Search

The Sox family of transcription factors regulates many processes during metazoan development, including stem cell maintenance and nervous system specification. Characterizing the repertoires and roles of these genes can therefore provide important insights into animal evolution and development. We further characterized the Sox repertoires of several arachnid species with and without an ancestral whole-genome duplication and compared their expression between the spider Parasteatoda tepidariorum and the harvestman Phalangium opilio. We found that most Sox families have been retained as ohnologs after whole-genome duplication and evidence for potential subfunctionalization and/or neofunctionalization events. Our results also suggest that Sox21b-1 likely regulated segmentation ancestrally in arachnids, playing a similar role to the closely related SoxB gene, Dichaete, in insects. We previously showed that Sox21b-1 is required for the simultaneous formation of prosomal segments and sequential addition of opisthosomal segments in P. tepidariorum. We studied the expression and function of Sox21b-1 further in this spider and found that although this gene regulates the generation of both prosomal and opisthosomal segments, it plays different roles in the formation of these tagmata reflecting their contrasting modes of segmentation and deployment of gene regulatory networks with different architectures., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

The majority of extant arachnids are terrestrial, but other chelicerates are generally aquatic, including horseshoe crabs, sea spiders, and the extinct eurypterids. It is necessary to determine whether arachnids are exclusively descended from a single common ancestor (monophyly), because only that relationship is compatible with one land colonisation in chelicerate evolutionary history. Some studies have cast doubt on arachnid monophyly and recast the origins of their terrestrialization. These include some phylogenomic analyses placing horseshoe crabs within Arachnida, and from aquatic Palaeozoic stem-group scorpions. Here, we evaluate the possibility of arachnid monophyly by considering morphology, fossils and molecules holistically. We argue arachnid monophyly obviates the need to posit reacquisition/retention of aquatic characters such as gnathobasic feeding and book gills without trabeculae from terrestrial ancestors in horseshoe crabs, and that the scorpion total-group contains few aquatic taxa. We built a matrix composed of 200 slowly-evolving genes and re-analysed two published molecular datasets. We retrieved arachnid monophyly where other studies did not - highlighting the difficulty of resolving chelicerate relationships from current molecular data. As such, we consider arachnid monophyly the best-supported hypothesis. Finally, we inferred that arachnids terrestrialized during the Cambrian-Ordovician using the slow-evolving molecular matrix, in agreement with recent analyses., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Hemocyanin (Hc), a copper-containing extracellular multimeric protein, is the major protein component of hemolymph in different arachnid groups. Hc possesses 7 or 8 very well-characterized types of monomers with molecular weights ranging from 70 to 85 kDa, organized in hexamers or multiple of hexamers. The present chapter compiles the existing data with relation to the function of this protein in the arachnids. Hc has as main function the reversible transport of O 2 , but it shows many secondary though not less important functions. With reference to this, it has been described that Hc can transport hydrophobic molecules (lipid-derived hormones and lipids) to the different organs, having a key role in the lipid transport system. In arachnids, like in other arthropods and invertebrates, Hc has phenoloxidase function which is related to different metabolic processes such as melanin formation and defense against pathogens. In addition, Hc has additional defensive functions since it can serve as precursor for the production of antimicrobial peptides. In short, the evolution of this protein has led to the development of multiple functions essential for organisms possessing this protein.

