Search

Copyright of Arachnology Letters / Arachnologische Mitteilungen is the property of Arachnologische Gesellschaft e.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Most of our understanding of island diversity comes from the study of aboveground systems, while the patterns and processes of diversification and community assembly for belowground biotas remain poorly understood. Here, we take advantage of a relatively young and dynamic oceanic island to advance our understanding of ecoevolutionary processes driving community assembly within soil mesofauna. Using whole organism community DNA (wocDNA) metabarcoding and the recently developed metaMATE pipeline, we have generated spatially explicit and reliable haplotype‐level DNA sequence data for soil mesofaunal assemblages sampled across the four main habitats within the island of Tenerife. Community ecological and metaphylogeographic analyses have been performed at multiple levels of genetic similarity, from haplotypes to species and supraspecific groupings. Broadly consistent patterns of local‐scale species richness across different insular habitats have been found, whereas local insular richness is lower than in continental settings. Our results reveal an important role for niche conservatism as a driver of insular community assembly of soil mesofauna, with only limited evidence for habitat shifts promoting diversification. Furthermore, support is found for a fundamental role of habitat in the assembly of soil mesofauna, where habitat specialism is mainly due to colonization and the establishment of preadapted species. Hierarchical patterns of distance decay at the community level and metaphylogeographical analyses support a pattern of geographic structuring over limited spatial scales, from the level of haplotypes through to species and lineages, as expected for taxa with strong dispersal limitations. Our results demonstrate the potential for wocDNA metabarcoding to advance our understanding of biodiversity. [ABSTRACT FROM AUTHOR]

Copyright of Arachnology Letters / Arachnologische Mitteilungen is the property of Arachnologische Gesellschaft e.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aim: Habitat diversity has been linked to the diversity and structure of island communities, however, little is known about patterns and processes within habitats. Here we aim to determine the contributions of habitat type and inferred dispersal frequency to the differences in taxonomic structure between assemblages in the same island habitat. Location: The Macaronesian archipelagos (Azores, Madeira, the Canary Islands and Cabo Verde). Taxon: Spiders (Araneae). Methods: We established forest and dry habitat sites (each with five plots) on two islands per archipelago. We collected spiders using standardised sampling protocols. We tested the differences in beta diversity separately for each habitat and for each inferred category of ballooning (an aerial dispersal strategy) frequency across geographic scales through nested non-parametric permutational multivariate analyses of variance. We then tested whether ballooning and habitat influenced heterogeneity in species composition (dispersion in beta diversity) in the two habitat types. We analysed the effects of habitat and ballooning on species abundance distribution (SAD) and rarity by fitting Gambin models and evaluating the contribution of ballooning categories to SAD. Results: Communities of the same archipelago and habitat were taxonomically more similar, and beta diversity increased with geographic scale, being greater in dry habitats. There was greater species replacement among assemblages in dry habitats than in forests, with greater differences for rare ballooners. There were no differences in SAD between habitats although dry habitat sites seemed to harbour more species with low abundances (rare species) than forests. Main conclusions: Habitat type does not only condition the differences between spider assemblages of the same habitat but also the scale at which they occur. These differences may be determined by the heterogeneity in the physical structure of each habitat as well as how much this structure facilitates aerial dispersal (ballooning), and should be considered in theories/hypotheses on island community assembly as well as in conservation strategies. [ABSTRACT FROM AUTHOR]

The genus Baezia Alonso-Zarazaga & García, 1999 is endemic to the Canary Islands, where four species were known to date. Based on morphological evidence, three new species of Baezia are described in this study: Baezia aranfaybo García & López, sp. nov. from El Hierro island, and Baezia madai García & Oromí sp. nov. and Baezia tizziri García & Andújar, sp. nov. from La Palma island. Notes on their biology, habitat, and distribution are presented. The number of taxa in this endemic Canarian genus increases to seven eyeless species. One species has been reported from the soil (endogean environment), with the other six associated with caves and the mesovoid shallow substratum (hypogean or subterranean environment). Frequent association with the presence of roots suggests that species of Baezia may inhabit the continuum represented by the endogean and hypogean environments. Identification key to the seven species are provided. [ABSTRACT FROM AUTHOR]

