Hydrophilid Beetles Research Articles

Two New Phoretic Species of Heterostigmatic Mites (Acari: Prostigmata: Neopygmephoridae and Scutacaridae) on Australian Hydrophilid Beetles (Coleoptera: Hydrophilidae).

Simple SummaryHeterostigmatic mites are globally very diverse, and many are generally phoretic or parasitic on insects. However, the Australian fauna of phoretic heterostigmatic mites is almost unexplored. Here, we describe two new species of Allopygmephorus and Archidispus (Acari: Prostigmata: Heterostigmata) found phoretic on semiaquatic beetles. Our findings report both genera for the first time from Australia.Many heterostigmatic mites (Acari: Prostigmata: Heterostigmata) display a wide range of symbiotic interactions, from phoresy to parasitism, with a variety of insects. Australia is expected to harbour a rich diversity of heterostigmatic mites; however, its phoretic fauna and its host associations remain mainly unexplored. We conducted a short exploration of Australian insect-associated phoretic mites in summer 2020 and found two new phoretic heterostigmatic species on a semiaquatic hydrophilid beetle species, Coelostoma fabricii (Montrouzier, 1860) (Coleoptera: Hydrophilidae). Here, we describe these two new species, Allopygmephorus coelostomus sp. nov. (Neopygmephoridae) and Archidispus hydrophilus sp. nov. (Scutacaridae), which both belong to the superfamily Pygmephoroidea. Both species are distinct from their congeners, with a plesiomorphic character, bearing a median genital sclerite (mgs). Our study reports both genera for the first time from Australia.

New state records of hydrophilid beetles (Coleoptera: Hydrophilidae) in Mexico

Se presentan nuevos registros estatales de Hydrophilus (Dibolocelus) purpurascens Régimbart, 1901 para Chiapas y Berosus (Enoplurus) punctatissimus LeConte, 1852 para San Luis Potosí, México. También se incluye un mapa con la distribución geográfica conocida de ambas especies.

Kruia rediscovered: phylogenetic implications, larval morphology, and biology of an enigmatic hydrophilid beetle from western Africa (Coleoptera: Hydrophilidae)

Kruia rediscovered: phylogenetic implications, larval morphology, and biology of an enigmatic hydrophilid beetle from western Africa (Coleoptera: Hydrophilidae)

Coprophagous Hydrophilid Beetles (Coleoptera, Hydrophilidae, Sphaeridiinae) Distribution in the Polish Carpathians.

Research on coprophagous beetles of the Hydrophilidae family in the Polish Carpathians was conducted from 2011 to 2013. The beetles were caught using baited traps. The research sites were selected to take into account both the horizontal diversity of habitat conditions and the vertical diversity associated with elevation above sea level. During the study, 9589 coprophagous hydrophilid individuals were collected, representing 17 species and five genera. Two species that were new to Poland were found: Cercyon tatricus and Pachysternum capense. The vertical ranges of the individual species of coprophagous hydrophilid beetles within the Polish Carpathians were determined as well as the elevations above sea level, with the highest and lowest species richness of this group of insects. The capture of Pachysternum capense in the Tatra Mountains may indicate the existence of an unrecognized path of migration of small insects from Southern to Northern Europe. The route and mechanisms of their migration are discussed.

Morphology and biology of the flower‐visiting water scavenger beetle genus Rygmodus (Coleoptera: Hydrophilidae)

AbstractHydrophilidae (water scavenger beetles) is well known as an aquatic beetle family; however, it contains ca. 1,000 secondarily terrestrial species derived from aquatic ancestors. The New Zealand endemic genus Rygmodus White is a member of the hydrophilid subfamily Cylominae, which is the early‐diverging taxon of the largest terrestrial lineage (Cylominae + Sphaeridiinae) within the Hydrophilidae. In this paper we report that Rygmodus beetles are pollen‐feeding flower visitors as adults, but aquatic predators as larvae. Based on analyses of gut contents and a summary of collecting records reported on museum specimen labels, adult Rygmodus beetles are generalists feeding on pollen of at least 13 plant families. Rygmodus adult mouthparts differ from those of other (saprophagous) hydrophilid beetles in having the simple scoop‐like apex and mola with roughly denticulate surface, resembling the morphology found in pollen‐feeding staphylinid beetles. Larvae were found along the sides of streams, under stones and in algal mats and water‐soaked moss; one collected larval specimen was identified using DNA barcoding of two molecular markers, mitochondrial cytochrome oxidase 1 (cox1) and nuclear histone 3 (H3). Larvae of two species, Rygmodus modestus and Rygmodus sp., are described in detail and illustrated; they closely resemble ambush‐type predatory larvae of the hydrophilid tribe Hydrophilini in the head morphology. Rygmodus is the only known hydrophilid beetle with adults and larvae inhabiting different environments.