Horseshoe crabs (Xiphosura) are traditionally regarded as sister group to the clade of terrestrial chelicerates (Arachnida). This hypothesis has been challenged by recent phylogenomic analyses, but the non-monophyly of Arachnida has consistently been disregarded as artifactual. We re-evaluated the placement of Xiphosura among chelicerates using the most complete phylogenetic data set to date, expanding outgroup sampling, and including data from whole genome sequencing projects. In spite of uncertainty in the placement of some arachnid clades, all analyses show Xiphosura consistently nested within Arachnida as the sister group to Ricinulei (hooded tick spiders). It is apparent that the radiation of arachnids is an old one and occurred over a brief period of time, resulting in several consecutive short internodes, and thus is a potential case for the confounding effects of incomplete lineage sorting (ILS). We simulated coalescent gene trees to explore the effects of increasing levels of ILS on the placement of horseshoe crabs. In addition, common sources of systematic error were evaluated, as well as the effects of fast-evolving partitions and the dynamics of problematic long branch orders. Our results indicated that the placement of horseshoe crabs cannot be explained by missing data, compositional biases, saturation, or ILS. Interrogation of the phylogenetic signal showed that the majority of loci favor the derived placement of Xiphosura over a monophyletic Arachnida. Our analyses support the inference that horseshoe crabs represent a group of aquatic arachnids, comparable to aquatic mites, breaking a long-standing paradigm in chelicerate evolution and altering previous interpretations of the ancestral transition to the terrestrial habitat. Future studies testing chelicerate relationships should approach the task with a sampling strategy where the monophyly of Arachnida is not held as the premise., (© The Author(s) 2019. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The acquisition of a novel function, or neofunctionalization, protects duplicated genes from redundancy and subsequent loss, and is a major force that drives adaptive evolution. Neofunctionalization has been inferred for many duplicated genes based on differences in regulation between the parental gene and its duplicate. However, only few studies actually link the new function of a duplicated gene to a novel morphological or physiological character of the organism. Here we show that the duplication of dachshund (dac) in arachnids (spiders and allies) is linked with the evolution of a novel leg segment, the patella. We have studied dac genes in two distantly related spider species, the entelegyne spider Parasteatoda tepidariorum and the haplogyne spider Pholcus phalangioides. Both species possess two paralogous dac genes that duplicated before the split between entelegyne and haplogyne spiders. In contrast to the evolutionarily highly conserved dac1, its duplicate dac2 is strongly expressed in the patella leg segment during embryogenesis in both species. Using parental RNA interference in P. tepidariorum we show that dac2 is required for the development of the patella segment. If dac2 function is impaired, then the patella is fused with the tibia into a single leg segment. Thus, removing the function of dac2 experimentally reverts P. tepidariorum leg morphology into a stage before the duplication of dac and the evolution of the patella segment. Our results indicate that the origin of the patella is the result of the duplication and subsequent neofunctionalization of dac in the arachnid lineage., (© The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The harvestmen Amilenus aurantiacus overwinter in diapause in hypogean habitats. The midgut diverticula have been studied microscopically (light microscopy, TEM) and biochemically (energy-storing compounds: lipids and glycogen) to analyze changes during this programmed starvation period. Throughout the investigated period, the epithelium of the midgut diverticula is composed of secretory cells, digestive cells and adipocytes. Additionally, after the middle of overwintering, the excretory cells appear, and two assemblages of secretory cells are present: the SC1 secretory cells are characterized by electron-dense cytoplasm with numerous protein granules, and the SC2 cells by an electron-lucent cytoplasm with fewer protein granules. The autophagic activity is observed from the middle of overwintering, indicating its vital role in providing nutrients during this non-feeding period. Lipids and glycogen are present in the midgut diverticula cells, except in the excretory cells. Measurements of the lipid droplet diameters and the lipid quantities yielded quite comparable information on their consumption. Lipids are gradually spent in both sexes, more rapidly in females, owing to ripening of the ovaries. Glycogen rates decrease towards the middle, and increase just before the end of overwintering, indicating that individuals are preparing for the epigean active ecophase., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Chelicerata represents one of the oldest groups of arthropods, with a fossil record extending to the Cambrian, and is sister group to the remaining extant arthropods, the mandibulates. Attempts to resolve the internal phylogeny of chelicerates have achieved little consensus, due to marked discord in both morphological and molecular hypotheses of chelicerate phylogeny. The monophyly of Arachnida, the terrestrial chelicerates, is generally accepted, but has garnered little support from molecular data, which have been limited either in breadth of taxonomic sampling or in depth of sequencing. To address the internal phylogeny of this group, we employed a phylogenomic approach, generating transcriptomic data for 17 species in combination with existing data, including two complete genomes. We analyzed multiple data sets containing up to 1,235,912 sites across 3,644 loci, using alternative approaches to optimization of matrix composition. Here, we show that phylogenetic signal for the monophyly of Arachnida is restricted to the 500 slowest-evolving genes in the data set. Accelerated evolutionary rates in Acariformes, Pseudoscorpiones, and Parasitiformes potentially engender long-branch attraction artifacts, yielding nonmonophyly of Arachnida with increasing support upon incrementing the number of concatenated genes. Mutually exclusive hypotheses are supported by locus groups of variable evolutionary rate, revealing significant conflicts in phylogenetic signal. Analyses of gene-tree discordance indicate marked incongruence in relationships among chelicerate orders, whereas derived relationships are demonstrably robust. Consistently recovered and supported relationships include the monophyly of Chelicerata, Euchelicerata, Tetrapulmonata, and all orders represented by multiple terminals. Relationships supported by subsets of slow-evolving genes include Ricinulei + Solifugae; a clade comprised of Ricinulei, Opiliones, and Solifugae; and a clade comprised of Tetrapulmonata, Scorpiones, and Pseudoscorpiones. We demonstrate that outgroup selection without regard for branch length distribution exacerbates long-branch attraction artifacts and does not mitigate gene-tree discordance, regardless of high gene representation for outgroups that are model organisms. Arachnopulmonata (new name) is proposed for the clade comprising Scorpiones + Tetrapulmonata (previously named Pulmonata)., (© The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Juvenile harvestmen Gyas annulatus overwinter in dormancy in hypogean habitats for 4-5 months. The ultrastructure of the autophagic structures in their midgut epithelium cells was studied by light microscopy, transmission electron microscopy (TEM) and immunofluorescence microscopy (IFM) during this non-feeding period. Before overwintering (November), autophagic structures were scarce. In the middle (January) and at the end of overwintering (March), phagophores, autophagosomes and autolysosomes were present in the cytoplasm of both the secretory and the digestive midgut epithelium cells, gradually increasing their abundance during overwintering. In addition, vacuolization of the cytoplasm intensified. Both processes are induced by starvation. Autophagic structures and cytoplasm vacuolization enable the reuse of the cell's own components required for the maintenance of vital processes during dormancy. While TEM is a much more convenient method for recognition of the autophagic structure types and their ultrastructure, IFM enables exact counting of these structures., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Harvester species exhibit a diverse array of defenses against predators. In this article, we briefly cover chemical defenses, coloration patterns, autotomy, aggregations, freezing behavior, bobbing, body vibration, and the production of sounds that might be used to avoid predators' attacks. Those defenses are not present in all harvester species and may not deter all kinds of predators. We discuss how prey-predator interaction may shape the evolution of defenses. Here we focus on studies that have been done after 2007, and we aim to give a general idea of the knowledge about prey-predator interactions in Opiliones to date, especially to the general public. [ABSTRACT FROM AUTHOR]

A checklist of spiders from Kashmir, India, is provided which indicates the occurrence of 185 species under 100 genera and 25 families. The checklist is based primarily on the published records of spiders of Kashmir from 1885 to 2023 (up to January). These faunistic records reveal that the most diverse spider families in this region are Salticidae, Linyphiidae, Araneidae, Gnaphosidae, Thomisidae, Lycosidae and Theridiidae while about 11 families (Cheiracanthiidae, Clubionidae, Ctenidae, Filistatidae, Liocranidae, Mimetidae, Oxyopidae, Pimoidae, Scytodidae, Sicariidae and Uloboridae) are represented by a lone genus. The checklist includes taxa that have been identified upto species level. This checklist compiles the available regional faunistic records to serve future research. [ABSTRACT FROM AUTHOR]

Urban landscapes restrain the distribution of forest‐dwelling species, which may be related to challenging conditions that impair body condition. The dynamics in urban areas lead to the simplification of communities that inhabit forest patches in cities with the turnover of sensitive species for opportunistic ones. In this study, we investigated the effect of urbanization on the body condition and diversity of scorpions at the landscape scale. Sampling was carried out in 10 forest patches in an urban matrix in Brazil, originally covered by a tropical rainforest. The surroundings of the landscape of each forest patch were characterized through the amount of forest, agriculture, and urban land cover. Individual body length, dry, lipid, and muscular masses were used as proxies of Tityus pusillus body condition. In total, 147 scorpions were collected, belonging to the species Ananteris mauryi, T. pusillus, T. stigmurus, and T. neglectus. Forest cover explained 28% of species variation. There was a positive relationship between forest cover and T. pusillus and A. mauryi abundances, while T. stigmurus was negatively affected by forest cover. Species richness and total scorpion abundance were not influenced by landscape metrics. In terms of body condition, only females of T. pusillus were affected by landscape variables, with individuals showing higher body mass with an increase in forest cover. Our results suggest that urban forests can support scorpion assemblages. However, there is a turnover in specialist forest species for opportunistic species. Forest cover is a crucial factor in maintaining healthy scorpion populations in urban areas. [ABSTRACT FROM AUTHOR]

