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A first glimpse into the biogeographic affinities of the shallow benthic communities from the sub-Antarctic Crozet archipelago
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Sub-Antarctic islands are expected to show a high degree of endemicity due to their remoteness. However, biogeographic affinities in the sub-Antarctic remain poorly understood, especially in the marine realm. Sub-Antarctic islands being at the crossroads between Antarctic and cold temperate regions, biodiversity characterization and biogeographic analyses are a priority for monitoring and rapidly assessing variations associated with environmental changes. One underexplored sub-Antarctic area is Crozet, a protected archipelago located halfway between Antarctica and South Africa. In this study, we investigated the shallow-water Crozet macrofaunal diversity, distribution patterns and biogeographic affinities based on the examination of fieldwork specimens via a thorough morphological identification and a genetic characterisation. The resulting dataset provides an important baseline for further studies and conservation strategies, compiling the first genetic and taxonomic database for the Crozet archipelago. In total, 100 morphotypes were found, belonging to nine different phyla, among whicharthropods(32), molluscs (18)and echinoderms (17) were the richest. Forty-seven morphotypes were identified to the species level, among which 20 were reported in Crozet for the first time. This confirms that Crozet is a poorly known region, even compared to other sub-Antarctic areas. A large proportion of species (62%) had circum Southern Ocean or circum sub Antarctic distributions. These species were mostly shared with Kerguelen (72%), the Magellan Province (64%), and Prince Edward Islands (64%), confirming the patterns found in macroalgae and specific macrofaunal groups. However, this large-distribution statement needs to be counterbalanced by the detection (genetic data) of more restricted distributions than expected in four study cases (the tanaid Apseudes spectabilis, the nudibranch Doris kerguelenensis, the polychaete Neanthes kerguelensis and the chiton Hemiarthrum setulosum). Considering that most morphotypes had no genetic data available from other regions, the proportion of morphotypes with restricted distribution is likely to increase alongside future investigations. In addition, we also found a few cases of unrecognized diversity that might lead to the descriptions of new species, some likely to be endemic to Crozet (e.g., within the polychaete genus Harmothoe and the bryozoan genus Antarctothoa). Altogether, this stresses the need to maintain conservation efforts in Crozet and pursue integrative investigations in order to highlight and protect its unusual diversity
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Rediscovery and redescription of Dixonius siamensis (Boulenger, 1899) (Squamata: Gekkonidae), type species of the genus, with lectotype designation
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We redescribe the type material of Phyllodactylus siamensis Boulenger, 1899, type species of the Southeast Asian gekkonid genus Dixonius Bauer, Good & Branch, 1997, using external morphology and cranial osteology (by Micro-Computed Tomography, µ-CT). There is some evidence that the type series contains more than one species; we hence designate a lectotype in order to stabilize nomenclature and provide more precision on the geographical location of the type locality. Because the current concept of Dixonius siamensis auctorum is incomplete and composite, we provide a revised diagnosis based on the presently designated lectotype and a paralectotype from the same locality, as well as observations on new material from the type locality and the first photographs of live topotypical individuals. We regard Dixonius siamensis as probably geographically restricted to the Dong Phaya Yen mountain range in central Thailand, and the numerous published mentions of this species from outside this range likely refer to other or undescribed taxa. We treat Phyllodactylus burmanicus Annandale, 1905 from Tavoy, southern Myanmar, as a valid species, as Dixonius burmanicus comb. nov.
