Overwintering of terrestrial Arctic arthropods: the fauna of Svalbard now and in the future

There are over 500 species of arthropods recorded from Svalbard. These animals overwinter either within the soil or on the ground surface, and have to tolerate an environment where the ground is frozen for over 9 months each year. Three cold-tolerance strategies have been described from Svalbard invertebrates: freeze avoidance, freeze tolerance and desiccation. Once in a cold-tolerant state the animals can be extremely cold tolerant in terms of both minimum exposure temperature and period of exposure. How the overwintering capabilities of these animals will be affected by climate changes during the next 100 years, as predicted by climate models, is not yet known. Four principle factors with an impact on overwintering of the terrestrial arthropod fauna are outlined here: (1) warmer winter temperatures, with an increased frequency of extreme events such as freeze–thaw cycles and surface icing; (2) changes in snow fall and snow lie; (3) pollutant load; and (4) dispersal of invertebrates to Svalbard. Finally, areas where further research is required are highlighted: including the development of controlled multi-season field experiments; effect of freeze–thaw cycles; changes in thickness and distribution of snow lie, with the subsequent effects on duration of the summer period; chill susceptibility of soil arthropods; assessing potential colonizing species and the likelihood of these species becoming established; assessing the effect of gene flow from surrounding populations; interactions between pollution and cold tolerance; anoxia stress; and the genetics of cold tolerance.     

Dimorphism of Bivalved Arthropod Branchiocaris? Yunnanensis from the Early Cambrian Chengjiang Biota, South China

The bivalved arthropod Branchiocaris? yunnanensis Hou, 1987 is redescribed on the basis of new fossil material from the early Cambrian Chengjiang biota, South China. In total, 81 specimens have been examined. The carapace comprises two identical valves, each valve are sub-circular in outline, ranging from 24 mm to 58 mm in length, and from 15 mm to 46 mm in height. The dorsal margin is straight and bears two short cardinal spines. The valve surface is either smooth or ornamented with polygonal reticular structures, which may result from different preservation conditions. Two morphotypes have been recognized based on the presence or absence of a subdorsal swelling of the valve, which is convex dorsolaterally and extends beyond the dorsal margin when it appears. Statistic and ontogenetic analyses show both morphotypes grow isometrically and have the same growth trajectory. Therefore, the two morphotypes are interpreted as dimorphism within the same species. Our results are helpful for investigating the taxonomy and ontogeny of arthropod fossils and suggest that dimorphism might be fairly common in these early arthropods.     

Testing use of mitochondrial COI sequences for the identification and phylogenetic analysis of New Zealand caddisflies (Trichoptera)

We tested the hypothesis that cytochrome c oxidase subunit 1 (COI) sequences would successfully discriminate recognised species of New Zealand caddisflies. We further examined whether phylogenetic analyses, based on the COI locus, could recover currently recognised superfamilies and suborders. COI sequences were obtained from 105 individuals representing 61 species and all 16 families of Trichoptera known from New Zealand. No sequence sharing was observed between members of different species, and congeneric species showed from 2.3 to 19.5% divergence. Sequence divergence among members of a species was typically low (mean = 0.7%; range 0.0–8.5%), but two species showed intraspecific divergences in excess of 2%. Phylogenetic reconstructions based on COI were largely congruent with previous conclusions based on morphology, although the sequence data did not support placement of the purse‐cased caddisflies (Hydroptilidae) within the uncased caddisflies, and, in particular, the Rhyacophiloidea. We conclude that sequence variation in the COI gene locus is an effective tool for the identification of New Zealand caddisfly species, and can provide preliminary phylogenetic inferences. Further research is needed to ascertain the significance of the few instances of high intra‐specific divergence and to determine if any instances of sequence sharing will be detected with larger sample sizes.     

