Solifugae Research Articles

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

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

Evaluating hypotheses for the function of the ‘hissing’ stridulation of sun spiders (Arachnida Solifugae)

Solifugae, also known commonly as sun spiders or camel spiders, are spider-like arachnid predators commonly present in desert and arid environments, though they also occur in forests and grasslands...

A test of the light attraction hypothesis in camel spiders of the Mojave Desert (Arachnida: Solifugae)

Research progress on the order Solifugae, commonly known as camel spiders, has been hindered by challenges inherent in collecting these fast-moving, nocturnal predators. Recently, pitfall trapping combined with artificial light lures showed promise for improving capture rates, but the hypothesis that camel spiders are attracted to light traps (positive phototaxis) has never been tested. We constructed short pitfall trap arrays with and without lights across the Mojave Desert to test the light attraction hypothesis. Nearly all camel spiders we collected were found in traps with suspended lights, lending strong support for positive phototaxis. Distance from the lights within trap arrays does not appear to be correlated with the success of individual pitfall traps. Excitingly, our short pitfall light arrays, or Caterpillar light traps, were relatively easy to install and yielded an order of magnitude more camel spiders per effort hour than previously reported techniques.

Primary processing neuropils associated with the malleoli of camel spiders (Arachnida, Solifugae): a re-evaluation of axonal pathways

BackgroundArachnids possess highly specialized and unorthodox sense organs, such as the unique pectines of Scorpiones and the malleoli of Solifugae. While the external morphology, numbers, and shapes of sensory organs are widely used in taxonomic studies, little is known about the internal anatomy of these organs and their associated processing neuropils in the central nervous system. Camel spiders (Solifugae) possess pedipalps and first walking legs heavily endowed with sensory structures, as well as conspicuous malleoli located ventrally on the proximal fourth walking legs. Malleoli are fan-shaped organs that contain tens of thousands of presumptive chemoreceptor neurons, but mechanoreceptive structures are absent.ResultsHere, we examine the organization of the synganglion based on microCT analysis, 3D reconstruction of serial paraffin sections, and backfill preparations to trace the malleolar pathway. The projection area of malleolar afferents is intriguingly located in the most anterior ventral nerve cord, located in between the pedipalpal neuromere hemispheres. However, malleolar axon bundles are separated by a thin soma layer that points to an anteriad projection of the fourth walking leg neuromere. A conspicuous projection neuron tract that may receive additional input from pedipalpal sensory organs connects the malleolar neuropil with the mushroom bodies in the protocerebrum.ConclusionArthropod chemosensory appendages or organs and primary processing neuropils are typically located in the same segment, which also holds true in Solifugae, although the malleolar neuropil is partially shifted towards the pedipalpal neuromere. A comparison of the malleoli in Solifugae and the pectines in Scorpiones, and of their primary processing neuropils, reveals certain similarities, while striking differences are also evident. Similarities include the ventral arrangement of peg-shaped sensory structures on the respective segmental appendage, exposing dense arrays of chemoreceptive sensilla, and projections to a primary processing neuropil with glomerular subdivision. Differences are, e.g., the lack of mechanoreceptive afferents and an associated processing neuropil.

New insights to the taxonomy of Rhagodes eylandti (Walter, 1889): A remarkable sexually dimorphic species (Solifugae: Rhagodidae).

The taxonomy of the widespread camel spider, Rhagodes eylandti (Walter, 1889), is herein updated and revised by proposing three nominal taxa as its junior synonyms. These are based on data from males of two taxa, Rhagodes melanopygus nigricans Birula, 1905 and R. plumbescens (Walter, 1889), and a female of R. melanochaetus Heymons, 1902. Consequently, both sexes of R. eylandti are re-described and the validity of their morphological diagnostic characters is evaluated. Detailed morphological and morphometrical characters, as well as data on sexual dimorphism and intraspecific variations, are provided. The illustrations of type material are given for the first time. Moreover, a distribution map and ecological notes are presented.

Influence of some abiotic factors on the activity patterns of trapdoor spiders, scorpions and camel spiders in a central South African grassland