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Vertebral morphology and intracolumnar variation of the iconic African viperid snake Atheris (Serpentes, Viperidae)
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We here provide a detailed description of the vertebral morphology of the African arboreal viperid snakes of the genus Atheris. Vertebrae of three different species of the genus, i.e., Atheris desaixi, Atheris hispida, and Atheris katangensis, were investigated via the aid of μCT (micro‐computed tomography) scanning. We describe several vertebrae from different regions of the vertebral column for all three species, starting from the atlas‐axis complex to the caudal tip, in order to demonstrate important differences regarding the intracolumnar variation. Comparison of these three species shows an overall similar general morphology of the trunk vertebrae among the Atheris species. We extensively compare Atheris with other known viperids. As the sole arboreal genus of Viperinae the prehensile nature of the tail of Atheris is reflected in its caudal vertebral morphology, which is characterized by a high number of caudal vertebrae but also robust and anteroventrally oriented pleurapophyses as a skeletal adaptation, linked with the myology of the tail, to an arboreal lifestyle. We anticipate that the extensive figuring of these viperid specimens will also aid identifications in paleontology.
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Le crâne attribué au saint roi mérovingien Dagobert II. Étude historique et anthropologique.
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When History and legend meet forensic anthropology, it can lead to complex research. We owe it to chance, which allowed us to study a skull, part of the Treasury of the Sainte-Waudru collegiate Church in Mons (Belgium). Various documents have been studied and we have maintained contacts with the historians of the City of Stenay (France) and with the Circle of Saint-Dagobert, venerating since 679, Dagobert II, the king murdered on this date and became the protector of this locality. The strangeness of the lesion observed on this skull allowed us to study various weapons from this period in order to search and find very useful matches. Modern datation techniques (radiocarbon) however, have reversed the course of this story and excluded the belonging of this skull to one of the last Merovingian kings.
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A 1500-year record of North Atlantic storm flooding from lacustrine sediments, Shetland Islands (UK)
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Severe storm flooding poses a major hazard to the coasts of north-western Europe. However, the long-term recurrence patterns of extreme coastal flooding and their governing factors are poorly understood. Therefore, high-resolution sedimentary records of past North Atlantic storm flooding are required. This multi-proxy study reconstructs storm-induced overwash processes from coastal lake sediments on the Shetland Islands using grain-size and geochemical data, and the re-analysis of historical data. The chronostratigraphy is based on Bayesian age–depth modelling using accelerator mass spectrometry 14C and 137Cs data. A high XRF-based Si/Ti ratio and the unimodal grain-size distribution link the sand layers to the beach and thus storm-induced overwash events. Periods with more frequent storm flooding occurred 980–1050, 1150–1300, 1450–1550, 1820–1900 and 1950–2000 ce, which is largely consistent with a positive North Atlantic Oscillation mode. The Little Ice Age (1400–1850 ce) shows a gap of major sand layers suggesting a southward shift of storm tracks and a seasonal variance with more storm floods in spring and autumn. Warmer phases shifted winter storm tracks towards the north-east Atlantic, indicating a possible trend for future storm-track changes and increased storm flooding in the northern North Sea region.
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RBINS Staff Publications 2023
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Issid planthoppers from Bach Ma and Phong Dien in Central Vietnam. I. Tribe Parahiraciini (Hemiptera: Fulgoromorpha: Issidae)
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The late Holocene tsunami in the Shetland Islands (UK) identified in Loch Flugarth, north Mainland
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Tsunami deposits around the North Sea basin are needed to assess the long-term hazard of tsunamis. Here, we present sedimentary evidence of the youngest tsunami on the Shetland Islands from Loch Flugarth, a coastal lake on northern Mainland. Three gravity cores show organic-rich background sedimentation with many sub-centimetre-scale sand layers, reflecting recurring storm overwash and a sediment source limited to the active beach and uppermost subtidal zone. A basal 13-cm-thick sand layer, dated to 426–787 cal. a CE based on 14C, 137Cs and Bayesian age–depth modelling, was found in all cores. High-resolution grain-size analysis identified four normally graded or massive sublayers with inversely graded traction carpets at the base of two sublayers. A thin organic-rich ‘mud’ drape and a ‘mud’ cap cover the two uppermost sublayers, which also contain small rip-up clasts. Grain-size distributions show a difference between the basal sand layer and the coarser and better sorted storm layers above. Multivariate statistical analysis of X-ray fluorescence core scanning data also distinguishes both sand units: Zr, Fe and Ti dominate the thick basal sand, while the thin storm layers are high in K and Si. Enriched Zr and Ti in the basal sand layer, in combination with increased magnetic susceptibility, may be related to higher heavy mineral content reflecting an additional marine sediment source below the storm-wave base that is activated by a tsunami. Based on reinterpretation of chronological data from two different published sites and the chronostratigraphy of the present study, the tsunami seems to date to c. 1400 cal. a BP. Although the source of the tsunami remains unclear, the lack of evidence for this event outside of the Shetland Islands suggests that it had a local source and was smaller than the older Storegga tsunami (8.15 cal. ka BP), which affected most of the North Sea basin.
