Ordered phylogenomic subsampling enables diagnosis of systematic errors in the placement of the enigmatic arachnid order Palpigradi.

The miniaturized arachnid order Palpigradi has ambiguous phylogenetic affinities owing to its odd combination of plesiomorphic and derived morphological traits. This lineage has never been sampled in phylogenomic datasets because of the small body size and fragility of most species, a sampling gap of immediate concern to recent disputes over arachnid monophyly. To redress this gap, we sampled a population of the cave-inhabiting species Eukoenenia spelaea from Slovakia and inferred its placement in the phylogeny of Chelicerata using dense phylogenomic matrices of up to 1450 loci, drawn from high-quality transcriptomic libraries and complete genomes. The complete matrix included exemplars of all extant orders of Chelicerata. Analyses of the complete matrix recovered palpigrades as the sister group of the long-branch order Parasitiformes (ticks) with high support. However, sequential deletion of long-branch taxa revealed that the position of palpigrades is prone to topological instability. Phylogenomic subsampling approaches that maximized taxon or dataset completeness recovered palpigrades as the sister group of camel spiders (Solifugae), with modest support. While this relationship is congruent with the location and architecture of the coxal glands, a long-forgotten character system that opens in the pedipalpal segments only in palpigrades and solifuges, we show that nodal support values in concatenated supermatrices can mask high levels of underlying topological conflict in the placement of the enigmatic Palpigradi.

Local- versus broad-scale environmental drivers of continental ß-diversity patterns in subterranean spider communities across Europe.

Macroecologists seek to identify drivers of community turnover (ß-diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale ß-diversity patterns remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of continental ß-diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35-70° latitude). Generalized dissimilarity modelling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of ß-diversity, with differential contributions of each factor according to the level of subterranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterranean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.

Type of fixative solution in pitfall traps as a decisive factor affecting community parameters of Collembola (Hexapoda) inhabiting superficial subterranean habitats.

Vertical distribution of collembolan communities along a depth gradient was studied at three forested karst scree slopes in the Western Carpathians, differing in topography, microclimate, soil-chemical parameters, and forest associations. Two different fixative solutions were used in subterranean pitfall traps. The activity and species richness of Collembola in the vertical scree profiles were significantly higher in traps filled with ethylene glycol than in those filled with formaldehyde at all three sites. Using traps filled with formaldehyde, both Collembola species numbers and activity positively correlated with the soil moisture and carbon content, while for ethylene glycol traps this relation was the same only for species numbers and carbon content. Ecological groups of Collembola showed a different response, distinguished by the level of association to subterranean habitats, to environmental factors and to the fixation liquid used in the subterranean traps. Eutroglophiles, the forms relatively well-adapted to subterranean habitats, were associated with depth exclusively when using ethylene glycol traps. This implies that ethylene glycol is a more suitable preservative in terms of species richness and activity of Collembola in deeper scree layers compared to traditionally used formaldehyde. Thus, the effect of environmental factors on diversity and vertical distribution of Collembola in scree habitats may be substantially superimposed by the type of fixation used in subterranean traps.

Testing the climatic variability hypothesis in edaphic and subterranean Collembola (Hexapoda).

The climatic variability hypothesis was applied to the thermal tolerance of edaphic and cave Collembola occupying contrasting environments. Collembola belonged to four categories - trogloxene, subtroglophile, eutroglophile and troglobiont - with a different degree of affinity to subterranean habitats. Altogether, specimens of 17 species were exposed to a one-hour laboratory survival test. The impact of temperature, species and species-temperature interaction on cold and heat survival was statistically significant. There was a decrease trend in cold and heat tolerance from trogloxenes, over subtroglophiles and eutroglophiles to troglobionts. It was shown that obligate cave species, restricted to climatic-stable cave conditions, retain a functional thermal resistance, i.e. the genetically determined ability to tolerate relatively broader temperature ranges. Our results outlined the direct relationship between the thermal tolerances of species and the size of their geographic distributions. It was also observed that cold resistance of Collembola decreased significantly with increasing species body length, indicating that body size plays an important role in temperature tolerances of arthropods inhabiting soil and subterranean habitats.

