Revision of the taxonomic position of Pseudocypretta Klie, 1932 (Ostracoda: Cyprididae), with a redescription of P. maculata Klie, 1932

Pseudocypretta maculataKlie, 1932, type species of the genus, is redescribed based on new material from Thailand. The main diagnostic features of the species are the presence of marginal septa, presence of Wouters organ on the first antenna, strongly serrated claw G2 of the second antenna (A2), small β seta on the mandibular palp, elongated terminal segment of the maxillular palp, smooth and large bristles on the third endite of the maxillula, undivided penultimate segment of the second thoracopod (T2), absence of d1 seta on the T2, completely separated terminal segment of the third thoracopod, absence of a pincer organ, and reduced caudal ramus with a triangular base. The taxonomic position of PseudocyprettaKlie, 1932 is also revised. Based on molecular analysis using the cytochrome c oxidase subunit I (COI), Pseudocypretta appears closer to Cypridopsinae Kaufmann, 1900 than to Cyprettinae Hartmann, 1971. This result is congruent with morphological evidence and, among other cypridopsine genera, Pseudocypretta shows highest similarity with CyprettadopsisSavatenalinton, 2020 given its reduced caudal ramus, the strongly serrated claw G2 of the A2, absence of pincer organ, and presence of marginal septa. Pseudocypretta is therefore allocated to the tribe Cyprettadopsini Savatenalinton, 2020

Youngest Iberian Holocene volcanic eruptions and paleoenvironmental evolution of a barrier-paleolake in the Garrotxa Volcanic Field (NE Spain)

Volcanic eruptions are key drivers of climate variability, with complex environmental consequences at regional and local scales that are rarely documented in high-resolution sedimentary records. In this work we present the results of a 15 m long paleolake core (Pla de les Preses core, Vall d’en Bas, Girona, NE Spain) covering the Late Pleistocene-Holocene transition. Multiproxy analyses including chronostratigraphy, sedimentology, micropalaeontology and geochemistry are used to reconstruct the paleoenvironmental framework of the Late Pleistocene-Holocene transition and to detect the youngest Holocene volcanic eruptions in the Garrotxa Volcanic Field (GVF) and the Iberian Peninsula. The studied sedimentary record covers the last ca. 13.5 ka cal BP and was punctuated by several rapid climatic changes including the 9.3, 8.2 and 7.1 ka events, affecting the hydrological evolution of a barrier-lake formed due to the volcanic damming of the Fluvià river. Sedimentological and geochemical analyses unveil the environmental history of Vall d’en Bas valley; the formation of a lacustrine area within a fluvial environment around 13.5 ka cal BP and later a wetland phase between 9.3 and 8.2 ka cal BP. Abrupt sedimentary changes marking the onset and demise of the wetland phase were linked to hemispheric cooling and drying events (e.g. 9.3 and 8.2 ka cal BP), provoking a decline in the water table during these phases. In addition, 30 tephra layers are detected thorough the core, showing previously unknown intense volcanic activity from 13.5 to 8.3 ka cal BP in the GVF. In that sense, the Pla de les Preses sequence provides, for the first time, evidence for early Holocene volcanic activity in NE Iberia that should be taken into account in future tephra studies in the western Mediterranean realm

Artificial dam lakes as suitable habitats for exotic invertebrates: Ostracoda ecology and distribution in reservoirs of the Eastern Iberian Peninsula

Reservoirs are the most common deep lakes in Spain, as a consequence of water needs and dry climate. Although these aquatic systems can play an important ecological role in such an area with few large natural lakes, they can also provide new habitats for exotic species, which can colonize ecosystems that native species have not explored yet. Here we present our results for a biannual survey of the ostracod fauna from 24 reservoirs in Xúquer River basin. We check which variables affect ostracod presence, test for differences between winter and summer assemblages, and compare our data with previous available ostracod records from the same river drainage network. Our results reveal that ostracod presence is positively related to high diversity of the invertebrate community and reservoir volume, and negatively with phosphorus concentration. Among the 22 species found, it is noteworthy the first Iberian record of Ilyocypris getica and the second European record of Candonocypris novaezelandiae. Ostracod assemblages significantly vary between summer and winter, and strong differences are found between ostracod communities of reservoirs and those from their connected rivers. Remarkably higher frequency of exotic species in the reservoirs confirms previous findings about the facilitation that artificial ecosystems confer to aquatic invasions

Artificial dam lakes as suitable habitats for exotic invertebrates: Ostracoda ecology and distribution in reservoirs of the Eastern Iberian Peninsula