Fireworks under the microscope: a spectacular new species of Zodiomyces from the Thaxter collection

A new species of Zodiomyces (Ascomycota, Laboulbeniales) is described, Z. rhizophorus, parasitic on a hydrophilid beetle (Coleoptera, Hydrophilidae) from Trinidad. This species was discovered during the examination of the slides of Laboulbeniales made by Roland Thaxter. It is characterized by numerous long, slender, multicellular and multiseriate outgrowths at the base of the receptacle. Thaxter’s outstanding illustrations have set a standard in the field of mycology; we provide a review of the methods he employed in the preparation of these illustrations.

Flowering mechanisms, pollination strategies and floral scent analyses of syntopically co-flowering Homalomena spp. (Araceae) on Borneo.

In this study, the flowering mechanisms and pollination strategies of seven species of the highly diverse genus Homalomena (Araceae) were investigated in native populations of West Sarawak, Borneo. The floral scent compositions were also recorded for six of these species. The selected taxa belong to three out of four complexes of the section Cyrtocladon (Hanneae, Giamensis and Borneensis). The species belonging to the Hanneae complex exhibited longer anthesis (53-62h) than those of the Giamensis and Borneensis complexes (ca. 30h). Species belonging to the Hanneae complex underwent two floral scent emission events in consecutive days, during the pistillate and staminate phases of anthesis. In species belonging to the Giamensis and Borneensis complexes, floral scent emission was only evident to the human nose during the pistillate phase. A total of 33 volatile organic compounds (VOCs) were detected in floral scent analyses of species belonging to the Hanneae complex, whereas 26 VOCs were found in samples of those belonging to the Giamensis complex. The floral scent blends contained uncommon compounds in high concentration, which could ensure pollinator discrimination. Our observations indicate that scarab beetles (Parastasia gestroi and P.nigripennis; Scarabaeidae, Rutelinae) are the pollinators of the investigated species of Homalomena, with Chaloenus schawalleri (Chrysomelidae, Galeuricinae) acting as a secondary pollinator. The pollinators utilise the inflorescence for food, mating opportunities and safe mating arena as rewards. Flower-breeding flies (Colocasiomyia nigricauda and C. aff. heterodonta; Diptera, Drosophilidae) and terrestrial hydrophilid beetles (Cycreon sp.; Coleoptera, Hydrophilidae) were also frequently recovered from inflorescences belonging to all studied species (except H.velutipedunculata), but they probably do not act as efficient pollinators. Future studies should investigate the post-mating isolating barriers among syntopically co-flowering Homalomena sharing the same visiting insects.

The systematics and evolution of pinworms (Nematoda: Oxyurida: Thelastomatoidea) from invertebrates.

The nematode order Oxyurida is unique in including species for which definitive host ranges are broad and may include vertebrate or invertebrate hosts. The superfamily Thelastomatoidea is a highly diverse assemblage of oxyurids occurring in cockroaches, diplopods, hydrophilid beetles, passalid beetles, several other coleopteran larvae, mole crickets, and, with few representative species documented, other arthropod hosts. Published research and revision of the Thelastomatoidea, particularly in the 1980s and 1990s, provided several interesting hypotheses on the systematics and evolution of this group. In this review, these hypotheses are examined in the context of recent advances in taxonomy, discovery of additional species diversity and distribution, and preliminary phylogenetic hypotheses that have been proposed. There continues to remain a paucity of phylogenetic data that explore the phylogenetic relationships of the Thelastomatoidea and their relationships to vertebrate-parasitizing pinworms. A combination of mitochondrial and nuclear DNA sequences for representative species across all of the major lineages will be important for more robust phylogenetic hypotheses. Much broader geographical and host taxon sampling is necessary to determine true diversity of the Thelastomatoidea. Modern approaches to species descriptions, such as improvements in light and scanning electron microscopy and the use of molecular approaches to matching male and female nematodes, can also be applied to improve our understanding of the evolution of these fascinating parasites.

