New taxonomic considerations in the spitting spider family Scytodidae (Arachnida: Araneae).

New taxonomic considerations in the spitting spider family Scytodidae Blackwall, 1864 are proposed. Here, the family is considered to include two subfamilies: Scytodinae Blackwall, 1864, comprising the genera Scytodes Latreille, 1804 and Dictis L. Koch, 1872, and Scyloxinae subfam. n., comprising the genera Scyloxes Dunin, 1992 and Stedocys Ono, 1995. Scytodes arwa Rheims, Brescovit van Harten, 2006 is considered a senior synonym of Scytodes makeda Rheims, Brescovit van Harten, 2006 syn. n. and the male of Scytodes kumonga Zamani Marusik, 2020 is described for the first time, with the species being newly recorded from Oman. Observations on the natural history of S. kumonga were made using specimens raised to maturity from egg-sacs produced by females collected in Oman. The monotypic genus Soeuria Saaristo, 1997 is synonymized with Dictis, hence the transfer of its type species, D. soeur (Saaristo, 1997) comb. n. to this genus. Dictis thailandica Dankittipakul Singtripop, 2010 is considered incertae sedis, and Dictis striatipes L. Koch, 1872 is considered a senior synonym of Dictis lugubris Thorell, 1887 syn. n., Scytodes bilqis Rheims, Brescovit van Harten syn. n., Dictis denticulata Dankittipakul Singtripop, 2010 syn. n., Dictis ganeshi Keswani, 2015 syn. n. and D. mumbaiensis Ahmed, Satan, Khalap Mohan, 2015 syn. n., and the species is newly reported from several countries. Scyloxes magna (Bristowe, 1952) comb. n. and Scyloxes zhaoi (Wu Li, 2017) comb. n. are transferred to Scyloxes from Scytodes and Stedocys, respectively.

Phylogeny and biogeography of the ancient spider family Filistatidae (Araneae) is consistent both with long-distance dispersal and vicariance following continental drift.

Filistatids, the crevice weavers, are an ancient family of cribellate spiders without extant close relatives. As one of the first lineages of araneomorph spiders, they present a complicated mixture of primitive and derived characters that make them a key taxon to elucidate the phylogeny of spiders, as well as the evolution of phenotypic characters in this group. Their moderate diversity (187 species in 19 genera) is distributed mainly in arid and semi-arid subtropical zones of all continents, except Antarctica. The objective of this paper is to generate a comprehensive phylogenetic hypothesis for this family to advance the understanding of its morphological evolution and biogeography, as well as lay the basis for a natural classification scheme. By studying the morphology using optical and electronic microscopy techniques, we produced a matrix of 302 morphological characters coded for a sample of 103 species of filistatids chosen to represent the phylogenetic diversity of the family. In addition, we included sequences of four molecular markers (COI, 16S, H3 and 28S; 3787 aligned positions) of 70 filistatid species. The analysis of the data (morphological, molecular, and combined) consistently indicates the separation of the Filistatidae into two subfamilies, Prithinae and Filistatinae, in addition to supporting several groups of genera: Filistata, Zaitunia and an undescribed genus from Madagascar; Sahastata and Kukulcania; all Prithinae except Filistatinella and Microfilistata; Antilloides and Filistatoides; a large Old World group including Pritha, Tricalamus, Afrofilistata, Labahitha, Yardiella, Wandella and putative new genera; and a South American group formed by Lihuelistata, Pikelinia and Misionella. Pholcoides is transferred to Filistatinae and Microfilistata is transferred to Prithinae, and each represents the sister group to the remaining genera of its own subfamily. Most genera are valid, although Pikelinia is paraphyletic with respect to Misionella, so we consider the two genera as synonyms and propose a few new generic combinations. Considering the new phylogenetic hypothesis, we discuss the evolution of some morphological character systems and the biogeography of the family. The ages of divergence between clades were estimated using a total-evidence tip-dating approach by including fossils of Filistatidae and early spider clades; this approach resulted in younger age estimates than those obtained with traditional node-dating. Filistatidae is an ancient family that started diversifying in the Mesozoic and most genera date to the Cretaceous. Clades displaying transcontinental distributions were most likely affected by continental drift, but at least one clade shows unequivocal signs of transoceanic long-distance dispersal.