Reservoirs are the most common deep lakes in Spain, as a consequence of water needs and dry climate. Although these aquatic systems can play an important ecological role in such an area with few large natural lakes, they can also provide new habitats for exotic species, which can colonize ecosystems that native species have not explored yet. Here we present our results for a biannual survey of the ostracod fauna from 24 reservoirs in Xúquer River basin. We check which variables affect ostracod presence, test for differences between winter and summer assemblages, and compare our data with previous available ostracod records from the same river drainage network. Our results reveal that ostracod presence is positively related to high diversity of the invertebrate community and reservoir volume, and negatively with phosphorus concentration. Among the 22 species found, it is noteworthy the first Iberian record of Ilyocypris getica and the second European record of Candonocypris novaezelandiae. Ostracod assemblages significantly vary between summer and winter, and strong differences are found between ostracod communities of reservoirs and those from their connected rivers. Remarkably higher frequency of exotic species in the reservoirs confirms previous findings about the facilitation that artificial ecosystems confer to aquatic invasions

Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs of Eucypris virens (Crustacea, Ostracoda)

1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long-term persistence completely relies on the build-up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all-female Eucypris virens populations. Hatching time and success was compared between control eggs and eggs exposed to one of seven ecologically relevant stressors: digestive enzymes, high salinity, deep freezing, hydration, UV-B radiation, hypoxia, and insecticide treatment. 3. None of the stressors reduced statistically the viability of either sexual or asexual eggs. When compared with the reproductive mode specific controls, exposure to UVB radiation had a mild impact on the survival of sexual and asexual eggs (-16.8% and -22.4%, respectively), but this was only significant for asexual eggs. These results point to an extreme tolerance of E. virens resting eggs, and have important implications for the ecology and evolution of the species. 4. The timing of hatching was not affected by the stress treatment, except for UV-B radiation. A marginally significant delay in hatching response was observed for UV-B radiated eggs when compared to the overall mean, but this treatment effect was absent when compared with the reproductive mode specific controls. 5. The populations with males produced eggs that hatched on average earlier (-1.5 days at 17˚C) and were more successful (+26%) than asexual eggs. Due to the limited number of populations and the population-specific origin and age of the eggs, the possibility due to differences in age and origin of the resting eggs, or to variations in local conditions, cannot be ruled out

Are aquatic assemblages from small water bodies more stochastic in dryer climates? An analysis of ostracod spring metacommunities

Metacommunity ecology describes community organisation considering both environmental and spatial processes. We tested the relative importance of environmental and spatial factors on spring ostracod assemblages from four European regions characterised by different climatic conditions (e.g. aridity). Pure and shared effects of environment and space were calculated using redundancy analysis and variation partitioning. Both environmental and spatial variables significantly explain assemblage variation, although with different relevance among areas. The amount of variation explained by environmental factors decreased with increasing climate aridity. The reduced size of spring habitats makes them prone to drying events, which are more frequent in dryer climates. Frequent disturbances may lead to local extinctions followed by colonisations from nearby sites, in a source–sink dynamics. Early recolonisation leads to random assemblages and reduces the match between organisms and environmental conditions. As a consequence, a low amount of community variation can be explained by environmental variables. Conversely, the settled communities from wetter climates best fit the ecological characteristics of sites, and deterministic processes, such as species sorting, dominate the assemblages. In conclusion, in the studied regions, ostracod communities from small water bodies of dryer climates seem to be mainly driven by stochastic dynamics when compared to more continental areas

Mate recognition as a reproductive barrier in sexual and parthenogenetic Eucypris virens (Crustacea, Ostracoda)

Mate selection is one of the motors of evolution and of particular importance in the case of organisms in which sexual and parthenogenetic populations coexist. Sexual populations of the ostracod species complex Eucypris virens are often mixed with parthenogenetic ones. A powerful mate selection mechanism must exist to avoid time, energy and sperm loss, for the maintenance and success of sexual reproduction in these mixed populations. There are four types of E. virens individuals: males (diploid), sexual females (diploid) and asexual females (parthenogenetic and either di- or triploid). From one parthenogenetic population and two populations with males of E. virens, we sampled early stage juveniles, and reared them to adulthood in isolation. We combined three virgin ostracods, one male and two females, these latter of contrasting reproductive mode (sexual versus asexual) and origin (allopatric versus sympatric to the males). A posteriori molecular analyses further allowed identification of the mitochondrial clade and ploidy level of the individuals. Strong mate preferences were detected: sexual encounters occurred almost exclusively between males and sexual females and those involving asexual females (either di- or triploid) occurred rarely. The clear recognition of sexual individuals among each other implies that the presence of parthenogens does not greatly disturb the reproductive process in the sexual population. Moreover, this behaviour might play a role in the emergence and cohesiveness of cryptic species within E. virens. Although rare in small populations and at short timescales, copulations between males and asexual females support the hypothesis of hybrid origin for polyploidy