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An updated subjective global checklist of the extant non-marine Ostracoda (Crustacea)
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We present an updated global checklist of extant non-marine Ostracoda, covering taxonomic changes in the published literature up to 31st December 2023. The checklist is subjective, as apart from published taxonomic changes, also some additional alterations are proposed, including ten candonid tribes which are upgraded to subfamilies, six new combinations, one new name, five synonymies and one new taxonomic placement. The checklist presently includes 2420 accepted species in 295 genera,as well as 84 uncertain species that are too poorly described to be recognisable. We also provide the totals of species numbers for each taxonomic rank, from genera up to order, and numbers of species and endemic species in each of the world’s major zoogeographical regions.
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A New Species of Elpidium (Crustacea, Ostracoda) from Bromeliad and Non-bromeliad Phytotelmata in the Northeast of Argentina
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A new species of the ostracod genus Elpidium (Timiriaseviinae), a group almost exclusively known from Neotropical bromeliad phytotelmata, is here described and illustrated from the northeast of Argentina. Elpidium chacoense n. sp. represents the first record of the genus in this country and brings the total of described Elpidium species to 19. In view of the recently increased knowledge on the distribution of the species in this Neotropical genus, we discuss potential drivers of speciation that might have led to the high (endemic) diversity of the group: allopatry in bromeliad islands, sexual selection and putative co-evolution between ostracod and bromeliad species. We also point out the biogeographical relevance of the present records, which are amongst the most southern of the genus. Finally, also the fact that species of Elpidium can now also be found in non-bromeliad phytotelmata is of relevance.
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Accounting for interspecies and intraspecies variation in swimming performance for fish passage solutions
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Across the globe, there are millions of in-stream structures that fragment the world'’s river networks, acting as barriers that can impede the movements of fish. Designing effective solutions to accommodate fish communities requires information about the swimming abilities and behaviours of all species. This should account for different swimming modes, abilities, behaviours, and niches. We investigated the swimming speeds of nine migratory New Zealand species to assess both inter- and intraspecies variation. We then calculated maximum traversable speeds for culverts of a given length, based on the endurance abilities of our lowest performing species (Galaxias maculatus). Our findings reveal significant inter- and intraspecies variation in swimming speeds. Among the species studied, Galaxias brevipinnis, Galaxias argenteus, and Galaxias postvectis were the strongest swimmers. In contrast, Galaxias maculatus was one of the weakest swimmers. Body length positively correlated with Umax indicating that fish passage barriers select against the weakest swimming species, as well as smaller individuals within a species. Maximum water speeds in a culvert must be lower than 0.3 m s−-1, the previously assumed standard rule-of-thumb for New Zealand, to provide adequate passage for a high proportion of a weak-swimming indicator species (Galaxias maculatus). Synthesis and applications: . Previous maximum traversable water speeds for fish passage designs have been based on average swimming ability, but this approach only enables fish that are better than the average swimmers of their species to overcome barriers. This study highlights the importance of evidence-based designs for successful fish passage solutions to account for the ability of all fish. By considering differences between and within species, rather than assuming a “‘one-size-fits-all” ’ approach we can develop more effective passage solutions that better preserve fish communities.
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