Island hoppers : Integrative taxonomic revision of Hogna wolf spiders (Araneae, Lycosidae) endemic to the Madeira islands with description of a new species

Because of their ability for aerial dispersal using silk and preference for open habitats, many wolf spiders are formidable colonisers. Pioneering arachnologists were already aware of the large and colourful wolf spiders in the Madeira archipelago, currently included in the genus Hogna Simon, 1885. The origins were investigated and species boundaries of Madeiran Hogna examined by integrating target-gene and mor-phological information. A multi-locus phylogenetic analysis of a thorough sampling across wolf-spider diversity suggested a single origin of Madeiran endemics, albeit with low support. Divergence time estima-tion traced back their origin to the late Miocene, a time of major global cooling that drove the expansion of grasslands and the associated fauna. Morphological examination of types and newly collected material revealed a new species, hereby described as H. isambertoi Crespo, sp. nov. Additionally, H. blackwalli is revalidated and three new synonymies are proposed, namely H. biscoitoi Wunderlich, 1992, junior syno-nym of H. insularum Kulczynski, 1899, H. schmitzi Wunderlich, 1992, junior synonym of H. maderiana (Walckenaer, 1837), and Arctosa maderana Roewer, 1960 junior synonym of H. ferox (Lucas, 1838). Spe-cies delimitation analyses of mitochondrial and nuclear markers provided additional support for morpho-logical delineations. The species pair H. insularum and H. maderiana, however, constituted an exception: the lack of exclusive haplotypes in the examined markers, along with the discovery of intermediate forms, pointed to hybridisation between these two species as reported in other congeneric species on islands. Finally, the conservation status of the species is discussed and candidates for immediate conservation efforts are identified.Peer reviewe

Changing feeding habits and ontogenetic dimorphism in juveniles and adults Aplysia punctata (Cuvier, 1803) (Mollusca, Gastropoda, Heterobranchia) in the Mediterranean Sea

Specimens of Aplysia punctata inhabiting the Catalonian coast (NE Spain, Western Mediterranean Sea) display two different color patterns, which have been thought to represent two distinct species. However, molecular analyses conducted by other authors and confirmed herein show that there are no genetic differences between individuals of the two color morphs. At the same time these color morphs display distinct life history traits, including different size, mating behavior, and egg mass and larvae coloration. In this paper, it is hypothesized that distinct diets are responsible of these differences. The results of this study confirm that small red specimens of A. punctata feed on red algae and primarily Sphaerococcus coronopifolius and Plocamium cartilagineum; pigments from these algae give small specimens of A. punctata a very similar morphological appearance to adults of the Aplysia parvula species complex. In contrast, adult specimens of A. punctata feed preferentially on green algae of the species Ulva lactuca. This change in feeding behavior is probably related to defensive strategies involving camouflage. In addition, the egg masses take on a pink to reddish color that is retained in the larval stage of A. punctata juveniles

What DNA barcodes reveal : microhabitat preference, hunting strategy and dispersal ability drive genetic variation across Iberian spider species

1. The current rate of species loss calls for immediate actions to preserve biodiversity and ecosystem functioning. Cataloguing species richness and composition, and revealing how diversity is geographically distributed are the first steps towards designing efficient conservation strategies. 2. Here, we aim to determine diversity patterns and potential drivers of taxonomic and genetic diversity and population structure of Iberian spiders. We used a community level perspective, analysing more than 3000 DNA barcode sequences representing similar to 370 spider species dwelling in white-oak forest habitats across the Spanish National Park network. 3. By combining and comparing morphological and DNA barcode-based species delimitation methods, we assessed their performance and identified putative factors behind cases of incongruence. Our findings uncovered potential overlooked diversity as suggested by the geographic patterns of genetic variation and put a red flag on those taxa that may be undergoing overlooked evolutionary or ecological processes. 4. Spider functional traits associated with foraging strategy, microhabitat preference, ballooning ability and circadian activity explained the observed patterns of population structure across species but did not explain variation in genetic diversity. Overall, our study represents a major step forward in the understanding of large-scale diversity patterns in Iberian spiders at the community level and provides relevant information to guide future conservation strategies of the so-far largely overlooked invertebrate diversity.Peer reviewe

For all audiences : Incorporating immature stages into standardised spider inventories has a major impact on the assessment of biodiversity patterns