Biodiversity of a temperate karst landscape-ice cave collapse doline supports high α-diversity of the soil mesofauna.

Caves represent a specific environment with a special microclimate and fauna adapted to it. However, we have still a restricted knowledge on soil fauna communities in an environments with a marked microclimate gradient at the interface between cave and surface habitats. In the present study, we investigated the community patterns of dominant soil microarthropod group, oribatid mites, and their relationship to environmental factors across the microclimate gradient along a transect with seven study sites from cold and wet cave entrance zone to warm and drier deciduous forest. The cold and wet sites showed low oribatid abundances and a high spatial clustering of individuals in comparison to the warm sites. The oribatid mites showed significantly higher abundance and species richness at warm forest sites. Indicator species analysis indicated specific cold-tolerant species that dominated at cold sites of the gradient, but which were absent at the warmest sites. Variance analysis clarified that community composition at sites were significantly driven by environmental factors: temperature, soil moisture, pH and C/N ratio. The study underlines the importance of ice cave entrances as sources of high α-diversity of soil mesofauna and thus the conservation priority of these valuable habitats.

The impact of disturbance and ensuing forestry practices on Collembola in monitored stands of windthrown forest in the Tatra National Park (Slovakia).

Soil Collembola communities were investigated in spruce forest stands of the High Tatra Mts that had been heavily damaged by a windstorm in November 2004 and subsequently by a wildfire in July 2005. The study focused on the impact of these disturbances and forestry practices on collembolan community distribution and structure 4 years after the disturbance. Four different treatments were selected for this study: intact forest stands (REF), non-extracted windthrown stands (NEX), clear-cut windthrown stands (EXT) and burnt windthrown stands (FIR). From a total of 7,820 individuals, 72 species were identified. The highest total abundance mean was recorded in FIR stands followed by NEX and EXT stands and, surprisingly, the lowest in REF stands. The highest total species richness was observed in REF stands, followed by NEX stands and FIR stands and the lowest in EXT stands. In REF and NEX stands, the most abundant species were Folsomia penicula and Tetracanthella fjellbergi, while in heavily damaged stands, the most abundant was Anurophorus laricis. The ordination method used demonstrated a significant influence of treatment on the abundance of Collembola. ANOVA used confirmed significant differences for all dominant species between treatments. The present study shows the negative impact of windthrow on Collembola communities as reflected in decreased species richness and abundance. However, disturbance by fire caused a considerable increase in collembolan abundance 3 years after the event. Moreover, we show that clearing of windthrown spruce forests after a windstorm is less favourable for communities of soil collembolans and slows down the recovery process.

Four new troglobiotic species of the genus Megalothorax Willem, 1900 (Collembola: Neelipleona) from the Carpathian Mountains (Slovakia, Romania).

Four new species of Megalothorax Willem, 1900 are described and illustrated: M. tatrensis sp. nov., M. carpaticus sp. nov., M. hipmani sp. nov. from caves in Slovakia and M. draco sp. nov. from the Drǎcoaia Cave in western Romania. The species represent troglobiotic forms exhibiting different level of troglomorphy involving such features as larger body, elongated foot complex, antennae, mucro and body chaetae. The most pronounced troglomorphy is observed in M. hipmani sp. nov. and M. draco sp. nov. Species descriptions are completed with comparative tables of chaetotaxy of antennae and legs. Diagnostic table for all congeners and dichotomous identification key to the world species are provided. Distribution records of other Megalothorax species in Slovakia are added.

Globally invariant metabolism but density-diversity mismatch in springtails.

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.

A new European species of Ceratophysella (Collembola, Hypogastruridae) revealed by morphological data and DNA barcodes.

