermann, 1920a), comb. nov.; A.schuhi (Hendrich & Balke, 1998), comb. nov.; A.sibelaemontis (Hájek, Hendrich, Hawlitschek & Balke, 2010), comb. nov.; A.strigosulus (Fairmaire, 1878), comb. nov.; A.ternatensis (Régimbart, 1899), comb. nov.; A.uludanuensis (Hendrich & Balke, 1995), comb. nov.; A.urceolus (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.variistriatus (Hájek, Shaverdo, Hendrich & Balke, 2021), comb. nov.; A.wallacei (J. Balfour-Browne, 1939), comb. nov. and A.xanthocephalus (Régimbart, 1899), comb. nov.Austrelatus species from New Guinea are divided into two informal species groups, the A.neoguineensis group and A.papuensis group, and A.fumatosp. nov. and A.setiphallussp. nov. standing aside of them. The A.neoguineensis group is introduced with three previously known species and 29 new species described here based on the morphological characters and Cox1 data: Austrelatusbaliemsp. nov., A.bormensissp. nov., A.brazzasp. nov., A.debulensissp. nov., A.fakfaksp. nov., A.febrisaurisp. nov., A.fojaensissp. nov., A.garainensissp. nov., A.innominatussp. nov., A.lembenensissp. nov., A.lisaesp. nov., A.manokwariensissp. nov., A.mimikasp. nov., A.mirificussp. nov., A.moreguinensissp. nov., A.nadjaesp. nov., A.oksibilensissp. nov., A.pseudoneoguineensissp. nov., A.pseudoksibilensissp. nov., A.rajaampatensissp. nov., A.rouaffersp. nov., A.rugosussp. nov., A.sandaunensissp. nov., A.sarmiensissp. nov., A.securiformissp. nov., A.testegensissp. nov., A.toricellisp. nov., A.vagauensissp. nov., and A.wanggarensissp. nov.Copelatusvagestriatus Zimmermann, 1919, syn. nov. is recognised as a junior subjective synonym of A.clarki (Sharp, 1882). The lectotypes of Copelatusgestroi Régimbart, 1892, C.neoguineensis Zimmermann, 1919 and C.xanthocephalus Régimbart, 1899 are designated. All species are (re)described, and their important species characters (genitalia, habitus, and colour patterns) are illustrated. Keys to all species are provided. The known distribution and habitat preferences of each species are outlined briefly. New Guinean Austrelatus occupy a variety of stagnant water habitats, either lentic sensu stricto, or standing water associated with lotic habitats (e.g., backflows, rockpools, intermittent / ephemeral stream pools).

Eastern Colombian Páramo Liodessus Guignot, 1939 diving beetles are genetically structured, but show signs of hybridization, with description of new species and subspecies (Coleoptera, Dytiscidae).

We studied Liodessus diving beetles from six eastern Colombian Páramo areas, as well as from the Altiplano. We discovered a highly characteristic new species, based on male genital morphology, Liodessussantarositasp. nov., in the Páramo de Guantiva-Rusia. Specimens from the Altiplano around Bogotá, and the Páramos of Almorzadero, Chingaza, Matarredonda, Rabanal y Rio Bogotá and Sumapaz form one clade of genetically similar populations based on mitochondrial Cox1 sequence data. The individuals of this clade are sub-structured according to their geographic distribution. The populations differ from each other mainly in terms of body size and coloration and, at most, subtly in their genital morphology. In two cases, we find putative hybrid populations between Altiplano and Páramo areas. We suggest that the different Páramo populations are in an early phase of speciation, and perhaps already genetically isolated in some cases. They are here assigned subspecies status to highlight these ongoing processes pending more comprehensive geographic sampling and use of genomic data. We refer to this clade as the Liodessusbogotensis complex, containing Liodessusb.bogotensis Guignot, 1953; Liodessusb.almorzaderossp. nov.; Liodessusb.chingazassp. nov.; Liodessusb.lacunaviridis Balke et al., 2021, stat. nov.; Liodessusb.matarredondassp. nov., and Liodessusb.sumapazssp. nov.

Pleistocene climate change promoted rapid diversification of aquatic invertebrates in Southeast Australia.