Small species often fall prey to a wide range of predators in their natural habitats, and therefore require behavioural strategies to mitigate predation rates. In this study, we investigated the defensive behaviour of Ananteris mauryi , a small-bodied scorpion, against different natural predator species. Behavioural trials were conducted with A. mauryi individuals facing two different predators, spider and scorpion. Our results show that A. mauryi altered their defensive acts depending on the predator type, swinging their telson, cleaning their pedipalps, and run more frequently when facing spiders than scorpions. Additionally, we observed variation in the duration of behaviours according to predator type, with stinging attempts being performed more frequently against scorpions and run and metasoma swinging against spiders. Our findings suggest that scorpions have the ability to modulate their defensive behaviour according to the type of predator they face. [ABSTRACT FROM AUTHOR]

Previous neoichnological studies with arthropods, especially arachnids, have often conducted experiments with only a small number of trackways produced in a subset of subaerial conditions. Thus, we conducted a comprehensive neoichnological study of scorpions (Hadrurus arizonensis), tarantulas (Grammostola rosea), and crayfish (Procambarus clarkii), under various moisture levels (dry, damp, wet drying, wet saturated, and subaqueous [or wading]) and horizontal, shallow, and steep slope angles. The invertebrates made a total of 473 trackway runs resulting in 489 symmetric trackway segments that were characterized and digitally measured. We analyzed the trackways using trackway parameter trend diagrams and non-metric multidimensional scaling (N-MDS) visualizations to compare trackway morphology among the sand moisture conditions. Results generally show imprints become progressively smaller, with more dotted multifid imprints going from loose to stiff sand. N-MDS showed trackway morphology overlapped among some conditions, including those with disparate water content (e.g. dry and wet saturated sand, or subaqueous and wet drying sand). Additionally, trackways consisted usually of a four-imprint series, though species- and condition-specific exceptions were found. Interestingly, the scorpions rarely dragged their metasomas, while the crayfish always dragged their tail fan except sometimes underwater. Our neoichnological photos and quantitative dataset provide a basis for future comparative ichnological studies. [ABSTRACT FROM AUTHOR]

Fire is an important disturbance factor in shrublands, grasslands, and savannas. It alters the habitat of a multitude of species and, under natural dynamics, is a major determinant of landscape vegetation patterns. Here, we evaluate the effects of different wildfire regimes on the abundance of sun spiders in the Cerrado-Pantanal ecotone. To study how different fire regimes affect the number of individual sun spiders, we considered the frequency of fire occurrences in the last 20 years and classified locations as high frequency or low frequency. We also classified the time of the last fire in 2020 as occurring in the first or second half of the year. In addition, we compared the number of individual sun spiders before and after fire. We found no effects of fire frequency and period when the fire occurred in 2020, but the number of individual sun spiders was higher after wildfires. Although ground-dwelling are considered fire sensitive, some can employ strategies to tolerate fire so that they are able to not only survive, but also reproduce in fire-prone landscapes. Thus, we suggest that sun spiders are resilient, can explore sites under different fire regimes, and can be considered pyrophilous species. [ABSTRACT FROM AUTHOR]

We evaluated the effect of different ecological factors on epigeic harvestmen (Opiliones) in stands of Norway spruce of different ages planted on former agricultural land in the Western Carpathians (Slovakia). In total, 15 species of harvestmen were recorded, which is 42.9% of the 35 species of harvestmen currently recorded in Slovakia. The most abundant species were Nelima sempronii, Lacinius ephippiatus, Mitopus morio, Oligolophus tridens, Leiobunum gracile and Platybunus bucephalus. Species richness and diversity was not associated with any forest characteristic. There was a negative association between the percentage of Norway spruce and abundance of harvestmen and positive association between the chemical element Ca2+ and harvestmen abundance. Beta diversity of harvestmen assemblages was low. Composition of harvestmen assemblages was significantly related to percentage of spruce, humus content, Ca2+, C/N and soil pH. Lacinius ephippiatus was most abundant in pitfall traps with a low percentage of spruce, Oligolophus tridens plots where there was low humus content and Leiobunum gracile tended to be more abundant in plots with more alkaline soils. [ABSTRACT FROM AUTHOR]

Understanding the effects of environmental conditions on biodiversity may provide cues regarding the resilience of ecological communities facing human activities in tropical forests. Under this scenario, harvestmen are among the most ideal models for understanding the ecological dynamics associated with shifts in environmental conditions. In this study, we evaluated how changes in attributes related to environmental conditions shape harvestmen assemblages in the Atlantic Forest. We assessed the effect of environmental transformation in four forest fragments with different proportions of native forest cover based on their environmental attributes (temperature, humidity, leaf litter depth and cover, and herbaceous vegetation cover) on harvestmen species richness, abundance, and composition. Overall, 865 harvestmen individuals belonging to six families and 41 species were sampled. The effects of environmental conditions on harvestmen assemblages were context‐dependent. In the most conserved fragment, there was an increase in harvestmen richness and abundance with increasing temperature. Furthermore, herbaceous vegetation cover negatively affected harvestmen richness and abundance. Species turnover was the main driver of harvestmen beta diversity in all forest fragments. With the results presented herein, we demonstrate that harvestmen species richness and abundance are modulated by landscape modifications and subsequent alterations in the environment resulting from human‐induced disturbance. Our results highlight the importance of considering environmental transformations at a large spatial scale (i.e., landscape) and local scale (i.e., environmental attributes) to design appropriate conservation strategies for Brazilian Atlantic Forest. [ABSTRACT FROM AUTHOR]