A new species, Ceratophysella stachi, from Denmark, Germany, Luxembourg, Norway, Poland, and Ukraine is described based on morphological data and DNA barcodes. It belongs to a small European group of species with type B chaetotaxy and strong tegumentary granulation with distinct fields of coarse granules: C. granulata Stach, 1949, C. lawrencei (Gisin, 1963), C. neomeridionalis (Nosek & Cervek, 1970), C. scotica (Carpenter & Evans, 1899), and C. silvatica Rusek, 1964. It differs from all of them in the chaetotaxy of lateral parts of thoracic terga II-III (setae m6 present and one additional seta outside lateral sensillum m7 present or absent) that is exceptional within the whole C. armata-group. Notes on closely related species C. granulata are also given.

The food web in a subterranean ecosystem is driven by intraguild predation.

Trophic interactions of cave arthropods have been understudied. We used molecular methods (NGS) to decipher the food web in the subterranean ecosystem of the Ardovská Cave (Western Carpathians, Slovakia). We collected five arthropod predators of the species Parasitus loricatus (gamasid mites), Eukoenenia spelaea (palpigrades), Quedius mesomelinus (beetles), and Porrhomma profundum and Centromerus cavernarum (both spiders) and prey belonging to several orders. Various arthropod orders were exploited as prey, and trophic interactions differed among the predators. Linear models were used to compare absolute and relative prey body sizes among the predators. Quedius exploited relatively small prey, while Eukoenenia and Parasitus fed on relatively large prey. Exploitation of eggs or cadavers is discussed. In contrast to previous studies, Eukoenenia was found to be carnivorous. A high proportion of intraguild predation was found in all predators. Intraspecific consumption (most likely cannibalism) was detected only in mites and beetles. Using Pianka's index, the highest trophic niche overlaps were found between Porrhomma and Parasitus and between Centromerus and Eukoenenia, while the lowest niche overlap was found between Parasitus and Quedius. Contrary to what we expected, the high availability of Diptera and Isopoda as a potential prey in the studied system was not corroborated. Our work demonstrates that intraguild diet plays an important role in predators occupying subterranean ecosystems.

Contribution to the genus Plutomurus Yosii (Collembola, Tomoceridae): notes on the morphology of Plutomurus carpaticus Rusek amp; Weiner and P. unidentatus (Börner).

In two European species of the genus Plutomurus Yosii, P. carpaticus Rusek Weiner and P. unidentatus (Börner), several diagnostic morphological characters are specified and illustrated: body chaetotaxy, number of internal spine-like chaetae on tibiotarsi and number of teeth on claw. The contribution is based on the study of type specimens of both species and specimens of other populations of their distribution ranges. The numerous specimens of the genus Plutomurus collected recently in the Western Carpathian caves are the most similar to P. carpaticus, but differ in macrochaetotaxy and may represent a new species. Three types of macrochaetae on thorax and abdomen of Plutomurus congeners from the Europe and Caucasus are defined. Identification key to European Plutomurus species is provided.

Subterranean Deuteraphorura Absolon, 1901, (Hexapoda, Collembola) of the Western Carpathians - Troglomorphy at the northern distributional limit in Europe.

An integrative approach employing molecular, morphological and geographical data were applied to species delimitation among Deuteraphorura congeners occupying caves of the Western Carpathian Mts. A new species of Deuteraphorura from the Western Carpathians is described. D. muranensis sp. nov. belongs among species with 4 pso at the hind margin of the head and possesses highly troglomorphic features. It is conspicuous with its distinctly elongated claws and long, hair-like body chaetae. The status of the new species was confirmed by DNA barcoding based on the mitochondrial COI marker. Populations of D. kratochvili (Nosek, 1963), the most widespread species, were studied in detail. Both ABGD and PTP analyses brought results congruent with geography, i.e. the molecular and geographic distance of the populations were positively correlated. However, some molecular separation based on pairwise distance and the number of substitutions was indicated within two of the studied populations. Despite the indistinct morphological differences, the tested populations were well isolated both geographically and genetically, which indicates that each studied population may represent a cryptic species. The troglomorphy of cave Collembola at the northernmost border of the distribution of cave-adapted species in the Europe is discussed. It is clear that the level of troglomorphy is closely associated with conditions of the microhabitat occupied by the individual subterranean species. The results of our study enhance the importance of the Western Carpathians regarding the diversity pattern of obligate cave species in Europe.

