Publications by authors named "David T Bilton"

Relictorygmus Seidel, Minoshima, Arriaga-Varela & Fikáček, 2018, the only known African genus of the hydrophilid subfamily Cylominae, currently includes two lentic species from the far southwestern Cape of South Africa. Here Relictorygmus riparius sp. nov.

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The larvae of three species of the South African endemic water beetle genus Prosthetops Waterhouse, 1879 are described and illustrated for the first time. The second and third instar larvae of Prosthetops nitens (Péringuey, 1892), as well as third instar larva of P. megacephalus (Boheman, 1851) and P.

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Species distributed across wide elevational gradients are likely to experience local thermal adaptation and exhibit high thermal plasticity, as these gradients are characterised by steep environmental changes over short geographic distances (i.e., strong selection differentials).

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The success of non-native species (NNS) invasions depends on patterns of dispersal and connectivity, which underpin genetic diversity, population establishment and growth. In the marine environment, both global environmental change and increasing anthropogenic activity can alter hydrodynamic patterns, leading to significant inter-annual variability in dispersal pathways. Despite this, multi-generational dispersal is rarely explicitly considered in attempts to understand NNS spread or in the design of management interventions.

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An intricate interplay between evolutionary and demographic processes has frequently resulted in complex patterns of genetic and phenotypic diversity in alpine lineages, posing serious challenges to species delimitation and biodiversity conservation planning. Here we integrate genomic data, geometric morphometric analyses and thermal tolerance experiments to explore the role of Pleistocene climatic changes and adaptation to alpine environments on patterns of genomic and phenotypic variation in diving beetles from the taxonomically complex Agabus bipustulatus species group. Genetic structure and phylogenomic analyses revealed the presence of three geographically cohesive lineages, two representing trans-Palearctic and Iberian populations of the elevation-generalist A.

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Protozantaena gigantea sp. nov. is described, based on specimens collected from residual pools in a drying seasonal river in Namaqualand, Northern Cape Province, South Africa.

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Eupotemus tuberculatus sp. nov. is described on the basis of two specimens discovered during recent field work in South Africa.

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Invasive alien species are considered one of the greatest threats to global biodiversity, and are particularly problematic in aquatic systems. Given the foundational role of macrophytes in most freshwaters, alien aquatic plant invasions may drive strong bottom-up impacts on recipient biota. Crassula helmsii (New Zealand pygmyweed) is an Australasian macrophyte, now widespread in northwest Europe.

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Southern Afrotemperate Forest is concentrated in the southern Cape region of South Africa and whilst it is relatively well known botanically, the fauna, specifically the aquatic invertebrate fauna, is poorly documented. The majority of remaining intact forest habitat is contained within the Garden Route National Park (GRNP), which straddles the provincial boundary between the Western and Eastern Cape. This study undertakes a survey of the water beetle fauna inhabiting the GRNP.

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The Southern African endemic torridincolid water beetle genus Delevea Reichardt, 1976 is revised, based largely on recently collected material from the Republic of South Africa. Significant range extensions are provided for the two previously described species, Delevea bertrandi Reichardt, 1976 and D. namibiensis Endrödy-Younga, 1997, these taxa apparently being endemic to the Fynbos Biome in the Western Cape Province and semi-arid, summer rainfall, areas of the Great Escarpment in Namibia and South Africa, respectively.

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Non-native species are spreading at an unprecedented rate over large spatial scales, with global environmental change and growth in commerce providing novel opportunities for range expansion. Assessing the pattern and rate of spread is key to the development of strategies for safeguarding against future invasions and efficiently managing existing ones. Such assessments often depend on spatial distribution data from online repositories, which can be spatially biased, imprecise, and lacking in quantity.

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The complete mitogenome sequence of Talpa martinorum, a recently described Balkan endemic mole, was assembled from next generation sequence data. The mitogenome is similar to that of the three other Talpa species sequenced to date, being 16,835 bp in length, and containing 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, an origin of L-strand replication, and a control region or D-loop. Compared to other Talpa mitogenomes sequenced to date, that of T.

