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Three new fossil species from Burmese amber are described, one clearly in family Calamoceratidae, the other two in the highly variable family Odontoceridae. The family Odontoceridae contains 18 disparate genera, but there are no good diagnostic characters, which makes it difficult to place fossil taxa in this family. We here offer a revised diagnosis for the family, highlighting the lack of good diagnostic characters, and the need to use sets of characters to place (extinct) taxa in this family. On this taxonomic basis we describe two new species in the hitherto monotypic fossil genus Palaeopsilotreta Wichard & Wang, 2017 (Odontoceridae), Palaeopsilotreta burmanica sp. nov. and P. cretacea sp. nov., redescribe the type species based on additional information, and describe features of the female, based on two specimens, one of which is embedded adjacent to a male identified as P. xiai. Males of Palaeopsilotreta bear bipectinate antennae; the antennae of the females are simple and filiform. Similarly, bipectinate antennae are present in the third species we describe, Bipectinata orientalis gen. et sp. nov., which otherwise lacks the character combinations associated with the Odontoceridae, but clearly can be assigned to the family Calamoceratidae.
A new species of the genus Mesobiotus is described from the Republic of South Africa using a traditional morphological approach (light and scanning electron microscopy) combined with molecular analysis (18S rRNA, 28S rRNA, ITS-2 and COI markers). Mesobiotus anastasiae sp. nov. differs from all known Mesobiotus species by having a unique combination of characters of the adult animals and the eggs. Adults of the new species have an oral cavity armature without elongate teeth in the second band, while the processes of the egg chorion have a basal collar and distinct rows of large pores. An updated key to the species of the genus Mesobiotus, including 66 of 70 currently described species, is given. An aquatic mite species from the Lobohalacarus weberi complex (freshwater Halacaridae) co-occurs with M. anastasiae sp. nov., suggesting that the newly described tardigrade inhabits constantly wet moss cushion habitats.
Freshwater sponges constitute an overlooked part of the freshwater fauna in Sweden and there has been no recent systematic survey. Hitherto three species have been found in Sweden: Spongilla lacustris (Linnaeus, 1759), Ephydatia fluviatilis (Linnaeus, 1759) and E. muelleri (Lieberkühn, 1856). Neighbouring countries (Norway, Denmark, Estonia) harbour at least one additional species. We present a study on freshwater sponge diversity and distribution in the southern half of Sweden. We hypothesized dispersal within catchments to be less constrained than between, even at shorter intercatchment than intracatchment distances, and, as result, genetic distances being greater between than within catchments. We collected and identified freshwater sponges from 34 sites, using morphological and molecular data (coxI, 28S rRNA gene). We can report the presence of Eunapius fragilis (Leidy, 1851) in Sweden for the first time, and that S. lacustris is the most abundant and widely distributed freshwater sponge in Sweden. Genetic markers were tested on S. lacustris individuals for a phylogeographic study. From the 47 primers (24 markers), one pair presented successful amplification and enough variation for phylogeographic studies – i56, an intron located in a conserved gene. Seven different variants were found in the sampling area, but no clear population structure was observed.
A documented checklist of the Crustacea (Stomatopoda, Decapoda) is provided for the southern Guianas region (sGuianas), a homogeneous ecoregion including Guyana, Suriname, French Guiana and the Brazilian State of Amapá. The history of crustacean collections undertaken there between 1759 and 2022 is summarized. In total, 529 species are listed. Biodiversity varies between countries: 165 species in Guyana; 317 in Suriname, 343 in French Guiana, and 315 in Brazil Amapá, as a direct result of different sampling efforts. There are 22 Stomatopoda and 507 Decapoda, ranked by numerical diversity as Brachyura (206), Caridea (113), Anomura (85), Dendrobranchiata (67) and others (36). The list is analyzed with the species classified by major biotopes, distinguishing those from freshwater, mangroves and estuaries, and frankly marine environments. Regional comparisons are made in the Western Atlantic showing that the sGuianas marine fauna is depauperate compared to that of other regions. This is explained by the influence of the Amazon River plume, carrying desalinated water and fine sediments, which leads to the reduction of coral reef formations in sGuianas. Only a few species of freshwater crabs (genera Kunziana and Microthelphusa) are endemic to the region. The pace of species discovery over the years indicates that the sGuianas fauna remains still imperfectly known and that probably more than 600 species are present in the region.