Long-branch attraction is a systematic artifact that results in erroneous groupings of fast-evolving taxa. The combination of short, deep internodes in tandem with long-branch attraction artifacts has produced empirically intractable parts of the Tree of Life. One such group is the arthropod subphylum Chelicerata, whose backbone phylogeny has remained unstable despite improvements in phylogenetic methods and genome-scale data sets. Pseudoscorpion placement is particularly variable across data sets and analytical frameworks, with this group either clustering with other long-branch orders or with Arachnopulmonata (scorpions and tetrapulmonates). To surmount long-branch attraction, we investigated the effect of taxonomic sampling via sequential deletion of basally branching pseudoscorpion superfamilies, as well as varying gene occupancy thresholds in supermatrices. We show that concatenated supermatrices and coalescent-based summary species tree approaches support a sister group relationship of pseudoscorpions and scorpions, when more of the basally branching taxa are sampled. Matrix completeness had demonstrably less influence on tree topology. As an external arbiter of phylogenetic placement, we leveraged the recent discovery of an ancient genome duplication in the common ancestor of Arachnopulmonata as a litmus test for competing hypotheses of pseudoscorpion relationships. We generated a high-quality developmental transcriptome and the first genome for pseudoscorpions to assess the incidence of arachnopulmonate-specific duplications (e.g. homeobox genes and miRNAs). Our results support the inclusion of pseudoscorpions in Arachnopulmonata (new definition), as the sister group of scorpions. Panscorpiones (new name) is proposed for the clade uniting Scorpiones and Pseudoscorpiones. [ABSTRACT FROM AUTHOR]

The first complete mitochondrial genome of the micro-whip-scorpion (Schizomus zhensis) was assembled from Illumina-based whole genome sequencing. The circular genome is 14,309 bp in length with 13 protein coding genes, 22 tRNA, 2 rRNAs, and a control region. The A + T content of the mitogenome is 76.6%. Maximum likelihood phylogenetic analyses placed Schizomus zhensis as a sister group of (Thelyphonida + Amblypygi), but more mitogenomes of Tetrapulmonata need to be included in further analyses for a conclusive decision about the group systematics. [ABSTRACT FROM AUTHOR]

The study of diversity has become increasingly sophisticated, including the use of measures of phylogenetic diversity.We calculate the spatial variation in species richness, taxonomic beta diversity, and alpha and beta phylogenetic diversity (PDα and PDβ, respectively) of Atlantic Forest harvestman communities using a data set containing 556 species from 68 sites, distributed in 12 Brazilian states.We compare the congruence of phylogenetic and taxonomic diversity patterns, and also compare PDα with null model expectations, to check for phylogenetic clustering or overdispersion in communities.Species richness and PDα are correlated, peaking in southern and south‐eastern coastal sites and decreasing towards the interior and towards the north‐east. PDα in north‐eastern sites was higher than expected, while a clustered phylogenetic pattern characterised most other sites.Communities in the southern and south‐eastern regions were dominated by species from the large family Gonyleptidae, presenting a high richness and a low PDα. As the dominance of Gonyleptidae decreased towards the north, where local communities have fewer species, but a higher PDα, they contain representatives of other families. The beta diversity was more sensitive to the compositional changes involving closely related Gonyleptidae species, while PDβ is more influenced by deeper phylogenetic compositional changes, between more distant lineages.Phylogenetic diversity may be of special importance to assess the conservation value of distantly related lineages. These species‐poor groups are less likely to influence taxonomic‐based diversity analyses, but their importance for conservation arises from their phylogenetic distinctiveness, captured by PDα and PDβ measures. [ABSTRACT FROM AUTHOR]

Copyright of Revista Biológico Agropecuaria Tuxpan is the property of Revista Biologico Agropecuaria Tuxpan 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.)

Scorpions (Arachnida: Scorpiones Koch, 1837) are an ancient chelicerate arthropod lineage characterised by distinctive subdivision of the opisthosoma and venomous toxicity. The crown group is represented by over 2400 extant species, and unambiguous fossil representatives are known at least from the Cretaceous Period. However, a number of extinct scorpion lineages existed in the Palaeozoic Era, many of which are of a contentious marine (or at least semi-aquatic) lifestyle, and have long caused confusion regarding the nature of arachnid terrestrialization and arachnid phylogeny more broadly. To clarify the process of terrestrialization, there is a need to marry fossil and extant scorpions in a common evolutionary framework utilising modern advances in phylogenetics. Here, we review phylogenetic hypotheses of arachnid and scorpion interrelationships, relevant advances in phylogenetic divergence time estimation and the scorpion fossil record—especially with reference to terrestrialization. In addition, we provide a list of scorpion fossil calibrations for use in molecular dating and demonstrate their utility in deriving a novel scorpion time tree using Bayesian relaxed-clock methods. Our results reveal a window of divergence from 335 to 266 Mya for the scorpion crown group, consistent with a Pangean origin of crown scorpions inferred from the biogeographical distribution of the extant fauna. [ABSTRACT FROM AUTHOR]

Mite harvestmen of the family Neogoveidae have a tropical trans-Atlantic distribution with representatives in equatorial West Africa and the Neotropics, specifically in the south-east region of the USA and in northern South America, being conspicuously absent from Central America. We provide a comprehensive molecular phylogeny of the family including representatives of all genera but the monotypic Tucanogovea Karaman, 2013, and new information on the type species described by Jochen Martens in 1969 that were unavailable for molecular study until now: Brasiliogovea microphaga , Metagovea oviformis and '? Gen. enigmaticus '. Additionally, we revisit the somatic and male genitalic morphology of representatives of all genera by means of scanning electron microscopy and confocal laser scanning microscopy, and describe the new genera Leggogovia Benavides & Giribet, gen. nov., Microgovia Benavides, Hormiga & Giribet, gen. nov., Waiwaigovia Benavides, Hormiga & Giribet, gen. nov. and 13 new species: Brasiliogovea aphantostylus Benavides, Hormiga & Giribet, sp. nov., Brasiliogovea microstylus Benavides, Hormiga & Giribet, sp. nov., Brasiliogovea yacambuensis Benavides, Hormiga & Giribet, sp. nov., Metagovea matapi Benavides, Hormiga & Giribet, sp. nov., Metagovea planada Benavides, Hormiga & Giribet, sp. nov., Microgovia chenepau Benavides, Hormiga & Giribet, sp. nov., Neogovea branstetteri Benavides, Hormiga & Giribet, sp. nov., Neogovea enigmatica Martens, sp. nov., Neogovea matawai Benavides, Hormiga & Giribet, sp. nov., Parogovia montealensis Benavides & Giribet, sp. nov., Parogovia prietoi Benavides & Giribet, sp. nov., Parogovia putnami Benavides & Giribet, sp. nov. and Waiwaigovia schultzi Benavides, Hormiga & Giribet, sp. nov. Phylogenetic analyses based on maximum likelihood, parsimony and Bayesian inference support the monophyly of Neogoveidae and a sister group relationship of Neogoveidae + Ogoveidae with Troglosironidae (a clade named Sternophthalmi). Relationships among neogoveid genera are largely congruent between methods as follows: ((Leggogovia gen. nov., Metasiro), (Parogovia , ((Canga , Microgovia gen. nov.), ((Brasiliogovea , Neogovea), (Huitaca , (Waiwaigovia gen. nov., Metagovea)))))). In light of our results, the following taxonomic changes are proposed: Metagovea oviformis Martens, 1969 is transferred to Microgovia , gen. nov.; Parogovia pabsgarnoni Legg, 1990 is transferred to Leggogovia , gen. nov.; '? Gen. enigmaticus Martens, 1969' is an invalid name according to the ICZN; the corresponding taxon is redescribed and formally named as Neogovea enigmatica Martens, sp. nov. A main impediment of biodiversity studies is the lack of accurate data on species numbers. Here we study the whole diversity of a family of mite harvestmen found in the tropics at both sides of the Atlantic, describe three new genera and 13 new species and present a comprehensive phylogeny of the group. Our results provide new insights into the biogeography of Neogoveidae and illustrate the need for careful taxonomic work in small soil animals. [ABSTRACT FROM AUTHOR]

