Search results for "Systematic"
showing 10 items of 7608 documents
Taxonomic revision of Riella subgenus Trabutiella (Riellaceae, Sphaerocarpales)
2014
The genus Riella (Riellaceae, Sphaerocarpales) includes some 24 species of thalloid aquatic liverworts with unique morphological and ecological features among hepatics. These include the development of sporophytes enclosed within involucres and growing submerged in seasonal fresh or brackish water ponds. Riella subgenus Trabutiella includes species with winged involucres. Seven taxa have been described, however, four to five taxa have been recognized at a time depending on authors. In this study we have conducted a morphological revision of the species of this subgenus, based on 59 traits measured under light and Scanning Electron Microscopy analyses and that were the subject of statistical…
Variability in δ13C values between individual Daphnia ephippia: Implications for palaeo-studies
2018
The stable carbon isotope ratio (δ13 C value) of Daphnia spp. resting egg shells (ephippia) provides information on past changes in Daphnia diet. Measurements are typically performed on samples of _20 ephippia, which obscures the range of values associated with individual ephippia. Using a recently developed laser ablation-based technique, we perform multiple δ13 C analyses on individual ephippia, which show a high degree of reproducibility (standard deviations 0.1e0.5‰). We further measured δ13 C values of 13 ephippia from surface sediments of three Swiss lakes. In the well-oxygenated lake with low methane concentrations, δ13 C values are close to values typical for algae (_31.4‰) and the …
Ultraviolet radiation exposure of a high arctic lake in Svalbard during the Holocene
2014
Long-term fluctuations in lake-water optical properties were examined using a Holocene sediment sequence and multi-proxy palaeolimnological approach in Lake Einstaken, Nordaustlandet, Svalbard. UV-absorbance of sedimentary cladoceran remains provided information on underwater UV exposure and changes in lake-catchment coupling processes were inferred from sediment geochemistry. In addition, aquatic community succession was used as an indicator for lake-water bio-optical properties and a Holocene record of sun activity (sunspots) was utilized to evaluate long-term solar forcing. The results indicated that the UV-absorbance of cladoceran remains was highest (i.e. maximum UV-induced pigmentatio…
Climate signal age effects in boreal tree-rings: Lessons to be learned for paleoclimatic reconstructions
2016
Abstract Age-related alternation in the sensitivity of tree-ring width (TRW) to climate variability has been reported for different forest species and environments. The resulting growth-climate response patterns are, however, often inconsistent and similar assessments using maximum latewood density (MXD) are still missing. Here, we analyze climate signal age effects (CSAE, age-related changes in the climate sensitivity of tree growth) in a newly aggregated network of 692 Pinus sylvestris L. TRW and MXD series from northern Fennoscandia. Although summer temperature sensitivity of TRW ( r All = 0.48) ranges below that of MXD ( r All = 0.76), it declines for both parameters as cambial age in…
Small but smart: the interaction between environmental cues and internal state modulates host-patch exploitation in a parasitic wasp
2007
International audience; The reproductive success of insect parasitoids depends on two activities, searching for hosts to obtain immediate fitness rewards (offspring) and searching for food to extend life span and enhance future reproductive opportunities. Models suggest that to deal with this trade-off and to cope with the variability of the resources they depend on, parasitoids should simultaneously integrate information originating from three distinct sources: host and food availabilities in the environment (environmental information) and the metabolic reserves of the parasitoid (internal information). We tested whether, in the parasitic wasp Venturia canescens, these three types of infor…
Rediscovery and identity of Pumilomyia protrahenda De Stefani (Diptera, Cecidomyiidae) in Sicily with redescription and reassessment of its taxonomic…
2016
Abstract A population of the gall midge Pumilomyia protrahenda De Stefani, 1919 causing galls on Artemisia arborescens (Asteraceae) was discovered near Palermo (Sicily) in 2008. This species had not been found since 1918. Detailed study of morphological characters of adults, larvae and pupae revealed that Pumilomyia protrahenda belongs to the genus Rhopalomyia Rübsaamen, 1892, tribe Rhopalomyiini. The monotypic genus Pumilomyia De Stefani, 1919 is therefore synonymized under Rhopalomyia Rübsaamen, 1892. Rhopalomyia protrahenda comb. n. is redescribed, with important morphological characters illustrated. Adults have one-segmented palpi, antennae with 12–13 short flagellomeres and long legs w…
Diplurans of subsurface terrestrial habitats in the Iberian Peninsula, with a new species description (Diplura: Campodeidae)
2017
Although Iberian subsurface terrestrial habitats have been sampled for a half century, they remain poorly known. During the last five years much more sampling of these subsurface habitats has been made, mainly in scree slopes (also called colluvial Mesovoid Shallow Substratum habitats, MSS) but also in alluvial debris of temporal watercourses (alluvial MSS). In our study, diplurans, a basal hexapod group, were extracted from two hundred traps installed in 69 locations in the mountain ranges of six different regions of the Iberian Peninsula, from north to south: Cantabrian, Pyrenees, Iberic System, Central System, Prebaetic and Penibaetic Mountains. A total of 1251 specimens in fifteen diplu…
Standardised spider (Arachnida, Araneae) inventory of Kilpisjarvi, Finland
2020
Abstract Background A spider taxonomy and ecology field course was organised in Kilpisjarvi Biological Station, northern Finland, in July 2019. During the course, four 50 × 50 m plots in mountain birch forest habitat were sampled following a standardised protocol. In addition to teaching and learning about spider identification, behaviour, ecology and sampling, the main aim of the course was to collect comparable data from the Kilpisjarvi area as part of a global project, with the purpose of uncovering global spider diversity patterns. New information A total of 2613 spiders were collected, of which 892 (34%) were adults. Due to uncertainty of juvenile identification, only adults are includ…
The Leiobunum rupestre species group: resolving the taxonomy of four widespread European taxa (Opiliones: Sclerosomatidae)
2016
Within the central European opilionid fauna the widely used species names Leiobunum rupestre Herbst, 1799 and Leiobunum tisciae Avram, 1968 pose taxonomic and distributional problems. In addition, Nelima apenninica Martens, 1969 is close to L. tisciae in terms of external and genital morphology, but is specifically distinct. While coxal denticulation is largely lacking in N. apenninica, the validity of the genus Nelima Roewer, 1910 is questioned again. In addition, Leiobunum subalpinum Komposch, 1998, a recently described novelty from the eastern Alps, is closely related to L. rupestre. The four species are combined as the morphologically defined Leiobunum rupestre species group. Except for…
DNA barcoding the phyllosoma of Scyllarides squammosus (H. Milne Edwards, 1837) (Decapoda: Achelata: Scyllaridae)
2016
Scyllarides has the largest number of species with commercial importance within the Scyllaridae family. As for other achelate lobsters, however, little is known of the unique long-lived planktonic phyllosoma stages of any of these tropical and temperate species. Recently, a large and diverse collection of Scyllaridae phyllosoma, compiled from cruises along the Coral Sea and spanning several years, has been analysed. Molecular evidence from DNA-barcoding and phylogenetic analyses is provided here on the identity of S. squammosus phyllosoma larvae, including stages that were previously undescribed or poorly known. As a consequence, the growth and morphological changes that occur during the mi…