Trapdoor spiders (Araneae: Mygalomorphae), scorpions (Scorpiones) and camel spiders (Solifugae) were collected by pitfall trapping from an undisturbed grassland area within the Free State National Botanical Gardens, with the aim of analysing the effects of rainfall, temperature and lunar incidence on their activity patterns. During the study a total of 8109 non-acarine arachnids were collected, of which Mygalomorphae, Solifugae and Scorpiones represented only 5.04% (n = 409). Mygalomorph spiders (n = 195) were represented by four families and five species, namely Ancylotrypa dreyeri (Hewitt, 1915) (Cyrtaucheniidae), Stasimopus oculatus Pocock, 1897 and S. minor Hewitt, 1915 (Ctenizidae), Segregara sylvestris (Hewitt, 1925) (Idiopidae) and Calommata meridionalis Fourie, Haddad and Jocqué, 2011 (Atypidae). Scorpions (n = 71) were represented by two buthid species, Uroplectes triangulifer (Thorell, 1876) and U. carinatus (Pocock, 1890). Solifugae (n = 153) were represented by Solpugema coquinae orangica (Hewitt, 1919) and Solpugassa sp. (Solpugidae). Rainfall and temperature were the main factors influencing seasonal variations in activity, with lunar incidence having no detectable effect. Uroplectes triangulifer and Solpugema coquinae orangica were the only species active during late winter and early spring, prior to the first significant rains in mid-spring. After emerging, populations of most species rapidly increased to a peak before declining again.

Food composition of Indian Eagle Owl Bubo bengalensis Franklin (Aves: Strigiformes: Strigidae) from Tiruchirappalli District, Tamil Nadu, India

The diet of the Indian Eagle Owl was studied from April to September 2017 in Tiruchirapalli District, Tamil Nadu, India. Analysis of 1082 regurgitated pellets yielded 2077 prey items; the mean prey items/ pellet was 1.91. The diet constituted 65.1% of rodent prey and the remaining 34.83% of other groups of both vertebrate and invertebrate animals. The mean percentage of prey composition was 31.15% Millardia meltada Soft-furred Field Rat, 12.95% Bandicota bengalensis Lesser Bandicoot Rat, 10.25% Mus booduga Indian Field Mouse, and 10.24% of other rodent species. Of the 34.83% of non-rodent prey, the owls ingested insects (Rhinoceros beetles, 9.58%), Arachnida (Solifugae or Sun spider, Galeodes sp., 9.58%), reptiles (Calotes sp., 3.7%), amphibians (3.56%), shrews (Suncus murinus, 2.84%), and others (5.57%). The Indian Eagle Owls consumed more than one prey per day and chiefly foraged in agricultural crop fields and consumed both small mammals and insects of agricultural importance under crop ecosystems.

New records of Camel Spider Galeodes araneoides Pallas, 1772 (Solifugae, Solpugidae) in the Kherson region (Ukraine)

Information on the records of common Camel Spider, Galeodes araneoides, at archaeological sites (settlements) of the Right Bank of Dnieper territory in the Kherson Region is presented: the species is recorded at one territory (Staroshvedske) based on observations of the authors (confirmed by the photo), and given for other territory (Chervonomaiatske) based on the data of survey. Last time this species was recoded on the territory of continental Ukraine more than 100 years ago.

Smaller Orders of Arachnida in Sudan: A Literature Review

Literature-based species lists for arachnids, excluding spiders and mites, found in the Republic of the Sudan are provided. We summarize records, references, and localities for 17 scorpions (Scorpiones), one harvestman (Opiliones), nine pseudoscorpions (Pseudoscorpiones), 21 camel spiders (Solifugae) and one whip spider (Amblypygi). There are no published records of palpigrades (Palpigradi), whip scorpions (Thelyphonida), schizomids (Schizomida) or ricinuleids (Ricinulei), although at least whip scorpions and ricinuleids would not be expected in East Africa based on their current distribution. Key literature for mites and ticks (Acari) is also mentioned. In general, the Sudanese arachnid fauna has not been documented in detail. Many more species, particularly among the harvestmen and pseudoscorpions, are to be expected, and we offer the data gathered here as a baseline for future work.

Capturing the elusive camel spider (Arachnida: Solifugae): effective methods for attracting and capturing solifuges

Camel spiders (Arachnida: Solifugae) are a notoriously difficult group of arachnids to study. They are almost all strictly nocturnal, fast moving predators that are difficult to find, collect, and rear. In this paper, we present methods for both attracting solifuges in desert field sites and collecting them efficiently using a combination of light attraction and pitfall trapping techniques. Although many of these methods have been used by solifuge collectors for decades, they are not typically described in detail in the literature nor have the methods been consolidated in a single paper. We hope that doing so will enable others to more efficiently target this group of arachnids.

Chelicerates

Compared to other arthropods, such as crustaceans or insects, the term 'chelicerate' often does not evoke a similar sense of recognition or familiarity. Yet the subphylum Chelicerata has been encountered by every living person today, frequently to the effect of fear, awe, or outright revulsion. Chelicerates include such familiar groups as spiders, scorpions, mites, and ticks, as well as an array of bizarre and unfamiliar forms, such as vinegaroons, camel spiders, and hooded tick spiders (Figure 1).