Insect Fauna of the Late Miocene Locality of Öhningen (Germany) Less Diverse than Reported: An Example of the Hydrophilid Beetles (Coleoptera)

The fossils originally assigned to the family Hydrophilidae (Coleoptera, Polyphaga) from the late Miocene locality of Öhningen (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 Öhnigen fauna by O. Heer. The diversity of the hydrophilid beetles in Öhningen is thus lower than previously reported, but still being slightly higher compared to other European Paleogene and Neogene localities.

When a beetle is too small to carry phoretic mites? A case of hydrophilid beetles (Coleoptera: Hydrophilidae) andUropoda orbicularis(Acari: Mesostigmata)

The aim of our study was to determine the limit of a beetle’s body size below which it is not able to carry phoretic mites. We tested the hypothesis that body size of the carrier is the vital factor in selecting a host in mites with facultative and nonspecific phoresy. The study was conducted on beetles of the family Hydrophilidae and deutonymphs of the mite Uropoda orbicularis (Müller, 1776). Among 20 species of hydrophilids collected, only 7 carried deutonymphs. The smallest hydrophilids with body lengths below 2.32 mm did not carry deutonymphs. These were Cercyon analis (Paykull, 1798), Cercyon nigriceps (Marsham, 1802), Cercyon pygmaeus (Illiger, 1801), Cercyon terminatus (Marsham, 1802), Cryptopleurum crenatum (Kugelann, 1794), Cryptopleurum minutum (Fabricius, 1775), Cryptopleurum subtile Sharp, 1884, and Megasternum concinnum (Marsham, 1802). On the contrary, the largest beetles, of the genus Sphaeridium Fabricius, 1775, were most heavily and frequently occupied by phoretic deutonymphs. Most representatives of the genus Cercyon Leach, 1817 did not carry mites or had a very low mite burden. Our study indicates that beetle infestation by nonspecific phoretic mites is strongly influenced by beetle body size.

An Aquatic Water Scavenger Beetle in Early Miocene Amber from the Dominican Republic (Coleoptera: Hydrophilidae)

We describe a fossil hydrophilid beetle Anacaena paleodominica sp. nov. from the Early Miocene amber of the Dominican Republic, which is the only definitive amber inclusion of the family Hydrophilidae documented. The species belongs to the Recent Anacaena suturalis species group known from the Nearctic, Neotropical, and Australian regions. The fossil demonstrates that representatives of the species group may already have been widespread and common by the Early Miocene, and indicates a possible Miocene/post-Miocene extinction of the aquatic insect fauna on the island of Hispaniola.

On the identity of the fossil hydrophilid beetles from the Tertiary localities in the southern part of the Upper Rhine Graben (Coleoptera: Hydrophilidae, Dytiscidae)

This study focuses on the fossil beetles assigned previously to the family Hydrophilidae described from the localities in the southern part of the Upper Rhine Graben: Brunstatt (France, Alsace) and Kleinkems (Germany, Baden-Württemberg) (both dated ca. to Eocene-Oligocene boundary, 34 Ma). The identity of Escheria convexa Förster, 1891 is fixed by the designation of its neotype, the species is redescribed, illustrated, transferred from the hydrophilid genus Hydrobius Leach, 1815 to the genus Copelatus Erichson, 1832 (Coleoptera: Adephaga: Dytiscidae) and compared with other fossil representatives of Copelatus. The identity of the remaining three species, Hydrobius crassipunctatus (Förster, 1891), Hydrobius dimidiatus (Förster, 1891) and Hydrobius punctulatus (Förster, 1891),is briefly evaluated on the basis of the original descriptions and illustrations only, because their types were lost or destroyed during World War II; all three species are removed from the fossil record of the Hydrophiloidea and placed into Polyphaga incertae sedis. The geology and stratigraphy of Brunnstatt and Kleinkems are discussed briefly.