The seasonal appearance of Tegenaria and Eratigena (the best known of the UK genera termed house spiders) results in considerable public and media interest. Here, we present the largest dataset ever gathered on the occurrence of house spiders anywhere in the world. We collected almost 10,000 records from different locations within the UK (amounting to ∼250× more locations and 25× more records than any previous study) over a six-month period. Using this dataset, which contained details of sighting dates, times, location within UK, location within the home, location within rooms, and sex, we were able to investigate a number of aspects of house spider ecology. Eightytwo percent of records were males, supporting previous studies that showed house spider surges in autumn are predominantly males seeking mates. Sightings peaked in mid-September with a significant northwest progression across the UK as autumn progressed. Daily activity peaked at 19.35 hrs and spiders were seen more or less uniformly throughout different rooms; we discuss why this is more likely to be due to spider ecology than human behaviour. Within rooms, there was a sex-based difference in ecology with females more common on ceilings and doors/windows and males more common on walls, possibly because of sex-specific differences in mobility. [ABSTRACT FROM AUTHOR]

Mygalomorph spiders are rarely found in caves and most of the records appear as accidental or restricted to small populations. The present study took place in iron formations in Carajás region, southeastern Pará state, eastern Brazilian Amazon rainforest. Each cave was sampled twice: dry season (from May to October) and wet season (from November to April). Of the 242 caves sampled, we found mygalomorphs in 98 (40%). The survey yielded 254 specimens, 223 (87.8%) juveniles. Of the 14 species recorded, nine were represented by adults:Dolichothele tucuruiense(Guadanucci, 2007),Hapalopus aymaraPerdomo, Panzera & Pérez-Miles, 2009,Acanthoscurria geniculata(CL Koch, 1841),Theraphosa blondi(Latreille, 1804),Nhandu coloratovillosus(Schmidt, 1998),Fufius minusculusOrtega, Nagahama, Motta & Bertani, 2013, and three new are species described here:Guyruita metallophilan. sp.,Hapalopus serrapeladan. sp., andIdiops carajasn. sp. Five other “morphospecies” were represented by juveniles only:Ummidiasp. (Ctenizidae),Paratropissp. (Paratropididae),Bolostromussp. (Cyrtaucheniidae),Diplurasp. (Dipluridae), andIdiophtalmasp. (Barychelidae). The high number of juveniles suggests two alternatives: some species could be using the hypogean environment as reproductive shelter; the hypogean environment is used as a refuge by immatures. Two species appear to be troglophiles:G. metallophilaandH. aymara. https://zoobank.org/urn:lsid:zoobank.org:pub:C92F29CB-4B9C-402D-8AA6-F8251DE49529. [ABSTRACT FROM PUBLISHER]

Egg attendance is the most common and phylogenetically widespread form of post-ovipositional care among ectotherms. The main benefit of egg attendance is to enhance offspring survival by preventing or attenuating attacks from natural enemies. In arachnids, there are few experimental studies on the benefits of egg attendance, and they pertain to species living in few types of habitats, mainly forests. To understand how the benefits of egg attendance vary in large geographical scales, we need to include species from poorly explored habitats, such as caves. Here, we describe a case of maternal egg attendance in an exclusive cave-dwelling harvestman, Phalangodus briareos. Using a parent removal experiment, we also assessed the benefits of egg attendance. We found that egg attendance improves egg survival because unattended clutches were almost entirely consumed by conspecifics and crickets. When females were maintained on their clutches, egg survival was always high, regardless of female body size. There was a positive effect of clutch size on egg predation, which was higher during nighttime. We suggest that larger clutches emit more chemical cues, attracting more predators in the cave habitat. Finally, we argue that the benefits of egg protection should be higher inside caves when compared to external habitats because food is scarce inside caves and the fauna consists mainly of predators and detritivores. [ABSTRACT FROM AUTHOR]

Currently, new antimicrobial molecules extracted or obtained by natural sources, could be a valide alternative to traditional antibiotics. Most of these molecules are represented by antimicrobial peptides (AMPs), which are essential compounds of insect, arachnids and centipedes venom. AMPs, due to their strong effectiveness, low resistance rates and peculiar mode of action, seem to have all the suitable features to be a powerful weapon against several bacteria, especially considering the increasing antibiotic-resistance phenomena. The present literature review focuses on the antibacterial activity of bee, wasp, ant, scorpion, spider and scolopendra crude venom and of their main biological active compounds. After a brief overview of each animal and venom use in folkloristic medicine, this review reports, in a comprehensive table, the results obtained by the most relevant and recent researches carried out on the antibacterial activity of different venom and their AMPs. For each considered study, the table summarizes data concerning minimal inhibitory concentration values, minimal bactericidal concentration values, the methods employed, scientific name and common names and provenience of animal species from which the crude venom and its respective compounds were obtained. [ABSTRACT FROM AUTHOR]