Although arthropods are the largest component of animal diversity, they are traditionally underrepresented in biological inventories and monitoring programmes. However, no biodiversity assessment can be considered informative without including them. Arthropod immature stages are often discarded during sorting, despite frequently representing more than half of the collected individuals. To date, little effort has been devoted to characterising the impact of discarding nonadult specimens on our diversity estimates. Here, we used a metabarcoding approach to analyse spiders from oak forests in the Iberian Peninsula, to assess (1) the contribution of juvenile stages to local diversity estimates, and (2) their effect on the diversity patterns (compositional differences) across assemblages. We further investigated the ability of metabarcoding to inform on abundance. We obtained 363 and 331 species as adults and juveniles, respectively. Including the species represented only by juveniles increased the species richness of the whole sampling in 35% with respect to those identified from adults. Differences in composition between assemblages were greatly reduced when immature stages were considered, especially across latitudes, possibly due to phenological differences. Moreover, our results revealed that metabarcoding data are to a certain extent quantitative, but some sort of taxonomic conversion factor may be necessary to provide accurate informative estimates. Although our findings do not question the relevance of the information provided by adult-based inventories, they also reveal that juveniles provide a novel and relevant layer of knowledge that, especially in areas with marked seasonality, may influence our interpretations, providing more accurate information from standardised biological inventories.Peer reviewe

What DNA barcodes reveal: microhabitat preference, hunting strategy and dispersal ability drive genetic variation across Iberian spider species

1. The current rate of species loss calls for immediate actions to preserve biodiversity and ecosystem functioning. Cataloguing species richness and composition, and revealing how diversity is geographically distributed are the first steps towards designing efficient conservation strategies. 2. Here, we aim to determine diversity patterns and potential drivers of taxonomic and genetic diversity and population structure of Iberian spiders. We used a community level perspective, analysing more than 3000 DNA barcode sequences representing 370 spider species dwelling in white-oak forest habitats across the Spanish National Park network. 3. By combining and comparing morphological and DNA barcode-based species delimitation methods, we assessed their performance and identified putative factors behind cases of incongruence. Our findings uncovered potential overlooked diversity as suggested by the geographic patterns of genetic variation and put a red flag on those taxa that may be undergoing overlooked evolutionary or ecological processes. 4. Spider functional traits associated with foraging strategy, microhabitat preference, ballooning ability and circadian activity explained the observed patterns of population structure across species but did not explain variation in genetic diversity. Overall, our study represents a major step forward in the understanding of large-scale diversity patterns in Iberian spiders at the community level and provides relevant information to guide future conservation strategies of the so-far largely overlooked invertebrate diversit

For all audiences: Incorporating immature stages into standardised spider inventories has a major impact on the assessment of biodiversity patterns

Although arthropods are the largest component of animal diversity, they are traditionally underrepresented in biological inventories and monitoring programmes. However, no biodiversity assessment can be considered informative without including them. Arthropod immature stages are often discarded during sorting, despite frequently representing more than half of the collected individuals. To date, little effort has been devoted to characterising the impact of discarding nonadult specimens on our diversity estimates. Here, we used a metabarcoding approach to analyse spiders from oak forests in the Iberian Peninsula, to assess (1) the contribution of juvenile stages to local diversity estimates, and (2) their effect on the diversity patterns (compositional differences) across assemblages. We further investigated the ability of metabarcoding to inform on abundance. We obtained 363 and 331 species as adults and juveniles, respectively. Including the species represented only by juveniles increased the species richness of the whole sampling in 35% with respect to those identified from adults. Differences in composition between assemblages were greatly reduced when immature stages were considered, especially across latitudes, possibly due to phenological differences. Moreover, our results revealed that metabarcoding data are to a certain extent quantitative, but some sort of taxonomic conversion factor may be necessary to provide accurate informative estimates. Although our findings do not question the relevance of the information provided by adult-based inventories, they also reveal that juveniles provide a novel and relevant layer of knowledge that, especially in areas with marked seasonality, may influence our interpretations, providing more accurate information from standardised biological inventories

Building a Robust, Densely-Sampled Spider Tree of Life for Ecosystem Research

Phylogenetic relatedness is a key diversity measure for the analysis and understanding of how species and communities evolve across time and space. Understanding the nonrandom loss of species with respect to phylogeny is also essential for better-informed conservation decisions. However, several factors are known to influence phylogenetic reconstruction and, ultimately, phylogenetic diversity metrics. In this study, we empirically tested how some of these factors (topological constraint, taxon sampling, genetic markers and calibration) affect phylogenetic resolution and uncertainty. We built a densely sampled, species-level phylogenetic tree for spiders, combining Sanger sequencing of species from local communities of two biogeographical regions (Iberian Peninsula and Macaronesia) with a taxon-rich backbone matrix of Genbank sequences and a topological constraint derived from recent phylogenomic studies. The resulting tree constitutes the most complete spider phylogeny to date, both in terms of terminals and background information, and may serve as a standard reference for the analysis of phylogenetic diversity patterns at the community level. We then used this tree to investigate how partial data affect phylogenetic reconstruction, phylogenetic diversity estimates and their rankings, and, ultimately, the ecological processes inferred for each community. We found that the incorporation of a single slowly evolving marker (28S) to the DNA barcode sequences from local communities, had the highest impact on tree topology, closely followed by the use of a backbone matrix. The increase in missing data resulting from combining partial sequences from local communities only had a moderate impact on the resulting trees, similar to the difference observed when using topological constraints. Our study further revealed substantial differences in both the phylogenetic structure and diversity rankings of the analyzed communities estimated from the different phylogenetic treatments, especially when using non-ultrametric trees (phylograms) instead of time-stamped trees (chronograms). Finally, we provide some recommendations on reconstructing phylogenetic trees to infer phylogenetic diversity within ecological studies