The Arachnology Collection at the Denver Museum of Nature & Science

The Arachnology collection at the Denver Museum of Nature & Science (DMNS) was founded 20 years ago. We describe its inception and early growth from 0 to over 62,000 lots; DMNS volunteers and the key role they play as citizen scientists in the Colorado Spider Survey and collections work such as identification and databasing. We now have more than 40,000 databased and geocoded specimen vials available through Symbiota and GBIF. The collection's research focuses on the biodiversity of the region's spiders, scorpions, cave forms, and solifuge (camel spiders). DMNS is now one of the centers for research on solifuge.

Revision of the camel spider genus Eremocosta Roewer and a description of the female Eremocosta gigas Roewer (Arachnida, Solifugae).

A recent phylogenetic analysis demonstrated that the solifuge genus Eremocosta (Eremobatidae), although not monophyletic, formed a strongly supported group, rendered paraphyletic by the exclusion of E. acuitlapanensis, which we herein determine is misplaced in this genus. We revise the taxonomy of the genus Eremocosta. Nine species of the 13 currently placed in the genus are retained, E. bajaensis (Muma 1986), E. calexicensis (Muma 1951), E. formidabilus (Simon 1879), E. gigas Roewer 1934, E. gigasella (Muma 1970), E. spinipalpis (Kraepelin 1899), E. striata (Putnam 1883), and E. titania (Muma 1951). Eremocosta fusca (Muma 1986) and E. montezuma (Roewer 1934) are returned to the genus Eremorhax along with E. arenarum. Eremocosta hystrix and Eremocosta acuitlapanensis (Vázquez Gaviño-Rojas 2000) are transferred to Eremobates. We re-evaluated E. nigrimana (Pocock 1895) and determined that, since the type shows the ventrodistal concavity (VDC) diagnostic for the genus Eremocosta, it should be retained in that genus; however, because the type locality is identified as Afghanistan, far outside the range of any Eremobatidae, its status and placement remain uncertain. Eremocosta robusta (Roewer 1934) was designated nomen dubium by Muma and we maintain this designation. We provide a key to the species of Eremocosta and provide a description of the female of E. gigas.

Arachnids in Bitterfeld amber: A unique fauna of fossils from the heart of Europe or simply old friends?

Bitterfeld amber, sometimes referred to as Saxon or Saxonian amber, is a potentially significant but poorly known source of arthropod data for the Palaeogene of northern Europe. An important aspect is a long-standing controversy about the age of this amber: namely whether it is equivalent to, and perhaps merely a southerly extension of, the better-known Baltic amber, or whether it is a unique and geological younger deposit sampling a different fauna. Here, we briefly review the Bitterfeld arachnids with particular emphasis on how these data could be used to elucidate the age of this deposit. Five arachnid orders have been recorded from Bitterfeld amber: spiders (Araneae), acariform mites (Acariformes), parasitiform mites (Parasitiformes), harvestmen (Opiliones) and pseudoscorpions (Pseudoscorpiones). This is a lower diversity than Baltic amber, where scorpions (Scorpiones) and camel spiders (Solifugae) have also been recorded. Spiders are the most comprehensively studied group, with more than 75 described species. Other groups such as pseudoscorpions and mites appear to be very diverse, but are virtually undescribed. Morphological overlap is apparent in the arachnid fauna and 40 species are currently shared between Baltic and Bitterfeld amber whilst 50 species are unique to the Bitterfeld deposit. At the family level overlap is even higher, but in all groups Baltic amber appears more diverse than Bitterfeld. This overlap may be interpreted as evidence for temporal conspecifity of the Baltic and Bitterfeld ambers, albeit with the Bitterfeld and Baltic ambers possibly representing independent localities within a larger Eocene European amber area which also included the Rovno amber from the Ukraine. However, caution should be exercised because the taxonomic foundation for such assumptions is far from comprehensive, most of the material remains to be studied in detail using modern techniques of morphological reconstruction. There are further issues with date estimates because some arachnid groups show extraordinary morphological stasis over time, even at species level, which may bias the analyses available. Here, we review the available knowledge on Bitterfeld arachnids and discuss how a detailed assessment of this fauna, and other arthropod taxa, could be generated. Several natural history museums – including Hamburg and Berlin – as well as private collectors host major assemblages of Bitterfeld fossils which may help to clarify the debate about the age and provenance of the material, and the extent to which (morpho)-species were maintained both over geographical distances and potentially geological time.