In nature conservation, providing new, advanced knowledge of protected habitats and biota often requires extensive sampling, which contradicts the main goal of minimizing damage and disturbance. How to avoid this innate collision was the main concern in our study. Highland habitats are suitable for addressing this problem, since they are relatively species-poor and therefore easier to analyze. Invertebrate distributions are, to some extent, expected to vary congruently with habitat type (HT) distributions. However, studies of such effects are scarce. In this study we researched harvestmen (Opiliones) in highland habitats above 1,800 m in the Kamnik-Savinja Alps, a Natura 2000 area in Slovenia. The question was whether mapping of HT distributions could predict the presence of the harvestman species and replace their laborious mapping. For this purpose, we studied relationships between the HT distributions and the harvestman species distributions with respect to environmental conditions. Chao2 and Jackknife1 were found to provide the best estimates of total species diversity. In assessing the species richness, the incidence-based approach was applied. No indicator harvestman species for the HTs, and no statistical difference was found in the harvestman community structure of three most frequently inhabited HTs. Most HTs and harvestman species responded gradually and in parallel to the changing environmental conditions along the altitudinal gradient, revealing covariation of their distributions. Hence, knowledge of highland HT distributions cannot replace the mapping of harvestmen. [ABSTRACT FROM AUTHOR]

Intra- and interspecific coexistence has been recorded in several species of scorpions, reflecting different levels of aggregation and sociability. Some species of scorpions avoid temporal or spatial overlap of their surface activities, which may differ depending on species, age group or gender, and thus reduce intra- and interspecific competition and predation. We examined the surface activity of males, females and juveniles (sex-age class) of the scorpion Brachistosternus ferrugineus (Thorell, 1876) in an area of Arid Chaco, and also its microhabitat preference and behavior by each sex-age class. The month-by-month activity of each sex-age class was different, but all the classes were observed each month. The most frequently used microhabitat was soil (64.8%), while leaf litter and vegetation were used in similar proportions. The behavior most frequently observed was ambush (68.3%), followed by walking and less frequently feeding, doorkeeping and courting. Each sex-age class performed one particular behavior with more frequency than the others. Analyzing combinations of microhabitat, behavior and sex-age class, we found the juveniles were associated with feeding on vegetation, males with walking on leaf litter, while females were related to ambush on soil. No marked temporal distribution between sex-age classes was observed. However, the spatial distribution and frequency of behaviors were highly dependent on developmental stage and sex. These differences may facilitate understanding of the coexistence of different age-sex classes of B. ferrugineus. [ABSTRACT FROM AUTHOR]

Two new species of harvestman (Opiliones: Neopilionidae: Enantiobuninae) are described from the Waitomo region of the North Island, New Zealand, Forsteropsalis bona sp. n. and F. photophaga sp. n. Both have been collected within caves in the region, where predation on glow-worms Arachnocampa luminosa has been previously recorded for one or both species (misidentified as 'Megalopsalis tumida'). However, both are regarded as troglophiles rather than strict troglobites due to the presence of specimens outside the cave systems, and the absence of troglobitic adaptations. Megalopsalis tumida (Forster, 1944) is identified as a junior synonym of Forsteropsalis fabulosa (Phillipps & Grimmett, 1932). [ABSTRACT FROM AUTHOR]

Ad hoc collections of spiders were made in August and early September 2003 and pitfall trap collections were conducted from June to October in 2004 and 2005 in southern Labrador. These collections represent the first systematic spider sampling for the most easterly area of mainland Canada. In total, 161 species in 15 families were identified to genus and species and 16 were indeterminate. Of the identified species, 89 were new records for Labrador and, of those, 16 species were new records for the province. In total, 94 species (58.4%) have Nearctic distributions and 67 species (41.6%) are Holarctic. No Palearctic species were found. Our study brings the number of spider species recorded in the province of Newfoundland and Labrador to 377 (213 in Labrador). [ABSTRACT FROM AUTHOR]

Phalangium opilio is the most widespread and one of the most common harvestman species in anthropogenic environments. A preliminary field experiment was carried out in Slovenia testing its preferences for different substrates. A two metres high rectangular tower with walls constituted of vertical bands of concrete, twice fired tile, wood and styrofoam was placed in a meadow. The wood proved to be the most suitable substrate, providing the most stable temperatures and moisture levels in comparison with the other experimental materials. In anthropogenic environment, various available substrates in microhabitats of Ph. opilio considerably contribute to a fine regulation of searching relatively thermally and moist-stable resting sites.

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia 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.)

Changes in arthropod fauna assemblages after different goat grazing treatments (breeds and stocking rates) and responses to grazing cessation were studied in a heath-gorse shrubland located in northern Spain, Three treatments (low grazing pressure and high grazing pressure with Cashmere breed and high grazing pressure with local Celtiberic breed) with three replicates were randomly allocated to nine plots. Fauna data were collected three times per year during 3 grazing yr (2003,2004, and 2005) and three times during 2007, i.e., 2 yr after grazing cessation. Arthropods were collected by 12 pitfall traps per plot, whereas vegetation cover and height were estimated by 100 random contacts per plot. Arthropod community composition was mostly affected by sampling year during the grazing period (between 2003 and 2005) but also between 2005 and 2007 (after cessation). Species composition differed between treatments, although the differences were not attributed to the stocking rates or to the goat breeds along those periods. Differences between treatments remained constant from 2003 to 2005 and between 2005 and 2007. Heather height explained most of the variance in arthropod species data during the last grazing year (2005), whereas heather cover was the most explanatory environmental variable 2 yr after grazing cessation (2007). Grazing effects still remained on both vegetation and fauna 2 yr after grazing cessation. [ABSTRACT FROM AUTHOR]

We present a general review of the knowledge on Mexican terrestrial arthropods and a set of hypotheses to help explain their biogeographic complexity, translated into biogeographic regions, dominions, provinces, and panbiogeographic nodes. Two biogeographic regions (Nearctic and Neotropical) and one transition zone are recognized. Within them, five dominions (Californian Nearctic, Continental Nearctic, Mexican Mountain, Antillean, and Mesoamerican) and 14 provinces (California, Baja California, Sonora, Mexican Plateau, Tamaulipas, Sierra Madre Occidental, Sierra Madre Oriental, Transmexican Volcanic Belt, Balsas Basin, Sierra Madre del Sur, Yucatán Peninsula, Mexican Gulf, Mexican Pacific Coast, and Chiapas) are recognized. Fifteen geographic areas where three different biogeographic provinces intersect are considered panbiogeographic nodes: California Norte, Sonora, Sonora-Chihuahua-Sinaloa, Jalisco-Nayarit, Jalisco-Zacatecas, Monterrey (Nuevo León), Ciudad Victoria (Tamaulipas), northwestern Michoacán, northern (Guerrero, Hidalgo-Puebla, Orizaba-Córdoba (Veracruz), Huajuapan de León (Oaxaca), Sierra de Juárez (Oaxaca), southern Oaxaca, and El Ocote (Chiapas). The Mexican Transition Zone presents the highest level of biotic mixture between Nearctic and Neotropical elements. Species distributed in the lowlands near the Mexican coasts have mostly Neotropical affinities, and can be detected further north than previously hypothesized. Nodes possess a higher biodiversity, with different biogeographic affinities. Some of them are currently under protection for their high biodiversity. None of them has been studied adequately, and future research will be very important to select more sites with high biodiversity, and species representing different lineages and biogeographic histories. [ABSTRACT FROM AUTHOR]