Abstract Background The amphipod crustacean Palmorchestia hypogaea occurs only in La Palma (Canary Islands) and is one of the few terrestrial amphipods in the world that have adapted to a strictly troglobitic life in volcanic cave habitats. A surface-dwelling closely related species (Palmorchestia epigaea) lives in the humid laurel forest on the same island. Previous studies have suggested that an ancestral littoral Orchestia species colonized the humid forests of La Palma and that subsequent drought episodes in the Canaries reduced the distribution of P. epigaea favouring the colonization of lava tubes through an adaptive shift. This was followed by dispersal via the hypogean crevicular system. Results P. hypogaea and P. epigaea did not form reciprocally monophyletic mitochondrial DNA clades. They showed geographically highly structured and genetically divergent populations with current gene flow limited to geographically close surface locations. Coalescence times using Bayesian estimations assuming a non-correlated relaxed clock with a normal prior distribution of the age of La Palma, together with the lack of association of habitat type with ancestral and recent haplotypes, suggest that their adaptation to cave life is relatively ancient. Conclusion The data gathered here provide evidence for multiple invasions of the volcanic cave systems that have acted as refuges. A re-evaluation of the taxonomic status of the extant species of Palmorchestia is needed, as the division of the two species by habitat and ecology is unnatural. The information obtained here, and that from previous studies on hypogean fauna, shows the importance of factors such as the uncoupling of morphological and genetic evolution, the role of climatic change and regressive evolution as key processes in leading to subterranean biodiversity.

A new blind weevil belonging to the genus Oromia Alonso-Zarazaga, 1987 is described, being found in the underground of the laurel forest of La Gomera (Canary Islands). Individuals were mainly collected in a colluvial mesocavernous shallow substratum, besides one specimen collected in the deep humic layer of soil. This new species has clear diagnostic differences from the other Oromia species. The number of taxa in this endemic Canarian genus increases to four species, easily identified using the key provided in this article. New data on other Canarian subterranean weevils are also provided. [ABSTRACT FROM AUTHOR]

Two new dipluran species of the family Campodeidae have been unearthed in the Canary Islands. Remycampa herbanica sp. nov. was found in a highly threatened lava tube on Fuerteventura island. It is related to the soil-dwelling northwest African Remycampa launeyi that also inhabits four of the Canary Islands. The two known Remycampa species are characterized by a torsion of the labial palps. They differ chiefly in the distribution of macrosetae and in the features of cave adaptation of R. herbanica, i.e. elongation of body and appendages, and a higher number of olfactory chemoreceptors with a coniform shape unique within campodeids. Spaniocampa relicta sp. nov. was collected in the mesovoid shallow substratum (MSS) and has been assigned to a formerly monotypic genus that includes the soil-dwelling Spaniocampa prima from the Republic of Guinea. The two species differ in the number of abdominal macrosetae. Females of S. relicta sp. nov. have small setae arranged in groups along the posterior border of the first urosternite. These structures of unknown function have never been described in other campodeid species. Sequencing the COI barcode region of R. herbanica has been produced but it proved insufficient to identify closest relatives. The two new hexapods from subterranean habitats raise the Canarian campodeid fauna to six species. Five of them are living in soil and/or MSS, whereas the cave-adapted R. herbanica is known only from a single, particularly endangered lava tube distant from other caves. [ABSTRACT FROM AUTHOR]

Geographic isolation substantially contributes to species endemism on oceanic islands when speciation involves the colonisation of a new island. However, less is understood about the drivers of speciation within islands. What is lacking is a general understanding of the geographic scale of gene flow limitation within islands, and thus the spatial scale and drivers of geographical speciation within insular contexts. Using a community of beetle species, we show that when dispersal ability and climate tolerance are restricted, microclimatic variation over distances of only a few kilometres can maintain strong geographic isolation extending back several millions of years. Further to this, we demonstrate congruent diversification with gene flow across species, mediated by Quaternary climate oscillations that have facilitated a dynamic of isolation and secondary contact. The unprecedented scale of parallel species responses to a common environmental driver for evolutionary change has profound consequences for understanding past and future species responses to climate variation. [ABSTRACT FROM AUTHOR]