New species of the genus Megalothorax Willem, 1900 (Collembola: Neelipleona) from a superficial subterranean habitat at Dobsinská Ice Cave, Slovakia.

New species of Megalothorax Willem, 1900 from Dobsinská Ice Cave, Slovakia, M. dobsinensis sp. n., is described and illustrated. New species inhabits a cold habitat along an inversed temperature gradient at the cave entrance. M. dobsinensis sp. n. differs from other species of the genus by the lack of chaeta X on Ant. IV and by T-shaped inner chaetae of thoracic and abdominal sensory fields. Only two other species, M. tuberculatus Deharveng Beruete, 1993 and M. sanctistephani Christian, 1998 lack chaeta X on Ant. IV. M. dobsinensis sp. n. differs from both species by chaetotaxy of antennae and abdomen. Summary tables of antennae and legs chaetotaxy and dichotomous identification key for species with smooth mucro are provided.

Morphological and cytogenetic characteristics of Neobisium (Blothrus) slovacum Gulicka, 1977 (Pseudoscorpiones, Neobisiidae), the northernmost troglobitic species of the subgenus Blothrus in Europe.

A redescription is provided of the adult, tritonymph and deutonymph life stages of the troglobitic Neobisium (Blothrus) slovacum Gulicka, 1977, which is known from Slovakia and Hungary. Material examined included 35 previously deposited museum specimens and 15 newly collected specimens. In addition, the karyotype and distribution of 18S rDNA clusters are described, using fluorescence in situ hybridization (FISH). The male karyotype of N.slovacum comprises 69 chromosomes, with a predominance of biarmed chromosomes, and an X0 sex chromosome system. Two pairs of signals for 18S rDNA on biarmed chromosomes (submetacentric and metacentric) of different sizes were identified. The present study provides the first information about the distribution of these clusters in the arachnid order Pseudoscorpiones. The geographic distribution of the species is summarized and mapped. Neobisiumslovacum is endemic to the Slovak and Aggtelek Karst area in southern Slovakia and north-western Hungary, where it has been recorded from 16 caves. One of these, Hacavská cave (in Slovakia), is the northernmost locality known for any species of the subgenus Blothrus.

Continental data on cave-dwelling spider communities across Europe (Arachnida: Araneae).

BACKGROUND: Spiders (Arachnida: Araneae) are widespread in subterranean ecosystems worldwide and represent an important component of subterranean trophic webs. Yet, global-scale diversity patterns of subterranean spiders are still mostly unknown. In the frame of the CAWEB project, a European joint network of cave arachnologists, we collected data on cave-dwelling spider communities across Europe in order to explore their continental diversity patterns. Two main datasets were compiled: one listing all subterranean spider species recorded in numerous subterranean localities across Europe and another with high resolution data about the subterranean habitat in which they were collected. From these two datasets, we further generated a third dataset with individual geo-referenced occurrence records for all these species. NEW INFORMATION: Data from 475 geo-referenced subterranean localities (caves, mines and other artificial subterranean sites, interstitial habitats) are herein made available. For each subterranean locality, information about the composition of the spider community is provided, along with local geomorphological and habitat features. Altogether, these communities account for > 300 unique taxonomic entities and 2,091 unique geo-referenced occurrence records, that are made available via the Global Biodiversity Information Facility (GBIF) (Mammola and Cardoso 2019). This dataset is unique in that it covers both a large geographic extent (from 35° south to 67° north) and contains high-resolution local data on geomorphological and habitat features. Given that this kind of high-resolution data are rarely associated with broad-scale datasets used in macroecology, this dataset has high potential for helping researchers in tackling a range of biogeographical and macroecological questions, not necessarily uniquely related to arachnology or subterranean biology.