BACKGROUND: The Pleistocene Ice Ages were the most recent geohistorical event of major global impact, but their consequences for most parts of the Southern hemisphere remain poorly known. We investigate a radiation of ten species of Sternopriscus, the most species-rich genus of epigean Australian diving beetles. These species are distinct based on genital morphology but cannot be distinguished readily by mtDNA and nDNA because of genotype sharing caused by incomplete lineage sorting. Their genetic similarity suggests a Pleistocene origin. RESULTS: We use a dataset of 3858 bp of mitochondrial and nuclear DNA to reconstruct a phylogeny of Sternopriscus using gene and species trees. Diversification analyses support the finding of a recent rapid speciation event with estimated speciation rates of up to 2.40 species per MY, which is considerably higher than the proposed average rate of 0.16 species per MY for insects. Additionally, we use ecological niche modeling and analyze data on habitat preferences to test for niche divergence between species of the recent Sternopriscus radiation. These analyses show that the species can be characterized by a set of ecological variables referring to habitat, climate and altitude. CONCLUSIONS: Our results suggest that the repeated isolation of populations in glacial refugia might have led to divergent ecological adaptations and the fixation of morphological traits supporting reproductive isolation and therefore may have promoted speciation. The recent Sternopriscus radiation fulfills many characteristics of a species flock and would be the first described example of an aquatic insect species flock. We argue that the species of this group may represent a stage in speciation past the species flock condition because of their mostly broad and often non-overlapping ranges and preferences for different habitat types.

Molecular phylogeny of the squeak beetles, a family with disjunct Palearctic-Australian range.

Many higher groups of plants and animals show distributional patterns which have been shown or have at some point in time been suggested to be correlated with plate tectonics and the ancient supercontinents Laurasia and Gondwana. Here, we study the family of squeak beetles (Coleoptera: Adephaga: Hygrobiidae) and its enigmatic distribution pattern, with one species in the Western Palearctic, one in China and four in Australia. We present a molecular phylogeny including five of the six extant species, showing the monophyly of the Australian radiation. We use a molecular clock approach, which indicates that Hygrobiidae is an ancient group dating back to the breakup of Pangea and discuss the possibility of vicariance as explanation for its current distribution.

A new species of Clypeodytes Rgimbart, 1894 from China (Coleoptera, Dytiscidae: Bidessini).

The diving beetle Clypeodytes limpidus sp. nov. is described from western Yunnan, China. It is the second known species of the genus Clypeodytes Rgimbart, 1894 from China and belongs to the subgenus Hypoclypeus Guignot, 1950. It can be distinguished from C. bufo (Sharp, 1890), the only other Chinese Clypeodytes species, by the shape of the median lobe, the more rounded body and the elytral pattern. A Chinese specimen of C. bufo is illustrated, and the species is recorded for the first time for Laos.

Ancient associations of aquatic beetles and tank bromeliads in the Neotropical forest canopy.

Water reservoirs formed by the leaf axils of bromeliads are a highly derived system for nutrient and water capture that also house a diverse fauna of invertebrate specialists. Here we investigate the origin and specificity of bromeliad-associated insects using Copelatinae diving beetles (Dytiscidae). This group is widely distributed in small water bodies throughout tropical forests, but a subset of species encountered in bromeliad tanks is strictly specialized to this habitat. An extensive molecular phylogenetic analysis of Neotropical Copelatinae places these bromeliadicolous species in at least three clades nested within other Copelatus. One lineage is morphologically distinct, and its origin was estimated to reach back to 12-23 million years ago, comparable to the age of the tank habitat itself. Species of this clade in the Atlantic rainforest of southern Brazil and mountain ranges of northern Venezuela and Trinidad show marked phylogeographical structure with up to 8% mtDNA divergence, possibly indicating allopatric speciation. The other two invasions of bromeliad water tanks are more recent, and haplotype distributions within species are best explained by recent expansion into newly formed habitat. Hence, bromeliad tanks create a second stratum of aquatic freshwater habitat independent of that on the ground but affected by parallel processes of species and population diversification at various temporal scales, possibly reflecting the paleoclimatic history of neotropical forests.

A review of Copelatus diving beetles from the Solomon Islands, reporting the discovery of six new species (Coleoptera, Dytiscidae, Copelatinae).

The first account of the genus Copelatus Erichson, 1832 in the Solomon Islands is provided, reporting 10 species for the Archipelago. Six of these are new to science: C. baranensis sp. nov., C. laevipennis sp. nov., C. urceolus sp. nov., and C. variistriatus sp. nov. from Guadalcanal and C. bougainvillensis sp. nov., and C. kietensis sp. nov. from Bougainville. Copelatus tulagicus Guignot, 1942, described from Tulaghi Island of the Solomons, is recorded from Guadalcanal and Santa Isabel for the first time. The widely distributed Australasian C. portior Guignot, 1956 is reported from the Solomon Islands (Guadalcanal and Ontong Java Atoll) for the first time. Two species from Guadalcanal remain unidentified since they are so far known only from a limited number of females.