Five-Year Monitoring of a Desert Burrow-Dwelling Spider Following an Environmental Disaster Indicates Long-Term Impacts.

Deserts are characterized by unpredictable precipitation and extreme temperatures. Their fauna and flora are sensitive to anthropogenic environmental changes, and often recover slowly from environmental disasters. The effects of oil spills on the biota of desert regions, however, have scarcely been studied. We predicted that terrestrial invertebrates suffer long-term negative effects from an oil spill, due to their close association with the substrate. Thus, we investigated the effects of two oil spills that occurred in 1975 and 2014 in the hyper-arid 'Arava desert (Israel), on a spider that constructs silk-lined nests in burrows in compact, sandy soil in this extreme desert habitat. The spider, Sahastata aravaensis sp. nov. (Filistatidae), is described herein. We assessed spider burrow abundance in plots located in oil-contaminated and nearby uncontaminated clean soil (control) areas over five consecutive years and measured habitat characteristics in these plots. In the laboratory, we determined the preference of individuals for clean vs. oil-contaminated soil as a resting substrate. Finally, as this species was previously undescribed, we added a new species description. The abundance of Sahastata was significantly lower in oil-contaminated plots, and this was the case in the 40-year-old oil spill (1975) as well as in the recent one (2014). In laboratory tests, spiders showed a significant preference for the clean soil substrate over the oil-contaminated substrate. In the field, soil crust hardness and vegetation density did not differ significantly between oil-contaminated and control plots, but these measures were highly variable. The burrows were significantly clustered, suggesting that the young disperse only short distances. In the laboratory adult spiders did not dig burrows, perhaps indicating that adults remain permanently in their natal burrows and that in the field they may use vacant burrows. We conclude that Sahastata populations were affected negatively by the oil spills and these effects were long-lasting. We propose that by monitoring their spatial distribution, burrow-dwelling spiders such as Sahastata can be used as effective bioindicators of soil pollution in desert habitats.

Sequence Capture Phylogenomics of True Spiders Reveals Convergent Evolution of Respiratory Systems.

The common ancestor of spiders likely used silk to line burrows or make simple webs, with specialized spinning organs and aerial webs originating with the evolution of the megadiverse "true spiders" (Araneomorphae). The base of the araneomorph tree also concentrates the greatest number of changes in respiratory structures, a character system whose evolution is still poorly understood, and that might be related to the evolution of silk glands. Emphasizing a dense sampling of multiple araneomorph lineages where tracheal systems likely originated, we gathered genomic-scale data and reconstructed a phylogeny of true spiders. This robust phylogenomic framework was used to conduct maximum likelihood and Bayesian character evolution analyses for respiratory systems, silk glands, and aerial webs, based on a combination of original and published data. Our results indicate that in true spiders, posterior book lungs were transformed into morphologically similar tracheal systems six times independently, after the evolution of novel silk gland systems and the origin of aerial webs. From these comparative data, we put forth a novel hypothesis that early-diverging web-building spiders were faced with new energetic demands for spinning, which prompted the evolution of similar tracheal systems via convergence; we also propose tests of predictions derived from this hypothesis.[Book lungs; discrete character evolution; respiratory systems; silk; spider web evolution; ultraconserved elements.].

Rectifying the identities of the males of two Micrathena species (Araneae: Araneidae), with report of the first case of intersexuality in the genus.