Obtaining fundamental biodiversity metrics such as alpha, beta and gamma diversity for arthropods is often complicated by a lack of prior taxonomic information and/or taxonomic expertise, which can result in unreliable morphologically based estimates. We provide a set of standardized ecological and molecular sampling protocols that can be employed by researchers whose taxonomic skills may be limited, and where there may be a lack of robust a priori information regarding the regional pool of species. These protocols combine mass sampling of arthropods, classification of samples into parataxonomic units ( PUs) and selective sampling of individuals for mt DNA sequencing to infer biological species. We sampled ten lowland rainforest plots located on the volcanic oceanic island of Réunion (Mascarene archipelago) for spiders, a group with limited taxonomic and distributional data for this region. We classified adults and juveniles into PUs and then demonstrated the reconciliation of these units with presumed biological species using mt DNA sequence data, ecological data and distributional data. Because our species assignment protocol is not reliant upon prior taxonomic information, or taxonomic expertise, it minimizes the problem of the Linnean shortfall to yield diversity estimates that can be directly compared across independent studies. Field sampling can be extended to other arthropod groups and habitats by adapting our field sampling protocol accordingly. [ABSTRACT FROM AUTHOR]

Using a series of standardized sampling plots within forest ecosystems in remote oceanic islands, we reveal fundamental differences between the structuring of aboveground and belowground arthropod biodiversity that are likely due to large-scale species introductions by humans. Species of beetle and spider were sampled almost exclusively from single islands, while soil-dwelling Collembola exhibited more than tenfold higher species sharing among islands. Comparison of Collembola mitochondrial metagenomic data to a database of more than 80 000 Collembola barcode sequences revealed almost 30% of sampled island species are genetically identical, or near identical, to individuals sampled from often very distant geographic regions of the world. Patterns of mt DNA relatedness among Collembola implicate human-mediated species introductions, with minimum estimates for the proportion of introduced species on the sampled islands ranging from 45% to 88%. Our results call for more attention to soil mesofauna to understand the global extent and ecological consequences of species introductions. [ABSTRACT FROM AUTHOR]

The ground-dweller spider genus Dysdera shows very high species richness on the oceanic archipelago of the Canary Islands, providing one of the most outstanding examples of island radiation among spiders, only paralleled by Tetragnatha spiders on the Hawaiian archipelago. A georeferenced database of the 48 Dysdera species occurring in the Canary Islands was assembled to facilitate ongoing and future research on this remarkable lineage. All species are endemic to the archipelago except for the cosmopolitan Dysdera crocata. The dataset consists of 794 distributional records documented from 1971 to 2015, each locality being represented only once per species. Distribution maps are provided for each species, along with basic diversity and distribution information. The database and geographical maps included in this article stand for the most updated, accurate and complete information on the distribution of the spider genus Dysdera in the Canary Islands. [ABSTRACT FROM AUTHOR]

1. The large flightless grasshopper Acrostira bellamyi Uvarov, endemic to the island of La Gomera ( Canary Islands), inhabits two different environments: the xeric euphorb shrubland, as is typical for congeneric Canarian species, and the humid laurel forest, a novel habitat for the genus. 2. We investigate genetic, morphological, and ecological variation among individuals of A. bellamyi from the two habitats. DNA sequence data were used to evaluate whether grasshoppers from the two environments represent distinct lineages. Morphological and trophic analyses were performed to assess phenotypic differentiation between the two different habitats. 3. Population genetic analyses support the hypothesis that the euphorb shrubland is the ancestral habitat for this species. Female laurel forest specimens are larger than those inhabiting the euphorb shrubland, and some external body parts exhibit significant morphometric differences between the two populations. Diet of shrubland individuals is completely different from that of laurel forest individuals. Although in each habitat they consume the most abundant plants, individuals are able to select food plants, which appear to be explained by their nutrient content. 4. Our results suggest that A. bellamyi has colonised laurel forest from shrubland, and that this habitat shift has resulted in genetic, morphological, and ecological changes, perhaps as an adaptation to this new habitat. [ABSTRACT FROM AUTHOR]