Taxonomic revision of Australasian diving beetles in the genus Leiodytes Guignot, 1936 (Coleoptera: Dytiscidae, Bidessini).

Bidessus migrator Sharp, 1882, so far assigned to Clypeodytes Régimbart, 1894, and widely distributed in Australia and New Guinea, is re-described. Based on morphological and molecular evidence, it is here transferred to Leiodytes Guignot, 1936. Bidessus loriae Régimbart, 1892 is found to be a junior subjective synonym of L. migrator. We describe the following new species: Leiodytes surianiae sp. nov. (eastern New Guinea, northeast coast of Queensland), and Leiodytes wattsi sp. nov. (southern New Guinea and Darwin area to northern Queensland). We delineate the species using characters such as male genital structure and beetle size, shape and color pattern. Mitochondrial Cox1 data for 27 individuals, representing all three Australasian species, were generated and revealed clusters congruent with the morphological evidence. In Australia Leiodytes only occurs in the tropical and subtropical northern part of the continent. None of the species is endemic to Australia. The species are mainly lentic, occurring in seasonal swamps, flooded meadows and pools of intermittent rivers and temporary creeks.

A new Colombian species of Liodessus diving beetles from the Páramo de Sumapaz (Coleoptera, Dytiscidae, Bidessini).

Liodessuspicinus sp. nov. is described from the Páramo de Sumapaz near Bogota D.C. at 3,500 m above sea level. The species can be distinguished from the other Colombian Liodessus species by its dark coloration, discontinuous habitus, shiny surface of the pronotum and elytron, presence of a distinct occipital line, distinct basal pronotal striae, short or even faint basal elytral striae, as well as by its distinct geographic distribution and cox1 signature.

Coverage and quality of DNA barcode references for Central and Northern European Odonata.

BACKGROUND: Dragonflies and damselflies (Odonata) are important components in biomonitoring due to their amphibiotic lifecycle and specific habitat requirements. They are charismatic and popular insects, but can be challenging to identify despite large size and often distinct coloration, especially the immature stages. DNA-based assessment tools rely on validated DNA barcode reference libraries evaluated in a supraregional context to minimize taxonomic incongruence and identification mismatches. METHODS: This study reports on findings from the analysis of the most comprehensive DNA barcode dataset for Central European Odonata to date, with 103 out of 145 recorded European species included and publicly deposited in the Barcode of Life Data System (BOLD). The complete dataset includes 697 specimens (548 adults, 108 larvae) from 274 localities in 16 countries with a geographic emphasis on Central Europe. We used BOLD to generate sequence divergence metrics and to examine the taxonomic composition of the DNA barcode clusters within the dataset and in comparison with all data on BOLD. RESULTS: Over 88% of the species included can be readily identified using their DNA barcodes and the reference dataset provided. Considering the complete European dataset, unambiguous identification is hampered in 12 species due to weak mitochondrial differentiation and partial haplotype sharing. However, considering the known species distributions only two groups of five species possibly co-occur, leading to an unambiguous identification of more than 95% of the analysed Odonata via DNA barcoding in real applications. The cases of small interspecific genetic distances and the observed deep intraspecific variation in Cordulia aenea (Linnaeus, 1758) are discussed in detail and the corresponding taxa in the public reference database are highlighted. They should be considered in future applications of DNA barcoding and metabarcoding and represent interesting evolutionary biological questions, which call for in depth analyses of the involved taxa throughout their distribution ranges.

A Baltic amber species of the diving beetle genus Coptotomus Say, 1830 (Coleoptera: Dytiscidae: Coptotominae).

We provide the first report of the Nearctic diving beetle subfamily Coptotominae Van den Branden, 1885 for the Paleactic Region, based on † Coptotomus balticus sp. n. from Baltic amber. Coptotomus Say, 1830 is otherwise distributed with five extant species and one subspecies in the Nearctic Region. The new species is the smallest species of the genus and thus readily separated from the extant taxa.

Hydaticus (Prodaticus) hauthi sp. nov., a new diving beetle from the cloud forest in the Cordillera El Sira, Peru (Coleoptera: Dytiscidae).

A new species of the genus Hydaticus Leach, 1817, subgenus Prodaticus Sharp, 1882 (Coleoptera: Dytiscidae) has been discovered in the mountains of Cerros del Sira, Peru. It is here described as Hydaticus (Prodaticus) hauthi sp. nov.. It is morphologically similar to the Peruvian H. panguana Megna, Balke, Apenborn Hendrich, 2019. The new species differs from H. panguana by its almost complete black dorsal surface and the shape of the median lobe. Diagnostic characters of both species, including illustrations of male genitalia and habitus, are presented, and a modified key for the 12 Neotropical species is provided.