1. Spatial subsidies, defined as the flow of energy, nutrients, organisms or pollutants from one habitat to another, have been shown to affect the food–web dynamics in a wide range of ecosystems. An important subsidy to riparian communities is the contribution of adult stream insects to terrestrial predators such as birds, bats and lizards, but also invertebrates including ground and web-building spiders. 2. We surveyed 37 first- and second-order forest streams across differing environmental gradients in the Central South Island, New Zealand, to investigate the relationship between potential aquatic prey subsidies and predatory riparian arachnids. We anticipated that stream-insect biomass would be positively associated with riparian arachnids, as a result of emergent adult aquatic insect subsidies to the adjacent habitat. 3. We confirmed positive associations between stream-insect biomass as a predictor variable and riparian arachnid biomass ( R2 = 0.42, F1,34 = 25.2, P < 0.001) and web densities ( R2 = 0.45, F1,14 = 11.5, P < 0.01) respectively as dependent variables after adjusting for the confounding effects of environmental variables. Hierarchical partitioning confirmed the importance of stream insect biomass as a statistically significant contributor to the total explained variance in analyses calculated for arachnid biomass, abundance and web density. 4. A concurrent survey of spider-web density along 20-m transects from the stream edge into the forest indicated a strong decline in web-building spider density moving away from the stream ( R2 = 0.41, F1,158 = 109, P < 0.001), with stream-insect biomass as a significant covariate ( F1,149 = 17.7, P < 0.001). 5. Our results suggest that productivity gradients present in the donor system affect the magnitude of the interaction between adjacent habitats. Productivity gradients may lead to increased reciprocal subsidies through a positive feedback loop involving the predation of spiders and other predatory terrestrial invertebrates by aquatic predators. However, terrestrial insectivores such as birds, bats and lizards that are not readily used as prey by aquatic predators may circumvent the feedback cycle by consuming a large proportion of emergent aquatic-insect biomass. This may lead to asymmetry in the strength of food–web linkages between aquatic and terrestrial habitats. [ABSTRACT FROM AUTHOR]

1. Fields such as ecology, macroecology, and conservation biology rely on accurate and comparable data. This is especially important for mostly unknown and megadiverse taxa such as spiders and regions such as the Mediterranean. Short-term sampling programmes are increasingly seen as the best option for sampling spiders. Comparability of results, however, demands standard procedures both in methodology and in sampling period. Cost-efficiency dictates that this period should be the most species rich. 2. Pitfall trapping was conducted in 23 sites from north to south Portugal, comprising three large-scale environmental zones and many different habitat types, during 10 months in each site. The annual richness pattern, differences in this pattern between areas and habitats, the complementarity between sampling periods and possible environmental correlates of richness were studied. 3. May and June present the optimal time for collecting spiders in Mediterranean areas. Northern areas have a later peak in richness and dense tree-cover sites offer more flexibility for sampling, with a higher proportion of species present at each period throughout the year. 4. Day length is the environmental factor most correlated with species richness. Maximum daily temperature may reduce richness, especially in southernmost areas, where summer temperatures can be extremely harsh. 5. It is recommended that short-term sampling programmes, intended to give a reasonable picture of spider communities in Portugal and in the Iberian Peninsula (and possibly extending to all the Mediterranean), should be conducted during May or June, with variable flexibility according to area and habitat. The proposed suggestions should appeal to everyone working in the field, given the cost-efficiency and comparability of results by adopting a common standardised approach. [ABSTRACT FROM AUTHOR]

Despite the importance of considering arthropods in monitoring programs and conservation planning given their diversity in terrestrial ecosystems and potential in revealing environmental disturbances, most studies on the effects of habitat disturbances in tropical forests focused on vertebrates, plants and a few arthropod groups. By sampling 16 sites evenly distributed in four habitat categories (continuous mature and secondary forest and large and small secondary forest fragments), we investigated how harvestmen (Opiliones), which represent the third largest order of arachnids and have been poorly studied in tropical forests, are affected by habitat quality and quantity. Richness and abundance of rare species were strongly affected by habitat quality (first axis of principal component analysis on forest structure), increasing in less disturbed/mature forests. Richness, total abundance, abundance of rare species and of one of the three common species were higher in continuous forest, while only total abundance differed between large and small fragments. Detrended correspondence analysis revealed that just one species increased in abundance in fragments, while several others were associated with continuous and/or mature forest and that harvestman composition did not vary between large and small fragments. Our results suggest that harvestmen (1) are strongly affected by habitat quality and quantity, probably because, compared to other arthropod groups, they are relatively uniform in some relevant biological aspects (nocturnal predators dependent on microclimatic conditions that present low vagility); (2) are probably more indicative of intermediate-level disturbances, given the absence of species associated with highly-disturbed areas. [Copyright &y& Elsevier]

Abstract: Arachnids have a venom apparatus and secrete a complex chemical mixture of low molecular mass organic molecules, enzymes and polypeptide neurotoxins designed to paralyze or kill their prey. Most of these toxins are specific for membrane voltage-gated sodium channels, although some may also target calcium or potassium channels and other membrane receptors. Scorpions and spiders have provided the greatest number of the neurotoxins studied so far, for which, a good number of primary and 3D structures have been obtained. Structural features, comprising a folding that determines a similar spatial distribution of charged and hydrophobic side chains of specific amino acids, are strikingly common among the toxins from spider and scorpion venoms. Such similarities are, in turn, the key feature to target and bind these proteins to ionic channels. The search for new insecticidal compounds, as well as the study of their modes of action, constitutes a current approach to rationally design novel insecticides. This goal tends to be more relevant if the resistance to the conventional chemical products is considered. A promising alternative seems to be the biotechnological approach using toxin-expressing recombinant baculovirus. Spider and scorpion toxins having insecticidal activity are reviewed here considering their structures, toxicities and action mechanisms in sodium channels of excitable membranes. [Copyright &y& Elsevier]