Fossil Hydrophilid Beetles (Coleoptera: Hydrophilidae) of the Late Oligocene Rott Formation (Germany)

Abstract:Fossil water scavenger beetles (Coleoptera: Hydrophilidae) of the latest Oligocene Rott Formation are revised, based on the examination of the type specimens, as well as numerous additional material from Statz (Los Angeles) and Kastenholz (Bonn) collections. Seven hydrophilid species are recognized, five of which are reliably attributed to the following genera: Berosus morticinus (von Heyden and von Heyden, 1866), Paracymus excitatus (von Heyden and von Heyden, 1866), Paracymus sp., Hydrobiomorpha fraterna (von Heyden, 1859), and Hydrophüus rottensis (Statz, 1939). Coccinella? protogaeae Germar 1837 is attributed to the subtribe Hydrophilina, and Cymbiodyta? austera Statz 1939 to the subfamily Hydrophilinae. Hydrous ebeninus Statz 1939 and Paracymus excitatus (form 3) are excluded from the Hydrophiloidea. Berosus capitatus Statz 1939 is synonymized with Berosus morticinus, and Hydrous neptunus von Heyden and von Heyden 1866 with Hydrobiomorpha fraterna. Lectotypes of Philydrus morticinus von Heyden and von Heyden 1866 and Hydrous ebeninus Statz 1939 are designated. The significance of the hydrophilid fossils for paleoecological reconstructions of the former Rott Lake is briefly discussed.

Feedbacks between community assembly and habitat selection shape variation in local colonization

1. Non-consumptive effects of predators are increasingly recognized as important drivers of community assembly and structure. Specifically, habitat selection responses to top predators during colonization and oviposition can lead to large differences in aquatic community structure, composition and diversity. 2. These differences among communities due to predators may develop as communities assemble, potentially altering the relative quality of predator vs. predator-free habitats through time. If so, community assembly would be expected to modify the subsequent behavioural responses of colonists to habitats containing top predators. Here, we test this hypothesis by manipulating community assembly and the presence of fish in experimental ponds and measuring their independent and combined effects on patterns of colonization by insects and amphibians. 3. Assembly modified habitat selection of dytscid beetles and hylid frogs by decreasing or even reversing avoidance of pools containing blue-spotted sunfish (Enneacanthus gloriosus). However, not all habitat selection responses to fish depended on assembly history. Hydrophilid beetles and mosquitoes avoided fish while chironomids were attracted to fish pools, regardless of assembly history. 4. Our results show that community assembly causes taxa-dependent feedbacks that can modify avoidance of habitats containing a top predator. Thus, non-consumptive effects of a top predator on community structure change as communities assemble and effects of competitors and other predators combine with the direct effects of top predators to shape colonization. 5. This work reinforces the importance of habitat selection for community assembly in aquatic systems, while illustrating the range of factors that may influence colonization rates and resulting community structure. Directly manipulating communities both during colonization and post-colonization is critical for elucidating how sequential processes interact to shape communities.

Spatial heterogeneity of trophic pathways in the invertebrate community of a temperate bog

Summary 1. To examine spatial heterogeneity of trophic pathways on a small scale (<5 m diameter), we conducted dual stable isotope (δ13C and δ15N) analyses of invertebrate communities and their potential food sources in three patchy habitats [sphagnum lawn (SL), vascular‐plant carpet (VC) and sphagnum carpet] within a temperate bog (Mizorogaike Pond, Kyoto, Japan).2. In total, 19 invertebrate taxa were collected from the three habitats, most of which were stenotopic, i.e. collected from a single habitat. Amongst the habitats, significant variation was observed in the isotopic signatures of dominant plant tissues and their detrital matter [benthic particulate organic matter (BPOM)], both of which were potential organic food sources for invertebrates. Site‐specific isotopic variation amongst detritivores was found in δ13C but not in δ15N, reflecting site‐specificity in the isotopic signatures of basal foods. The eurytopic hydrophilid beetle Helochares striatus was found in all habitats, but showed clear site variation in its isotopic signatures, suggesting that it strongly relies on foods within its own habitat.3. The most promising potential foods for detritivores were the dead leaf stalks of a dominant plant in the VC and BPOM in the SL and carpet. An isotopic mixing model (IsoSource version 1.3.1) estimated that aquatic predators rely on unknown trophic sources with higher δ13C than detritus, whereas terrestrial predators forage on allochthonous as well as autochthonous prey, suggesting that the latter predators might play key roles in coupling between habitats.4. Our stable isotope approach revealed that immobile detritivores are confined to their small patchy habitats but that heterogeneous trophic pathways can be coupled by mobile predators, stressing the importance of habitat heterogeneity and predator coupling in characterising food webs in bog ecosystems.