Despite extensive taxonomic work on the Neotropical fauna of the spider genus Micrathena Sundevall, for 27 out of 117 (23%) species only the female morphology has been described, and some of the previously hypothesized male-female matches have been proven erroneous. This work provides new insight about sex matching in two species: Micrathena ruschii (Mello-Leitão, 1945) and Micrathena lata Chickering, 1960. For Micrathena ruschii, the male previously hypothesized to belong to this species was collected with females in Itatiaia; we here present morphologically different males, also collected with females, in Macaé, both in Rio de Janeiro, Brazil. Through a DNA barcoding approach, we present molecular evidence indicating conspecificity of M. ruschii females with the males collected in Macaé, proving the male from Itatiaia to be a misidentification. Therefore, a description of the correct male of Micrathena ruschii is herein provided. The male previously identified as M. ruschii probably represents an undescribed species but is not named here due to scarcity of material. We also describe for the first time the male of Micrathena lata based on one specimen collected in Misiones, Argentina. This male specimen belongs to the militaris species group, where M. lata is the only species from the Atlantic Forest previously only known by females. In addition, we detect an intersexual specimen of Micrathena ruschii, revealing the first case of intersexuality for the genus.

On Sahastata (Araneae: Filistatidae): complementary description of the generotype and two new species from Oman and Morocco.

The Filistatinae genus Sahastata Benoit, 1968 is distributed in arid and semi-arid areas, from westernmost Sahara to India, and includes seven known species. Four of these are only known from one sex, including Sahastata nigra (Simon, 1897), the type species. Here we present the first description of a male of this species collected near the type locality in Muscat, Oman. Additionally, two new species are described: S. wunderlichi sp. nov. (♂♀, Morocco) and S. wesolowskae sp. nov. (♂♀, Oman). Sahastata infuscata (Kulczynski, 1901) is newly recorded from Kenya and Yemen and S. nigra is newly recorded from the United Arab Emirates. DNA barcodes are given for S. nigra and the two new species. We observed some details of the life cycle of three Sahastata species, including clutch size, time to maturation, and a biased sex ratio for individuals raised from egg sacs, indicating that only 20-25% of specimens reaching adulthood are males. We provide SEM images of spiders of this genus, some observations on the morphology of spinnerets and male palps, and a distribution map of the species included in the genus.

The fossil record of spiders revisited: implications for calibrating trees and evidence for a major faunal turnover since the Mesozoic.

Studies in evolutionary biology and biogeography increasingly rely on the estimation of dated phylogenetic trees using molecular clocks. In turn, the calibration of such clocks is critically dependent on external evidence (i.e. fossils) anchoring the ages of particular nodes to known absolute ages. In recent years, a plethora of new fossil spiders, especially from the Mesozoic, have been described, while the number of studies presenting dated spider phylogenies based on fossil calibrations increased sharply. We critically evaluate 44 of these studies, which collectively employed 67 unique fossils in 180 calibrations. Approximately 54% of these calibrations are problematic, particularly regarding unsupported assignment of fossils to extant clades (44%) and crown (rather than stem) dating (9%). Most of these cases result from an assumed equivalence between taxonomic placement of fossils and their phylogenetic position. To overcome this limitation, we extensively review the literature on fossil spiders, with a special focus on putative synapomorphies and the phylogenetic placement of fossil species with regard to their importance for calibrating higher taxa (families and above) in the spider tree of life. We provide a curated list including 41 key fossils intended to be a basis for future estimations of dated spider phylogenies. In a second step, we use a revised set of 23 calibrations to estimate a new dated spider tree of life based on transcriptomic data. The revised placement of key fossils and the new calibrated tree are used to resolve a long-standing debate in spider evolution - we tested whether there has been a major turnover in the spider fauna between the Mesozoic and Cenozoic. At least 17 (out of 117) extant families have been recorded from the Cretaceous, implying that at least 41 spider lineages in the family level or above crossed the Cretaeous-Paleogene (K-Pg) boundary. The putative phylogenetic affinities of families known only from the Mesozoic suggest that at least seven Cretaceous families appear to have no close living relatives and might represent extinct lineages. There is no unambiguous fossil evidence of the retrolateral tibial apophysis clade (RTA-clade) in the Mesozoic, although molecular clock analyses estimated the major lineages within this clade to be at least ∼100 million years old. Our review of the fossil record supports a major turnover showing that the spider faunas in the Mesozoic and the Cenozoic are very distinct at high taxonomic levels, with the Mesozoic dominated by Palpimanoidea and Synspermiata, while the Cenozoic is dominated by Araneoidea and RTA-clade spiders.