Recent studies on the endemic Canarian genus Purpuraria have shown that the taxonomy of its only recognized species ( P. erna) is probably erroneous. In this study, an integrative revision of the genus is performed, based on a large number of specimens and geographical sampling. As a result, (1) the diagnostic characters at the genus level are re-described, (2) Purpuraria magna n. sp. based on morphological, morphometric and genetic data is described and (3) the taxonomic status of a formerly described subspecies is clarified. Intraspecific and interspecific morphometric differences have been found, indicating that the genus is undergoing a process of morphological diversification. Nevertheless, the possibility of interspecific mating between individuals of the two species is suggested, because no significant differences have been found between their respective calling songs. Genetic analyses using mitochondrial and nuclear DNA sequences suggest that P. erna and P. magna are recent species with evidences of secondary contact episodes in the past. [ABSTRACT FROM AUTHOR]

Comparative phylogeography seeks for commonalities in the spatial demographic history of sympatric organisms to characterize the mechanisms that shaped such patterns. The unveiling of incongruent phylogeographic patterns in co-occurring species, on the other hand, may hint to overlooked differences in their life histories or microhabitat preferences. The woodlouse-hunter spiders of the genus Dysdera have undergone a major diversification on the Canary Islands. The species pair Dysdera alegranzaensis and Dysdera nesiotes are endemic to the island of Lanzarote and nearby islets, where they co-occur at most of their known localities. The two species stand in sharp contrast to other sympatric endemic Dysdera in showing no evidence of somatic (non-genitalic) differentiation. Phylogenetic and population genetic analyses of mitochondrial cox1 sequences from an exhaustive sample of D. alegranzaensis and D. nesiotes specimens, and additional mitochondrial ( 16S , L1, nad1) and nuclear genes ( 28S, H3) were analysed to reveal their phylogeographic patterns and clarify their phylogenetic relationships. Relaxed molecular clock models using five calibration points were further used to estimate divergence times between species and populations. Striking differences in phylogeography and population structure between the two species were observed. Dysdera nesiotes displayed a metapopulation-like structure, while D. alegranzaensis was characterized by a weaker geographical structure but greater genetic divergences among its main haplotype lineages, suggesting more complex population dynamics. Our study confirms that co-distributed sibling species may exhibit contrasting phylogeographic patterns in the absence of somatic differentiation. Further ecological studies, however, will be necessary to clarify whether the contrasting phylogeographies may hint at an overlooked niche partitioning between the two species. In addition, further comparisons with available phylogeographic data of other eastern Canarian Dysdera endemics confirm the key role of lava flows in structuring local populations in oceanic islands and identify localities that acted as refugia during volcanic eruptions. [ABSTRACT FROM AUTHOR]

A bibliographic analysis of the hypogean biological studies in Portugal is made, compiling 138 publications related to the subterranean invertebrate fauna, since its begining in 1870 until November 2012. A catalogue of hypogean endemic taxa is provided, listing 27 troglobionts and 63 stygobionts, described to be obligate hypogean and endemic from mainland Portugal (Macaronesian archipelagos excluded). The first impetus on troglobiont studies was provided by the prospections of Barros Machado during 1940's and by an expedition of Lindberg in the spring of 1961; and the major information about stygobiont species was provided by the former Instituto de Zoologia "Dr. Augusto Nobre" from Porto University. [ABSTRACT FROM AUTHOR]