A new Plattenkalk Konservat Lagerstätte in the Upper Cretaceous of Gara Sbaa, south-eastern Morocco

Laminated, dolomitised marine limestones within a transgressive fluvio-lagoonal-carbonate platform sequence at Gara Sbaa in the Kem Kem region of south eastern Morocco yield well preserved marine fishes and crustaceans. A rarer terrestrial component includes delicate fern fronds, insects and a lizard. Sedimentological structures and stratigraphic context indicate initial shallow waters with in a carbonate lagoon with benthic microbial mats followed by deepening. High precision dating has yet to be accomplished, but a Late Cenomanian or Early Turonian age is indicated on the basis of faunal and sequence-stratigraphic considerations. The fish assemblage has affinities with mid-Cretaceous ichthyofaunas in South America and Lebanon, including taxa in common at generic level.     

Two New Fossil Sawflies (Hymenoptera, Xyelidae, Xyelinae) from the Middle Jurassic of China

Two new genera with two new species of sawflies, Cathayxyela extensa gen. et sp. nov. and Aequixyela immensa gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation of southeastern Inner Mongolia, China, are assigned to the subfamily Xyelinae （Hymenoptera, Xyelidae）. Cathayxyela gen. nov. can be distinguished by the third antennal article longer than the head; mesoprescutum and mesoscutellum nearly equal in length; the forewing with Sc meeting C before the junction of 1-M and 1- Rs; a weak and narrow pterostigma; and 3-Cu at least 1.5 times longer than the lm-cu. Aequixyela gen. nov. is characterized by the third antennal article nearly as long as the head; the forewing with Rs＋M approximately equal to 2-Rs in length; 2m-cu inclined toward the wing base and nearly reaching the middle of cell 3rm; lm-cu as long as the 2-Cu and 3-Cu; and the cell 2cua of regular hexagonal shape.     

Sequence and scale of changes in the terrestrial biota during the Cretaceous (based on materials from fossil resins)

Сomparative analysis of arthropod assemblages found in Cretaceous fossil resins is provided. Arthropod-bearing Cretaceous resin sites are reviewed, and a list of arthropod records (identified to the family level) published up to 2015 is provided. Also, new records of mites, and new arthropod records from the Siberian resins are given. An efficient method for extracting amber from loose sediments in situations of limited infrastructure but easy access to water is described as well.The sequence of arthropod assemblages in Cretaceous resins according to their evolutionary aspect does not match their geological sequence. This can be only partly explained by taphonomic constraints and inadequacy of the material: there is a deeper difference between somewhat contemporary assemblages than was characteristic of Permian assemblages studied in a similar way in previous studies. Our results confirm the earlier hypothesis that the Palaeozoic–Mesozoic biotic crisis was not so much a mass extinction as a biotic reorganisation that opened the way to diversification. These results might indicate a peculiar feature of the immediate effects of such reorganisations, namely that Mesozoic–Cenozoic communities became differentiated in their compositions much deeper than Palaeozoic ones (i.e., that their constituent groups acquired the ability to evolve much deeper changes while adapting to the ecological specifics of their environments). A transformation of organisms and/or their communities took place, comparable in scope to the rise of skeletal fauna in the Cambrian. The difference between these two transformations is that the later one resulted not from a particular adaptation (the skeleton) but from the ability to specialize more deeply than was possible in the Palaeozoic.     

Two New“Notostracans”,Chenops gen.nov.and Jeholops gen.nov. (Crustacea:Branchiopoda:?Notostraca) from the Yixian Formation,Northeastern China

<正>The Early Cretaceous Jehol biota of northeastern China contains a diverse group of notostracans, including two genera,Chenops and Jeholops,described here.Chenops is characterized by a combination of an ovate carapace,narrow anal plate,equant distal endites and endopod on the anterior thoracic limbs.In addition to the new species,Chenops yixianensis,the genus also provisionally includes Prolepidurus oblongus Oleynikov, 1968.Jeholops,however,is monotypic,represented by the new species Jeholops hongi.It is characterized by a combination of kazacharthran and notostracan features unique to this taxon.Both new genera are provisionally placed in the taxon Notostraca.More detailed work exploring the morphology of exceptionally-preserved branchiopod crustaceans is needed.The difficulties in placing fossil notostracans into a phylogenetic framework are discussed.