Spreadsheets to expedite taxonomic publications by automatic generation of morphological descriptions and specimen lists.

It is now generally accepted that we are going through a major mass extinction event that is causing biodiversity loss at alarming rates (Barnosky et al. 2011). We also know that many species remain to be formally described (e.g. Huber 2014), and concerns have been raised as to whether we will be able to document these before they go extinct (Costello et al. 2013). On one hand, the number of recognized species increases exponentially (e.g. Agnarsson et al. 2013; Sangster Luksenburg 2015). On the other, taxonomic descriptions are becoming more complete and detailed, which is necessarily more time-consuming, leading to an overall decline in the number of species described per taxonomist (Sangster Luksenburg 2015). In this scenario, any method or protocol that increases efficiency in taxonomic descriptions is welcome.

On chilean loxosceles (Araneae: Sicariidae): first description of the males of L. surca and L. coquimbo, new records of L. laeta and three remarkable new species from coastal deserts

Loxosceles Heineken & Lowe, 1832 spiders are infamous for their medical importance, but a taxonomic picture of the genus is still far from complete. In this study, the Chilean species of Loxosceles are described and mapped. The males of Loxosceles surca Gertsch, 1967 and L. coquimbo Gertsch, 1967 are described for the first time. Three new species with narrow distributions are described from central and northern Chile: Loxosceles diaguita sp. nov. from the Antofagasta Region, L. pallalla sp. nov. from Coquimbo and L. vallenar sp. nov. from Atacama. The first two species are remarkable in their morphology and do not fit into any of Gertsch’s species groups, suggesting that Chile still harbours an undiscovered phylogenetic diversity of the genus. New distribution records for Loxosceles laeta (Nicolet, 1849) are provided throughout Chile.

Phylogeny of Sicariidae spiders (Araneae: Haplogynae), with a monograph on Neotropical Sicarius

Sicariids are an infamous spider family containing two genera: the poorly known Sicarius Walckenaer and the medically important Loxosceles Heineken & Lowe. We present the first broad survey of the morphology of the family from a phylogenetic perspective in order to resolve its relationships. We scored morphological, behavioural and venom feature data for 38 taxa, including New and Old World species of both Sicarius and Loxosceles and three outgroups. Our results point to the monophyly of Sicariidae and its two genera as currently delimited, with the identification of novel synapomorphies for all of them. We present evidence of a group of 'true' Loxosceles composed of all members of the genus except those from the spinulosa species group. Sicarius have a very interesting phylogenetic structure, with species from the Americas and Africa forming reciprocally monophyletic groups. Thus, we resurrect Hexophthalma Karsch to accommodate African Sicariinae species. We discuss the evolution of venom proteins, spinning organs and cryptic appearance in Sicariidae. We delimit Sicarius to include only the 20 Neotropical species, and present a taxonomic revision of the genus. We redescribe nine previously known species, elevate one subspecies to species, and describe six new species from Argentina, Bolivia, Brazil and Peru. Sicarius levii sp. nov., from Argentina, is probably the largest known haplogyne spider in both body length and mass. Six specific names are considered junior synonyms of older names. All these species are illustrated and have their distributions mapped. We present an interactive key for identifying Sicarius species.

Three new species of Misionella from northern Brazil (Araneae, Haplogynae, Filistatidae).