Erratum: ANDREA PARIMUCHOVÁ & LUBOMÍR KOVÁC (2016) Redescription of two troglobiotic species of Deuteraphorura Absolon, 1901 (Collembola, Onychiuridae) from the Western Carpathians. Zootaxa, 4168: 327-340.

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Riparian Collembola (Hexapoda) communities of northern Moldova, Eastern Europe.

Collembola were studied in a well-preserved riverine section of the Prut River in the Republic of Moldova. The study was focused on species diversity and habitat preferences of the particular species at two localities. Riparian habitats of the Prut River near Braniste included open river bank, forest belt and meadow, and the shore of Lake Costesti-Stânca included meadow, pasture and shrub vegetation. In total 77 collembolan species were recorded, of which Neanura moldavica and Arrhopalites prutensis were endemic to Moldova. Comparative analyses showed a specific community composition at Braniste, with Anurida ellipsoides and Mesaphorura macrochaeta being abundant on the river bank and Hemisotoma thermophila in the meadow. In contrast, the forest plantation at the same locality was similar to the shrub-land in Costesti, with the common species Mesaphorura critica, M. yosii, Deutonura albella and Isotomiella minor. Hygrophilous species preferred the habitats of the river section in Braniste, with quiet backwaters, to the artificial shoreline of the large lake. Species diversity was relatively high in the natural meadow and forest in Braniste and also in shrub-land on the lake shore. The present study documented relatively high collembolan species diversity at the shoreline and running water sections in the upper catchment area of the Prut River in Moldova that involve naturally valuable inundated habitats of Eastern Europe.

A new troglobiotic Protaphorura (Collembola, Hexapoda) from the Siberia, Russia.

A new species of Protaphorura Absolon, 1901 (Collembola, Onychiuridae), P. cykini sp.nov., is described from a cold karst cave in the Irkutsk region, Siberia, Russia. It is an obligate cave species with the largest body size (4.3-5.6 mm) of all congeners. The species is further characteristic by the pseudocellar formula as 3(2)2/022/33343, high number of vesicles in postantennal organ (65-71) and subapical organite protected with two papillae. A partial sequence of cytochrome oxidase I (COI DNA barcoding marker) gene is used to verify the taxonomic status of the new species and the barcode sequence is compared with other congeners available in GenBank database. Distribution and diversity of cave Collembola of Siberia is discussed.

Redescription of two troglobiotic species of Deuteraphorura Absolon, 1901 (Collembola, Onychiuridae) from the Western Carpathians.

Two species of the genus Deuteraphorura Absolon, 1901 from the Western Carpathian caves (Central Europe) are redescribed, namely D. kratochvili (Nosek, 1963) and D. schoenviszkyi (Loksa, 1967). Both species are characterized by the absence of pseudocelli on thoracic tergum I, presence of male ventral organ on abdominal terga II-III and 3 pseudocelli on hind margin of head. D. kratochvili is redescribed based on specimens from the type locality (Demänovská Cave System) and its intraspecific variability in morphological traits is discussed. Redescription of D. schoenviszkyi (Loksa, 1967) is based on specimens from the Slovak and Aggtelek Karst, the karst area where the type locality is situated. Both species are restricted to subterranean environment, thus classified as obligate cave forms (troglobionts). An identification key to Deuteraphorura species, characterized by absence of pseudocelli on thoracic segment I, is provided.

A new cave species of the genus Protaphorura Absolon, 1901 (Collembola, Onychiuridae) from the Western Carpathians (Slovakia) with critical comments to the Palaearctic representatives of the genus.

The new species Protaphorura borinensis sp. nov. from a cave of the Western Carpathians, Central Europe, is described. It belongs to congeners with ~40 vesicles in PAO and three pseudocelli at the base of antennae and the hind margin of head. P. borinensis sp. nov. has coarse granulation of cuticle on head, and specific distribution of "s" chaetae on abdominal terga and chaetotaxy of ventral tube. Critical comments to the Palaearctic representatives of the genus Protaphorura and an identification key to 85 species are provided.