К фауне жуков-водолюбов (Coleoptera: Hydrophilidae) Кемеровской области

К фауне жуков-водолюбов (Coleoptera: Hydrophilidae) Кемеровской области

Turkish hydrophilidae (Coleoptera) III. Genus Hydrochara Berthold 1827 with the description of a new species, Hydrochara major sp. n.

A new species of hydrophilid beetle, Hydrochara major sp. n., is described from sea level in northern Anatolia (Asiatic Turkey). The key and list of Hydrochara spp. known from Turkey are presented with additional distributional data.

Oviposition behavior partitions aquatic landscapes along predation and nutrient gradients

That individuals attempt to minimize the ratio of mortality risk/growth rate (μ/g) when foraging within individual habitat patches is well established. Do species partition among spatially discrete communities embedded in complex landscapes in a similar manner? We investigated how 3 ovipositing species (2 Hyla treefrogs and a hydrophilid beetle, Tropisternus lateralis) responded to simultaneous gradients of nutrients and predation risk. Species partitioned our experimental metacommunity primarily by reducing oviposition with fish. Tropisternus positively responded to increased nutrients, but the effect decreased with increasing risk, as predicted by μ/g theory. Use of fish habitats by Tropisternus was unrelated to breeding intensity. In contrast, Hyla showed no nutrient response but oviposited with fish only on nights with high breeding activity. Behavioral responses to the spatial distribution of resources and risk among discrete patches generated substantial variation in habitat-specific colonization rates, which has been identified as a primary mechanism generating both community and metacommunity structure.

Trichurispora wellgundis n. g., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae) Parasitizing Adult Water Scavenger Beetles, Tropisternus collaris (Coleoptera: Hydrophilidae) in the Texas Big Thicket

Trichurispora wellgundis n. g., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae) is described from the adults of the water scavenger beetle Tropisternus collaris (Coleoptera: Hydrophilidae) collected from B A Steinhagen Lake in the Cherokee Unit of the Big Thicket National Preserve, Tyler County, Texas, U.S.A. Trichurispora is distinguished from known genera of Hirmocystidae by a distinct ''trichurisiform'' oocyst that is hesperidiform in outline, comprising a fusiform oocyst with shallowly ovoid terminal knobs or caps. Oocyst residua are present but confined to a central fusiform residuum vacuole. Adult and larval hydrophilid beetles represent distinctly different opportunities for parasite colonization and diversification. Gregarines have been reported from both adult and larval hydrophilid beetles, but no species and no genus is reported from both adult and larval hosts. In fact, gregarine taxic richness is often more disparate between adult and larval beetles of the same species than between host beetle species. This is the first report of a septate gregarine from an adult hydrophilid beetle in the Nearctic.

Distributional, systematic and ecological notes on newly recorded lowland hydrophilid beetles from Algeria

Specimens of aquatic Coleoptera were collected in various parts of northeastern Algeria in different surveys in 2005. Three species of hydrophilid were collected, and are reported here. Although the species Limnoxenus niger (Gamelin, 1790) and Coleostoma hispanicum (Kuster, 1848) are frequently collected and presented in larger beetle collections, there are only a few definite records from Algeria. All samples were collected from lowland and moderately highland habitats in northeastern Algeria (maximum 800 m a.s.l.). The beetles were killed using ethyl acetate or in 70 % alcohol solution. Aedeagophores of the beetles, cleaned with brushes were dissected under a stereo microscope and left in 10 % KOH solution for 1-2 h. Photographs were taken using a SMZ-1500 Nikon type 104 microscope.