Three new species of the genus Misionella are described from Brazil: Misionella carajas sp. n. and Misionella aikewara sp. n. from caves in the states of Pará and Tocantins and Misionella pallida sp. n. from natural and synanthropic dry areas in the states of Piauí, Maranhão, Rio Grande do Norte and Bahia. These species seem to belong to a distinct group within the genus; the males have an elongate palpal tibia and bulb, a pair of characteristic and hirsute macrosetae in the second metatarsus and the females have internal genitalia with only one pair of spermathecae, with relatively short ducts, lacking the auxiliary receptacles. Their phylogenetic placement and geographic distribution are briefly discussed.

Strong spatial structure, Pliocene diversification and cryptic diversity in the Neotropical dry forest spider Sicarius cariri.

The Brazilian Caatinga is part of the seasonally dry tropical forests, a vegetation type disjunctly distributed throughout the Neotropics. It has been suggested that during Pleistocene glacial periods, these dry forests had a continuous distribution, so that these climatic shifts may have acted as important driving forces of the Caatinga biota diversification. To address how these events affected the distribution of a dry forest species, we chose Sicarius cariri, a spider endemic to the Caatinga, as a model. We studied the phylogeography of one mitochondrial and one nuclear gene and reconstructed the paleodistribution of the species using modelling algorithms. We found two allopatric and deeply divergent clades within S. cariri, suggesting that this species as currently recognized might consist of more than one independently evolving lineage. Sicarius cariri populations are highly structured, with low haplotype sharing among localities, high fixation index and isolation by distance. Models of paleodistribution, Bayesian reconstructions and coalescent simulations suggest that this species experienced a reduction in its population size during glacial periods, rather than the expansion expected by previous hypotheses on the paleodistribution of dry forest taxa. In addition to that, major splits of intraspecific lineages of S. cariri took place in the Pliocene. Taken together, these results indicate S. cariri has a complex diversification history dating back to the Tertiary, suggesting the history of dry forest taxa may be significantly older than previously thought.

The six-eyed sand spiders of the genus Sicarius (Araneae: Haplogynae: Sicariidae) from the Brazilian Caatinga.

In this paper we revise the species of Sicarius (Araneae: Sicariidae) from the Brazilian Caatinga, the largest tropical dry forest nucleus in the world. We redescribe, designate a neotype and provide new records for Sicarius tropicus (Mello- Leitão, 1936), the only species previously known from the region, and describe three new species: S. cariri n. sp., S. diadorim n. sp. and S. ornatus n. sp. We report high intraspecific variation in the genitalic morphology of these species, especially in females. We also provide anecdotal observations on natural history and behavior of these species, including diet, mating behavior and clutch size. We include an identification key for Brazilian Caatinga species of Sicarius.

LAITOR--Literature Assistant for Identification of Terms co-Occurrences and Relationships.

BACKGROUND: Biological knowledge is represented in scientific literature that often describes the function of genes/proteins (bioentities) in terms of their interactions (biointeractions). Such bioentities are often related to biological concepts of interest that are specific of a determined research field. Therefore, the study of the current literature about a selected topic deposited in public databases, facilitates the generation of novel hypotheses associating a set of bioentities to a common context. RESULTS: We created a text mining system (LAITOR: Literature Assistant for Identification of Terms co-Occurrences and Relationships) that analyses co-occurrences of bioentities, biointeractions, and other biological terms in MEDLINE abstracts. The method accounts for the position of the co-occurring terms within sentences or abstracts. The system detected abstracts mentioning protein-protein interactions in a standard test (BioCreative II IAS test data) with a precision of 0.82-0.89 and a recall of 0.48-0.70. We illustrate the application of LAITOR to the detection of plant response genes in a dataset of 1000 abstracts relevant to the topic. CONCLUSIONS: Text mining tools combining the extraction of interacting bioentities and biological concepts with network displays can be helpful in developing reasonable hypotheses in different scientific backgrounds.