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Protozantaena birdi sp. nov. is described, based on specimens collected from the Compassberg and Winterberg ranges in the Eastern Cape Great Escarpment, South Africa; the seventh known species of the genus.

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Thermal history can plastically alter the response of ectotherms to temperature, and thermal performance curves (TPCs) are powerful tools for exploring how organismal-level performance varies with temperature. Plasticity in TPCs may be favoured in thermally variable habitats, where it can result in fitness benefits. However, thermal physiology remains insufficiently studied for freshwater insects despite freshwater biodiversity being at great risk under global change.

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A new genus, Riberazantaena gen. nov., is erected to accommodate Protozantaena grebennikovi Perkins, 2009 and Riberazantaena latissima sp.

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We revise the Afrotropical species group, motivated by the discovery of new diversity in Kenya and South Africa. Whilst is mainly a holarctic genus, the group is restricted to high altitude regions of eastern Africa and temperate parts of South Africa, from where we describe the southernmost in the world. The following new species are introduced: from Mount Kenya in central Kenya, a widespread species in South Africa, from the Kamiesberg and northeastern Cederberg ranges in the Northern and Western Cape Provinces of South Africa and from the Agulhas Plain, Western Cape Province, South Africa.

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Diving as a lifestyle has evolved on multiple occasions when air-breathing terrestrial animals invaded the aquatic realm, and diving performance shapes the ecology and behaviour of all air-breathing aquatic taxa, from small insects to great whales. Using the largest dataset yet assembled, we show that maximum dive duration increases predictably with body mass in both ectotherms and endotherms. Compared to endotherms, ectotherms can remain submerged for longer, but the mass scaling relationship for dive duration is much steeper in endotherms than in ectotherms.

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Article Synopsis
  • The Dytiscoidea superfamily, which includes aquatic beetles, is made up of six families, and their evolutionary relationships are still debated, especially regarding the Aspidytidae family.
  • Using phylogenomic methods, researchers confirmed that Aspidytidae is monophyletic and suggested it is closely related to the Amphizoidae family, although this relationship needs more support.
  • The study emphasizes the complexity and potential confounding issues in phylogenetic analysis, indicating that more data types may be necessary to resolve ongoing uncertainties in their evolutionary placements.
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Beetles have colonized water many times during their history, with some of these events involving extensive evolutionary radiations and multiple transitions between land and water. With over 13,000 described species, they are one of the most diverse macroinvertebrate groups in most nonmarine aquatic habitats and occur on all continents except Antarctica. A combination of wide geographical and ecological range and relatively accessible taxonomy makes these insects an excellent model system for addressing a variety of questions in ecology and evolution.

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The genus Leielmis was recently revised by Bilton (2017), who established the identity of the type species Leielmis georyssoides (Grouvelle, 1890), and described two new taxa: Leielmis gibbosus Bilton, 2017, widespread in the Cape Fold Mountains and Leielmis hirsutus Bilton, 2017, known to date only from a single site at high altitude in the Groote Winterhoek mountains. A distinctive new species of Leielmis was discovered in a high altitude stream in 2017 in the Hexrivierberge, being collected whilst the generic revision was in press! This species is described below, and a modified key to Leielmis species presented. In light of this discovery it appears likely that further work at high altitude will reveal additional species in the Cape.

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Meladema Laporte, 1835 is a genus of large diving beetles, found in the Western Palaearctic, from the Canary Islands and Madeira to western Turkey (Bilton Ribera 2017). The genus currently contains four species: the widespread M. coriacea Laporte, 1835, distributed from the Canary Islands to Turkey and ranging from southern France and the central Balkans south to the central Sahara, two Atlantic Island endemics, M.

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Parhydraena d'Orchymont, 1937 currently includes 19 species, 17 of which are endemic to South Africa (Perkins 2009; Bilton 2014). Most species of the genus are fully aquatic, but a few, together with members of other genera of Parhydraenini, occupy moist habitats rich in organic debris (Perkins 2009). These so-called humicolous habitats (Perkins Balfour-Browne 1994) occur both beside water and elsewhere, and have been colonised a number of times by primarily aquatic hydraenid lineages, particularly in Africa and Australasia (e.

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