Hydrobius

Abstract: The chiefly Holarctic Hydrobius species complex (Coleoptera, Hydrophilidae) currently consists of Hydrobius arcticus Kuwert, 1890, and three morphological variants of Hydrobius fuscipes (Linnaeus, 1758): var. fuscipes, var. rottenbergii and var. subrotundus in northern Europe. Here molecular and morphological data are used to test the species boundaries in this species complex. Three gene segments (COI, H3 and ITS2) were sequenced and analyzed with Bayesian methods to infer phylogenetic relationships. The Generalized Mixed Yule Coalescent (GMYC) model and two versions of the Bayesian species delimitation method BPP, with or without an a priori defined guide tree (v2.2 & v3.0), were used to evaluate species limits. External and male genital characters of primarily Fennoscandian specimens were measured and statistically analyzed to test for significant differences in quantitative morphological characters. The four morphotypes formed separate genetic clusters on gene trees and were delimited as separate species by GMYC and by both versions of BPP, despite specimens of Hydrobius fuscipes var. fuscipes and Hydrobius fuscipes var. subrotundus being sympatric. Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii could only be separated genetically with ITS2, and were delimited statistically with GMYC on ITS2 and with BPP on the combined data. In addition, six or seven potentially cryptic species of the Hydrobius fuscipes complex from regions outside northern Europe were delimited genetically. Although some overlap was found, the mean values of six male genital characters were significantly different between the morphotypes (p < 0.001). Morphological characters previously presumed to be diagnostic were less reliable to separate Hydrobius fuscipes var. fuscipes from Hydrobius fuscipes var. subrotundus, but characters in the literature for Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii were diagnostic. Overall, morphological and molecular evidence strongly suggest that Hydrobius arcticus and the three morphological variants of Hydrobius fuscipes are separate species and Hydrobius rottenbergii Gerhardt, 1872, stat. n. and Hydrobius subrotundus Stephens, 1829, stat. n. are elevated to valid species. An identification key to northern European species of Hydrobius is provided.

Abstract: In this study, we recorded the occurrence of 28 species and one subspecies of water scavenger beetles (Coleoptera: Hydrophilidae) belonging to 12 genera ( Paracymus, Anacaena , Berosus , Chaetarthria , Enochrus , Helochares, Hydrobius, Hydrochara, Laccobius, Coelostoma, Cercyon and Cryptopleurum ) based on the inventories conducted between 2007-2008. Of these, Anacaena rufipes, Anacaena lutescens, Cercyon ustulatus, Cryptopleurum crenatum, Enochrus bicolor, Enochrus fuscipennis, Enochrus quadripunctatus , Enochrus melanocephalus , Helochares obscurus, Hydrobius fuscipes, Hydrochara dichroma, Laccobius halophilus, Paracymus aeneus, Paracymus chalceolus and Paracymus scutellaris were new record for the Hydrophilidae fauna of Black Sea region .

Abstract: The water scavenger beetle tribe Hydrobiusini contains 47 species in eight genera distributed worldwide. Most species of the tribe are aquatic, although several species are known to occur in waterfalls or tree mosses. Some members of the tribe are known to communicate via underwater stridulation. While recent morphological and molecular-based phylogenies have affirmed the monophyly of the tribe as currently circumscribed, doubts remain about the monophyly of included genera. Here we use morphological and molecular data to infer a species-level phylogeny of the Hydrobiusini. The monophyly of the tribe is decisively supported, as is the monophyly of most genera. The genus Hydrobius was found to be polyphyletic, and as a result the genus Limnohydrobius stat. rev. is removed from synonymy with Hydrobius, yielding three new combinations: L. melaenus comb.n., L. orientalis comb.n., and L. tumbius comb.n. Recent changes to the species-level taxonomy of Hydrobius are reviewed. The morphology of the stridulatory apparatus has undergone a single remarkable transformation within the lineage, from a simple, unmodified pars stridens to one that is highly organized and complex. We present an updated key to genera, revised generic diagnoses and a list of the known distributions for all species within the tribe.

Abstract: The fossils originally assigned to the family Hydrophilidae (Coleoptera, Polyphaga) from the late Miocene locality of Ohningen (southern Germany) are revised. Nine hydrophilid species are recognized, most of them representing the tribe Hydrophilini. Five species are reliably assigned to genera: Hydrochara noachica (Heer, 1847), n. comb. (=Hydrophilus rehmanni Heer, 1847, n. syn.), Hydrobiomorpha braunii (Heer, 1847), n. comb. (=Hydrous escheri Heer, 1862, n. syn.), Hydrobiomorpha heeri n. sp., Hydrophilus spectabilis Heer, 1847 (=Hydrophilus knorrii Heer, 1847, n. syn., =Hydrophilus giganteus Heer, 1862, n. syn.), and Hydrophilus vexatorius Heer, 1847. Two taxa are treated as Hydrophilini incertae sedis: Hydrophilopsis elongata Heer, 1862, and Hydrous ovalis Heer, 1862. Two species represent Hydrophilidae incertae sedis: Escheria ovalis Heer, 1847 and E. bella Heer, 1862. The fossil genus Hydrophilopsis Heer, 1862 likely represents the modern genera Sternolophus Solier, 1834 or Hydrobiomorpha Blackburn, 1888, the fossil genus Escheria Heer, 1847 likely represents some modern genus within the Hydrophilini or Hydrobiusini. Six taxa are excluded from the Hydrophiloidea: Helophorus magnus Heer, 1862, H. exilis Heer, 1862 (possibly belonging to Curculionidae), Hydrobius couloni Heer, 1862 and H. godeti Heer, 1862 (both possibly belonging to Curculionidae: Zygopinae), Hydrophilus braunii var. minor Heer, 1862, and Hydrophilus stenopterus Heer, 1862 (likely a leaf fossil). Our revision revealed a rather high amount of inaccurate family and genus assignments and a moderate amount of species-level synonymy in the original treatment of Ohnigen fauna by O. Heer. The diversity of the hydrophilid beetles in Ohningen is thus lower than previously reported, but still being slightly higher compared to other European Paleogene and Neogene localities.