An annotated type catalogue of the camel spiders (Arachnida: Solifugae) held in the Zoological Museum Hamburg

Solifuges are an enigmatic and poorly studied group of arachnids. Commonly referred to as camel spiders or sun spiders, these animals are voracious predators of small animals and found in arid biomes of the Old World and the Americas. In this paper, we provide a catalogue for the solifuges (Arachnida: Solifugae) that are held at the Center of Natural History in Hamburg. The collections in Hamburg are predominantly historical and were accumulated by Karl Kraepelin between 1889 and 1914 with the help of other famous arachnologists such as Ferdinant Karsch and Eugène Simon. The re-study of these collections indicates that there are 38 type species and 65 type specimens from 10 families. We provide a detailed account of this material, including collection data, taxonomic updates, measurements and high-resolution images for species that are either poorly or not at all illustrated. Most specimens (70%) were collected in Africa as part of colonial expeditions or field surveys but there are also types from Western Asia (11%), and North and South America (19%). We provide an overview of the history of this collection, including a summary of the field surveys during which the specimens were collected and the arachnologists who described the material. Overall, this is the third-largest collection of solifuges in Germany with a distinct biogeographical focus and one of the largest collections of camel spiders in Europe.

First record of Galeodes caspius subfuscus Birula, 1937 (Solifugae, Galeodidae) in Iraq with additional notes on Rhagodixa kurdistanica, Birula 1936 (Solifugae, Rhagodidae)

Abstract: Solifuges were observed in many habitats in Erbil- city/Iraq; on ground, under stones and between grasses especially at night. Two species belong two family Galeodidae and Rhagodidae were identified from the study area, Galeodes caspius subfuscus Birula 1937, recorded for the first time in Iraq. Keywords: solifugids, sun spider, camel – spider, Galeodidae, Rhagodidae

The Second Camel Spider (Arachnida, Solifugae) from Burmese Amber

Summary A second camel spider (Arachnida, Solifugae) from the Late Cretaceous (c. 99 Ma) Burmese amber of Myanmar is described. It is referred to Cushingia cf. ellenbergeri Dunlop et al., 2015. This extinct species is of uncertain familial affinities, but noticeable are similarities to the modern genus Dinorhax Simon, 1879, which is today the only camel spider recorded from Southeast Asia. The present specimen differs from the original holotype in some characters. For example, the number of malleoli strongly suggests that the present specimen is a juvenile, and thus potentially provides valuable data about intraspecific variation within this fossil species.

Morphology of the tracheal system of camel spiders (Chelicerata: Solifugae) based on micro-CT and 3D-reconstruction in exemplar species from three families

We studied the tracheal system of exemplar species representing three families of Solifugae Sundevall, 1833, i.e., Galeodes granti Pocock, 1903, Ammotrechula wasbaueri Muma, 1962 and Eremobates sp., using μCT-imaging and 3D-reconstruction. This is the first comparative study of the tracheal system of Solifugae in 85 years and the first using high-resolution nondestructive methods. The tracheal system was found to be structurally similar in all three species, with broad major tracheae predominantly in the prosoma as well as anastomoses (i.e., connections between tracheal branches from different stigmata) in the prosoma and opisthosoma. Differences among the three species were observed in the presence or absence of cheliceral air sacs, the number of tracheae supplying the heart, and the ramification of major tracheae in the opisthosoma. The structure of the tracheal system with its extensive branches and some anastomoses is assumed to aid rapid and efficient gas exchange in the respiratory tissues of these active predators. The large diameter of cheliceral tracheae (air sacs) of taxa with disproportionally heavier chelicerae suggests a role in weight reduction, enabling solifuges to reach greater speeds during predation. The air sacs may also permit more rapid and efficient gaseous exchange, necessary to operate the musculature of these structures, thereby improving their use for predation in an environment where prey is scarce.

Lateral eye evolution in the arachnids

Summary The distribution of lateral eyes in arachnids and their relatives (Chelicerata) is reviewed, including novel data for selected taxa. Particular focus was given to camel spiders (Solifugae) and whip scorpions (Thelyphonida), for which there are conflicting reports about their eye morphology in the literature, and to the condition in some fossil scorpions (Scorpiones) and some extinct trigonotarbid arachnids (Trigonotarbida), which have lateral eyes with c. 30 or up to 15 individual lenses, respectively. Arachnid outgroups like horseshoe crabs (Xiphosura) and sea scorpions (Eurypterida) have compound lateral eyes, but the hypothesis that reduction of these eyes to five lenses or fewer is a synapomorphy of Arachnida can be rejected. Fossil data indicate, instead, that the arachnid lateral eyes were also originally (semi-) compound, and that reduction to only a handful of lenses must be a homoplastic character state. Note that camel spiders retain vestigial lateral eyes, while fossil ricinuleids had a...

Correction of the Type Locality of Rhagodes Caucasicus Birula, 1905, and the First Record of the Species from Iran With Redescription of the Species from Turkey (Solifugae: Rhagodidae)

ABSTRACT: The type locality of Rhagodes caucasicus Birula, 1905 is corrected and identified as Tuzluca (Kul'p), Igdir Province, eastern Turkey instead of Armenia. A new record for the Iranian solpugid fauna is also reported: Rhagodes caucasicus Birula, 1905 from Zanjan Province, northwestern Iran. The redescription of new material of Rhagodes caucasicus from Turkey is included.