Mitochondrial discordance in closely related Theridion spiders (Araneae, Theridiidae), with description of a new species of the T. melanurum group

The incorporation of molecular data into current taxonomic practise has unravelled instances of incongruence among different data sets. Here we report a case of mitochondrial discordance in cobweb spiders of the genus Theridion Walckenaer, 1805 from the Iberian Peninsula. Morphological examination of samples from a country-wide bioinventory initiative revealed the existence of a putative new species and two nominal species belonging to the Theridion melanurum species group. The morphological delineation was supported by the molecular analysis of a nuclear marker but was at odds with the groups circumscribed by a mitochondrial marker. The causes of this discordance remained uncertain, once sample and sequencing errors and the existence of pseudogenes were discarded. The full sorting observed in the alleles of the more slowly evolving nuclear marker ruled out incomplete lineage sorting, while the geographic patterns recovered were difficult to reconciliate with ongoing hybridization. We propose that the apparent incongruence observed is most likely the result of old introgression events in a group with high dispersal abilities. We further speculate that endosymbiont-driven cytoplasmatic incompatibility could be involved in the fixation of mitochondrial haplotypes across species barriers. Additionally, we describe the new species T. promiscuum sp. nov., based on the presence of diagnostic morphological traits, backed up by the nuclear data delimitation. Our study contributes yet another example of the perils of relying on single methods or data sources to summarise the variation generated by multiple processes acting through thousands of years of evolution and supports the key role of biological inventories in improving our knowledge of invertebrate biodiversity

Island hoppers: Integrative taxonomic revision of Hogna wolf spiders (Araneae, Lycosidae) endemic to the Madeira islands with description of a new species

Because of their ability for aerial dispersal using silk and preference for open habitats, many wolf spiders are formidable colonisers. Pioneering arachnologists were already aware of the large and colourful wolf spiders in the Madeira archipelago, currently included in the genus Hogna Simon, 1885. The origins were investigated and species boundaries of Madeiran Hogna examined by integrating target-gene and mor- phological information. A multi-locus phylogenetic analysis of a thorough sampling across wolf-spider diversity suggested a single origin of Madeiran endemics, albeit with low support. Divergence time estima- tion traced back their origin to the late Miocene, a time of major global cooling that drove the expansion of grasslands and the associated fauna. Morphological examination of types and newly collected material revealed a new species, hereby described as H. isambertoi Crespo, sp. nov. Additionally, H. blackwalli is revalidated and three new synonymies are proposed, namely H. biscoitoi Wunderlich, 1992, junior syno- nym of H. insularum Kulczynski, 1899, H. schmitzi Wunderlich, 1992, junior synonym of H. maderiana (Walckenaer, 1837), and Arctosa maderana Roewer, 1960 junior synonym of H. ferox (Lucas, 1838). Spe- cies delimitation analyses of mitochondrial and nuclear markers provided additional support for morpho- logical delineations. The species pair H. insularum and H. maderiana, however, constituted an exception: the lack of exclusive haplotypes in the examined markers, along with the discovery of intermediate forms,pointed to hybridisation between these two species as reported in other congeneric species on islands. Finally, the conservation status of the species is discussed and candidates for immediate conservation ef- forts are identifie

Systematics and phylogeography of western Mediterranean tarantulas (Araneae: Theraphosidae)

Theraphosidae is the most diversified family of mygalomorph spiders, commonly known as tarantulas. Two genera inhabit the Mediterranean region: Chaetopelma in the east and Ischnocolus mostly in the western part of the Basin. Their phylogenetic position and the validity of some Ischnocolus species remain unclear. We implemented a multilocus target approach to shed new light on the position of both genera and further integrated molecular data with additional lines of evidence (morphology and ecology) to explore species boundaries in western Mediterranean Ischnocolus. Our results reveal that Ischnocolus and Chaetopelma are not closely related. Chaetopelma formed a clade with the African subfamily Eumenophorinae and Ischnocolus was recovered in a clade comprising all remaining theraphosids. The western Mediterranean Ischnocolus comprises two deeply divergent clades that separated during the Early Miocene and differ in both morphology and lifestyle. We found molecular, morphological and ecological evidence to restore the name Ischnocolus mogadorensis and revalidate this species. We also uncovered distinct allopatric lineages in Ischnocolus elongatus. However, the lack of males, the uniform morphology of females and low within-clade support hampered the assessment of their status and boundaries. Finally, our data support that I. elongatus should be considered a senior synonym of Ischnocolus hancocki and Harpactirella insidiosa.Peer reviewe