Abstract: Findings on hemolymph lipoproteins in the class Arachnida are reviewed in relation to their lipid and protein compositions, hydrated densities, the capacity of apoproteins to bind lipids, and the influence of xenobiotics on their structures and functionality. The occurrence of hemolymphatic lipoproteins in arachnids has been reported in species belonging to the orders Araneida, Scorpionida, Solpugida and Acarina. However, lipoproteins were properly characterized in only three species, Eurypelma californicum, Polybetes pythagoricus and Latrodectus mirabilis. Like insect and crustaceans the arachnids examined contain high density lipoproteins (HDLs) as predominant circulating lipoproteins. Although in most arachnids these particles resemble those of insect HDLs called “lipophorins”, in two arachnid species they differ from lipophorins in their apoproteins, total mass and lipid composition. The hemolymph of P. pythagoricus and L. mirabilis contains another HDL of higher density, while P. pythagoricus and E. californicum hemolymph contain a third lipoprotein of very high density (VHDL). Composition of arachnid lipoproteins regarding apoprotein classes as well as lipid classes differ among species. Hemocyanin, in addition to the classical role of this protein as respiratory pigment, is presented here performing the function of apolipoprotein in some arachnid species. Reports on experiments demonstrating the capacity of hemocyanin to bind neutral and polar lipid classes, including ecdysteroids, are commented. Recent works about the changes evoked by a phosphorous pesticide on the structures and functionality of spider lipoproteins are also reviewed. [Copyright &y& Elsevier]

The article presents the list of pseudoscorpions species or arachnids from Colombia. According to the authors, the known species in the country were recorded by foreign authors since 1800s, however, detailed information about each species were not recorded. In connection, researchers D. E. Florez and H. Sànchez published a preliminary list that established nine species distributed in nine genera and six families.

Abstract: Intra-specific variation in life history and mating strategies can lead to differences in energy allocation and expenditure in males and females. This may, in turn, explain large-scale evolutionary patterns. In this study, I investigated the effects of body mass, temperature and sex on resting metabolic rates (RMRs) in sexually mature male and female tarantulas (Aphonopelma anax (Chamberlin)), a species that exhibits extreme inter-sexual differences in life history after reaching sexual maturity. RMRs were measured as rates of CO2 production in an open-flow respirometry system at 20, 25, 30 and 35 °C. These temperatures are typical to what this species experiences under natural conditions. In addition, a respiratory quotient (RQ) of 0.92 was calculated from rates of CO2 production and O2 consumption in a closed, constant-volume respirometry system. As expected, RMRs increased with increasing temperature and body mass. However, after adjusting for the influence of body mass, males had substantially higher metabolic rates than females at each temperature. This higher metabolic rate is proposed as an adaptive strategy to support higher energetic demands for males during their active, locomotory search for females during the mating season. [Copyright &y& Elsevier]

Gyas annulatus and G. titanus (Arachnida: Opiliones: Phalangiidae) were studied comparatively with special interest in their hypogean ecophase. Direct comparisons were made in two caves where both species overwintered, and in the laboratory. Their chilling hardiness was tested, and the dynamics of lipid and glycogen stocks was studied. Juveniles overwinter inactive in physically unstable stone accumulations close to water currents, and in water- and wet caves. In caves, G. annulatus prefers colder microhabitats (at –0.1 to 2.1 °C) near the entrances and close to water surfaces while G. titanus prefers warmer ones (at 4.1–8.3 °C) deeper inside and much above the water. G. annulatus overwinters gregariously, profiting in this way from a collective sensing of sudden water rises, while G. titanus overwinters in a solitary manner. Neither Gyas species is cold hardy during overwintering (LT50 in both about –2 °C), while in post-overwintering specimens, a weak cold hardiness appears (in May LT50 in both between –3 and –4 °C) which helps them better withstand sudden summer chillings. During overwintering, G. annulatus spends about a quarter of the total energy, but twice as much glycogen as G. titanus; the captive G. annulatus spent 5.20 J g–1 dry mass day–1 from 0.122 lipids and 0.026 mg g–1 dry mass day–1 glycogen, and G. titanus 21.22 from 0.538 lipids and 0.014 glycogen, respectively. The general energy saving, excessive glycogen supply and overwintering gregariousness in G. annulatus reflect its optimal adaptation to preferred alpine habitats close to water current surfaces in the active ecophase, as well as during lasting overwintering. [Copyright &y& Elsevier]

Insects, arachnids, and other medically important arthropods affect human health directly by bites, stings, and blisters, and indirectly by disease transmission. In this paper, three widely divergent cases of insect- or arachnid-caused human illness are presented—a spider bite, a mosquito-borne disease case, and an imaginary mite problem. Some key references are included for each topic, as well as editorial comment to add perspective. [ABSTRACT FROM AUTHOR]

Sistema Huautla is the deepest cave system in the Americas at 1560 m and the fifth longest in Mexico at 89,000 m, and it is a mostly vertical network of interconnected passages. The surface landscape is rugged, ranging from 3500 to 2500 masl, intersected by streams and deep gorges. There are numerous dolinas, from hundreds to tens of meters in width and depth. The weather is basically temperate subhumid with summer rains. The average yearly rainfall is approximately 2500 mm, with a monthly average of 35 mm for the driest times of the year and up to 500 mm for the wettest month. All these conditions play an important role for achieving the highest terrestrial troglobite diversity in Mexico, containing a total of 35 species, of which 27 are possible troglobites (16 described), including numerous arachnids, millipedes, springtails, silverfish, and a single described species of beetles. With those numbers, Sistema Huautla is one of the richest cave systems in the world. [ABSTRACT FROM AUTHOR]

Allergic reactions following contact or injury from arachnids are uncommon. There have previously only been reports of urticarial reactions following contact with large spiders from the family Theraphosidae. A 55-year-old male presented to hospital with a generalised urticarial rash following contact with a spider, identified by the person as a huntsman spider (Family: Sparassidae). The spider had crawled over both his arms for a period of minutes. About 30 min later, he developed a rash on the arms which spread to the trunk. He then developed bradycardia and hypotension that required treatment with atropine, adrenaline and histamine antagonists. He recovered within 6 h and had no further problems. The early allergic reaction in this case was most likely the result of contact with the spider. [Copyright &y& Elsevier]