Within the soil matrix and underlying rock, cracks and fissures and other air-filled spaces between rocks, sometimes called the milieu souterrain superficiel (MSS), are present in a variety of geological contexts. We examined year-long hourly temperature profiles at sites in lava in the Canary Islands and limestone in Slovenia. All sites had species that show morphological adaptations usually associated with cave-dwelling organisms, including elongated appendages and reduced eyes and pigment. MSS sites were studied at depths between 10 and 70 cm and showed strong seasonality, and most had a discernible diurnal cycle as well. The most striking difference from surface habitats was that the temperature extremes were much less pronounced in MSS sites. Temperature variability was not correlated with troglobiotic species richness. The presence of species with similar morphologies to those found in caves indicates that selective pressures are similar in cave and shallow subterranean habitats. [ABSTRACT FROM AUTHOR]

The development of molecular techniques as a taxonomic tool and their integration with information provided by other disciplines, has enhanced species discovery, facilitated species delimitation and produced invaluable data for inferring species phylogenies. Here, we provide an example of how DNA sequence data, together with morphometric, distributional and ecological information, assist in identifying and diagnosing previously overlooked lineages. The nocturnal, ground-dwelling spider genus Dysdera has colonized all the Macaronesian archipelagos, and has undergone a major diversification in the Canary Islands. A recent molecular phylogenetic analysis of Dysdera species from the eastern Canary Islands revealed deep genetic divergences among some populations, suggesting the existence of cryptic taxa. Here, we combine data from mitochondrial and nuclear loci with morphological and ecological evidence to delimit and formally describe three previously overlooked species: D. aneris sp. nov., endemic to the Salvage Islands; D. mahan sp. nov., distributed along coastal habitats of Lanzarote, north of Fuerteventura and adjacent islets; and D. simbeque sp. nov., restricted to two valleys in northern Lanzarote. Molecular markers provide key information that allows apparent morphological polymorphisms to be used as diagnostic features of evolutionarily independent lineages. Dysdera mahan sp. nov. is unique among the Canarian Dysdera in that it is found in the intertidal zone on pebbled beaches. Low levels of genetic variability and genital differentiation associated with relatively high somatic divergence suggest that speciation in D. mahan sp. nov. was driven by a selection of phenotypic traits that are adaptive to this rare environment. Separate analyses and statistical tests revealed phylogenetic incongruence between mitochondrial and nuclear genes, probably as a result of incomplete lineage sorting. The temporal framework for the origin and diversification of the new species inferred from the molecular data corroborates former hypotheses on the late Pliocene origin of the present-day biota of the Salvage Islands. [ABSTRACT FROM AUTHOR]

We investigated the phylogenetic patterns, evolutionary processes, and their taxonomic implications, of two closely related shield-backed katydid genera endemic to the Macaronesian archipelagos: the monotypic Psalmatophanes Chopard, 1938 endemic to Madeira and Calliphona Krauss, 1892, which includes three species restricted to the Canary Islands. Two main hypotheses have been proposed to explain the origin and colonization pathways of these two genera: a single origin with subsequent sequential colonization of the islands, or three independent colonization waves from continental Africa. We used DNA sequence information from the mitochondrial genes cox1, tRNAleucine, rrnL and nad1 to infer phylogenetic relationships among Psalmatophanes and Calliphona species. Our results provide support for the independent colonization of Madeira and the Canary Islands, and suggest that Psalmatophanes is actually more closely related to the continental genus Tettigonia than to the Canarian representatives. Deep genetic divergence among Canarian species provides further support for the assignment of the Canarian species into two subgenera. Tree topology along with Bayesian-based estimates of lineage age suggest a pattern of colonization from Tenerife to La Palma, and from Tenerife to Gran Canaria with subsequent dispersal to La Gomera. We report the first collection of a Calliphona specimen in the island of El Hierro, which molecular data suggest is a recent immigrant from La Gomera. We hypothesize that the patterns of distribution and genetic divergence exhibited by Calliphona in the Canary Islands are compatible with a taxon cycle process. Our results have further implications for the higher level phylogeny of the subfamily Tettigoniinae and suggest that some of the tribes as currently delimited may not correspond to natural groups. [ABSTRACT FROM AUTHOR]