Morphology and distribution of Navicula schmassmannii and its transfer to genus Humidophila

A small diatom with a peculiar shape is often identified as Navicula schmassmannii in samples collected from alpine lakes and the Arctic region. Due to its characteristic outline, it is relatively well-identifiable, but scanning electron microscope (SEM) confirmation is essential for proving species identity. This species likely has a palaeoecological indicator value of warming climate in mountain lakes, although it is generally a minor component of the diatom assemblages. Here we re-investigate its type material to clarify its identity and taxonomic position. We provide an emended description based on SEM observation, including new information on girdle morphology. Furthermore, another population of N. schmassmannii was studied. Detailed morphological observations using light microscope (LM) and SEM were done on specimens from a sediment core obtained from Lake Brazi in the Southern Carpathian Mountains. Late-glacial and early Holocene populations of the diatom resembling N. schmassmannii showed high morphological variability in comparison with the type material. On the basis of details of type material and the different morphotypes from Lake Brazi, the transfer of N. schmassmannii Hustedt to the genus Humidophila is proposed as H. schmassmannii (Hustedt) Buczkó et Wojtal

Nonreceding hare lines: genetic continuity since the Late Pleistocene in European mountain hares (Lepus timidus)

Throughout time, climate changes have caused substantial rearrangements of habitats which have alternately promoted and disfavoured different types of taxa. At first glance, the mountain hare (Lepus timidus) shows the typical hallmarks of a cold-adapted species that has retreated to refugia since the onset of the current Holocene interglacial. In contrary to expectations, however, the species has a high contemporary genetic diversity with no clear differentiation between geographically isolated populations. In order to clarify the phylogeographic history of European mountain hares, we here analysed ancient DNA from the glacial populations that inhabited the previous midlatitude European tundra region. Our results reveal that the Ice Age hares had similar levels of genetic variation and lack of geographic structure as observed today, and the ancient samples were intermingled with modern individuals throughout the reconstructed evolutionary tree. This suggest a temporal genetic continuity in Europe, where the mountain hares were able to keep pace with the rapid changes at the last glacial/interglacial transition, and successfully track their shifting habitat to northern and alpine regions. Further, the temporal demographic analyses showed that the species’ population size in Europe appear to have been tightly linked with palaeoclimatic fluctuations, with increases and declines occurring during periods of global cooling and warming, respectively. Taken together, our results suggest that neither habitat shifts nor demographic fluctuations have had any substantial impact on the genetic diversity of European mountain hares. This remarkable resilience, which contrasts to a majority of previously investigated cold-adapted species, is likely due to its generalist nature which makes it less vulnerable to environmental changes

Centric diatoms of large rivers and tributaries in Hungary: morphology and biogeographic distribution

Centric diatoms of 107 different Hungarian running waters were investigated. Among them the largest was the River Danube, from which more than one hundred plankton samples were analysed by scanning electron microscopy (SEM). Only one sample was analysed from creeks, which were the smallest running waters analysed in this study. There were also channels with slow currents flowing out of rivers or connecting different rivers.In total, 41 centric taxa belonging to 11 genera were found during this study. The average number of taxa found in a single watercourse was 7, the maximum 40 and the minimum 1. Cyclotella meneghiniana was the most frequently encountered species (present in 60% ofsites). Twelve taxa were found in more than 20% of sites, 7 taxa between 5–10% and 6 taxa only in one site

Morphometric variation of reindeer remains (Rangifer tarandus Linnaeus, 1758) from Late Pleistocene cave localities in Poland

The paper deals with the morphometric analysis of remains of the reindeer Rangifer tarandus Linnaeus, 1758 from 20 Late Pleistocene cave localities in Poland. In most of the localities, the species was the most abundant component of the large mammal fauna; the remains came from individuals, killed by predators, including man. The measurements of the remains were compared with those of reindeer from localities in Germany, Moldova, Ukraine and Russia. The measurements of the reindeer from Poland were intermediate between the smaller and more slender reindeer from north-western Europe and the larger reindeer from southern and eastern Europe; the antlers from the localities studied mainly represented the tundra form of Rangifer tarandus. The forest form of the species was represented by a few antlers. With respect to the ages of individuals, the reindeer from the Polish sites belonged to the age classes of under 2 years, 5–6 years and 6–7 years

Microstructures and rheology of a calcite-shale thrust fault

A thin (similar to 2 cm) layer of extensively sheared fault rock decorates the similar to 15 km displacement Copper Creek thrust at an exposure near Knoxville, TN (USA). In these ultrafine-grained (\u3c0.3 mu m) fault rocks, interpenetrating calcite grains form an interconnected network around shale clasts. One cm below the fault rock layer, sedimentary laminations in non-penetratively deformed footwall shale are cut by calcite veins, small faults, and stylolites. A 350 mu m thick calcite vein separates the fault rocks and footwall shale. The vein is composed of layers of (1) coarse calcite grains (\u3e5 mu m) that exhibit a lattice preferred orientation (LPO) with pores at twin twin and twin-grain boundary intersections, and (2) ultrafinegrained (0.3 mu m) calcite that exhibits interpenetrating grain boundaries, four-grain junctions and lacks a LPO. Coarse calcite layers crosscut ultrafine-grained layers indicating intermittent vein formation during shearing. Calcite in the fault rock layer is derived from vein calcite and grain-size reduction of calcite took place by plasticity-induced fracture. The ultrafine-grained calcite deformed primarily by diffusion-accommodated grain boundary sliding and formed an interconnected network around shale clasts within the shear zone. The interconnected network of ultrafine-grained calcite indicates that calcite, not shale, was the weak phase in this fault zone. (C) 2014 Elsevier Ltd. All rights reserved

Particle d15N values of amino acids from EXPORTS cruises SR1812 on R/V Sally Ride and RR1813 on R/V Roger Revelle in August to September 2018

Dataset: Particle d15N values of amino acidsThis dataset includes d15N values of individual amino acids from size-fractionated and sinking particles collected on the EXPORTS cruises (SR1812 on R/V Sally Ride and RR1813 R/V Roger Revelle) in August to September 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/880041NSF Division of Ocean Sciences (NSF OCE) OCE-183001

Diversity of the genus Genkalia (Bacillariophyta) in boreal and mountain lakes - taxonomy, distribution and ecology.

Genkalia digitulus (Hustedt) Lange–Bert. et Kulikovskiy (≡ Navicula digitulus Hustedt) is recorded from several lakes in the northern Europe and from high altitude lakes all over Europe. Wide distribution and characteristic autecology of this species allow its use as a bioindicator of pH changes and reliable marker of environmental reconstruction. A comparison of specimens found in lakes from the Carpathian and Balkan Mountains with the type material of Genkalia digitulus (Hustedt) Lange–Bert. et Kulikovskiy resulted in description of a new species – G. boreoalpina Wojtal, C.E. Wetzel, Ector, Ognjanova–Rumenova et Buczkó. Genkalia boreoalpina is characterised by valve outline, size and parallel striae throughout most of the valve. The separation was based on light and scanning electron microscopy. Genkalia boreoalpina was the most common diatom of the genus from high mountain lakes of slightly acidic waters with a very low mineral content. The third species, Navicula subprocera Hustedt, was found in the Lake Câlcescu (Parâng Mountains) in alkaline waters and in a mountain fen in Herzegovina. The nomenclatorial combination to Genkalia was made for this species. Previously published data suggest there is a much larger diversity of species in the genus Genkalia and the cosmopolitan distribution of this group is mostly presented at the genus level