Macaronesia, with the exception of the Azores, is one of the few Palearctic provinces where basic taxonomic information on the freshwater copepods is still lacking. We redescribed Eucyclops azorensis, a cyclopid crustacean so far known only in the Azores, and report the occurrence of this species in Algeria and Madeira Island. Eucyclops azorensis was formerly considered to be a subspecies of E. agiloides (East Africa); therefore, the latter species is redescribed here as well based on type and non-type material. Morphological comparisons between E. azorensis, E. agiloides and other taxa (E. serrulatus and E. roseus), assumed to be closely related to our target species, support a closer relationship between E. azorensis and E. serrulatus (Palearctic) than between E. azorensis and E. agiloides (Afrotropical). The slight differences between E. azorensis and E. serrulatus in the surface ornamentation of the antennal coxobasis and intercoxal sclerites of legs 1 and 4 suggest a relatively young separation of these lineages. Eucyclops agiloides is morphologically close to E. roseus (temperate and subtropical Asia, southeastern Europe, East Africa). The numerous and clear-cut differences indicate a species rather than subspecies-level differentiation between E. agiloides and E. roseus, unlike what was formerly proposed in the taxonomic literature.
The studies of Cyclops O.F. Müller, 1776 have more than two centuries of tradition in Fenno- Scandinavia, yet, basic taxonomic questions remain unresolved and the limits of the distributional area are very poorly understood in the majority of the taxa (11+) occurring in the region. Based on the types and other materials we redescribe two species, C. lacustris G.O. Sars, 1863 and C. bohater Koźmiński, 1933, the latter being reported here for the first time from Fenno-Scandinavia; lectotypes of both species have been designated herein. Setulation characters of the antennal coxobasis- and maxillulary palp setae and P1 medial spine, as well as the spine formula of the terminal exopodal segments of the swimming legs (3433) in the adult female distinguish C. lacustris and C. bohater from their congeners. An identification key is provided to the Cyclops species of Fenno-Scandinavia, including information about both the female and male morphology. Although the limited material does not allow us to define the species range limits, our data nevertheless support a Northern European distribution in C. lacustris, and Northern and Central European distribution in C. bohater, while the records from the southern Palearctic need further verification.
An annotated checklist and bibliography of 197 species (representing 78 genera and 26 families) of non-marine polychaetes of the world is presented, including synonymies, information on ecology, distribution, habitat, and references to the taxonomic and biological literature. Over half (57%) of the checklist species are represented by just three families as follows: Nereididae (61 species including Namanereis, Namalycastis, Neanthes and Hediste), Aeolosomatidae (27 species, mostly Aeolosoma) and Sabellidae (24 species including Caobangia and Manayunkia). Other well-represented taxa are the epizoic histriobdel1id Stratiodrilus (11 species), the inland-sea-specialist ampharetid Hypania and related genera (5 species), and the freshwater-tolerant spionid Marenzelleria (5 species). One new combination is proposed for the nereidid Nereis tenuipalpa Pflugfelder, 1933, viz. Paraleonnates tenuipalpa n. comb.
There is increasing evidence that climate change will have a severe impact on species’ distributions by altering the climatic conditions within their present ranges. Especially species inhabiting stream ecosystems are expected to be strongly affected due to warming temperatures and changes in precipitation patterns. The aim of this thesis was to
investigate how distributions of aquatic insects, i.e., benthic stream macroinvertebrates would be impacted by warming climates. The methods comprised of an ensemble forecasting technique based on species distribution models (SDMs) and climate change scenarios of the Intergovernmental Panel on Climate Change of the year 2080. Future model projections were generated for a wide variety of species from a number of taxonomic orders for two spatial scales: a stream network within the lower mountain ranges of Germany, and the entire territory across Europe. In addition, the effect of the modelling technique on habitat suitability projections was investigated by modifying the choice of study area (continuous area vs. stream network) and the choice of predictors (standard vs. corrected set).
Projections of future habitat suitability showed that potential climate-change impacts would be dependent on species’ thermal preferences, and with a similar pattern for both spatial scales. Future habitat suitability was projected to remain for most or all of the modelled species, and species were projected to track their climatically suitable conditions by shifting uphill along the river continuum within the lower mountain ranges, and into a north-easterly direction across Europe. Cold-adapted headwater and high-latitude species were projected to lose suitable habitats, whereas gains would be expected for warm-adapted river and low-latitude species along the river continuum and across Europe, respectively. Additionally, habitat specialist species in terms of endemics of the Iberian Peninsula were identified as potential climate-change losers, highlighting their restricted habitat availability and therefore vulnerability to warming climates.
The main findings of this thesis underline the high susceptibility of stream macroinvertebrates to ongoing climate change, and give insights into patterns of possible consequences due to changes in species’ habitat suitability. Concerning the methodology, a clear recommendation can be given for future modelling approaches of stream macroinvertebrates by building models within a stream network and with a careful choice of environmental predictors, to reduce uncertainties and thus to improve model projections.