The newest and the oldest species in the same vial: Description of a new species of Ceratomontia Roewer, 1915 and redescription of Ceratomontia capensis Roewer, 1915 (Opiliones: Laniatores: Triaenonychidae).

Ceratomontia starengai sp. nov. is described from South Africa, based on one specimen found in the type series of Ceratomontia capensis Roewer, 1915, which is redescribed in this work. The presence of this new species represents sympatry of Ceratomontia species, something not uncommon for species of the family Triaenonychidae. Images of the genital morphology, which are crucial to the diagnosis of the group, are included in the descriptions.

Recent speciation and phenotypic plasticity within a parthenogenetic lineage of levantine whip spiders (Chelicerata: Amblypygi: Charinidae).

Caves constitute ideal study systems for investigating adaptation and speciation, as the abiotic conditions shared by aphotic habitats exert a set of environmental filters on their communities. Arachnids constitute an important component of many cave ecosystems worldwide. We investigated the population genomics of two whip spider species: Sarax ioanniticus, a widely distributed parthenogenetic species found across the eastern Mediterranean; and S. israelensis, a recently described troglomorphic species that is endemic to caves in Israel. Here, we show that S. israelensis is completely genetically distinct from S. ioanniticus and most likely also a parthenogen. Counterintuitively, despite the lack of genetic variability within S. ioanniticus and S. israelensis, we discovered considerable variation in the degree of median eye reduction, particularly in the latter species. Natural history data from captive-bred specimens of S. israelensis validated the interpretation of parthenogenesis. Our results are most consistent with a scenario of a sexual ancestral species that underwent speciation, followed by independent transitions to apomictic parthenogenesis in each of the two daughter species. Moreover, the lack of genetic variability suggests that variation in eye morphology in S. israelensis is driven exclusively by epigenetic mechanisms.

Evidence of positive selection on six spider developmental genes.

Spiders constitute more than 49,000 described species distributed all over the world, and all ecological environments. Their order, Araneae, is defined by a set of characteristics with no parallel among their arachnid counterparts (e.g., spinnerets, silk glands, chelicerae that inoculate venom, among others). Changes in developmental pathways often underlie the evolution of morphological synapomorphies, and as such spiders are a promising model to study the role of developmental genes in the origin of evolutionary novelties. With that in mind, we investigated changes in the evolutionary regime of a set of six developmental genes, using spiders as our model. The genes were mainly chosen for their roles in spinneret ontogeny, yet they are pleiotropic, and it is likely that the origins of other unique morphological phenotypes are also linked to changes in their sequences. Our results indicate no great differences in the selective pressures on those genes when comparing spiders to other arachnids, but a few site-specific positive selection evidence were found in the Araneae lineage. These findings lead us to new insights on spider evolution that are to be further tested.

Three new species of Cosmetidae C.L. Koch, 1839 from South America (Opiliones: Cosmetidae).

Three new species of harvestmen are described based on morphology. Taito mayoruna spec. nov. from Jenaro Herrera province, Loreto, Peru is differentiated from other species of Taito Kury Barros, 2014 by features such as anal operculum armed, and femur IV with two retro-distal spines. Taito curupira spec. nov. from Porto Velho, Rondonia, Brazil is recognized by an H-shaped color pattern, femur IV curved dorsally and armed with medial prolateral and retrolateral tubercles. A third species herein described, Eulibitia chacuamarei spec. nov., from Trinidad, Casanare, Colombia is distinguished by the absence of a ladder mask and by the presence of blunt tubercles on areas I, III and the posterior margin. Penial morphology is described, and SEM micrographs are included.

On Spinopilar from Rio de Janeiro state with description of three new species (Opiliones, Laniatores, Cryptogeobiidae).

The genus Spinopilar Mello-Leitão, 1940 currently has seven species distributed in eastern Brazil, Argentina and Paraguay. Three species are hitherto known from Rio de Janeiro state (RJ), in the Brazilian Atlantic Forest. In this paper, five species from Rio de Janeiro state (RJ) are studied as follows: (1) Spinopilar armatus Mello-Leitão, 1940, the type species of Spinopilar, originally described without illustrations, is herein redescribed based on additional material from the metropolitan area of Rio de Janeiro city. (2) Spinopilar anomalis (Sørensen, 1932) is a species never recorded again after the original description. A new diagnosis is provided for S. anomalis based on a translation of the original Latin description. (3) Spinopilar jocheni spec. nov. is described from Barra de Guaratiba, Southeast RJ. It is characterized by the unarmed mesotergal areas. (4) Spinopilar martialis spec. nov. is described from Macaé, northern RJ. It is characterized by the pars stridens of the stridulatory organ on the pedipalpal femur, the unusual armature of scutal areas (2-2-10-10) and the extremely complex lobes of the stigmatic area in males, which connect the apophyses of coxa and trochanter IV. (5) Spinopilar magistralis spec. nov. is described from Búzios. It is characterized by extreme stoutness of leg IV and an elevated campaniform ocularium. A key is provided to 9 of the 10 species of Spinopilar and a new diagnosis is given for the genus. Two novel structures so far known only in Spinopilar are described: (1) a third type of pars stridens, which is different from the Tibangara-type and the Bissulla/Pseudopachylus-type both in topology and in structure of the ridges; (2) a proximal primary trochanteral cluster (PTC) composed of modified setae situated on the main apophysis of trochanter IV of males.

A new cavernicolous harvestman, Texella martensi n. sp., from the Mojave Desert, California (Opiliones: Laniatores: Phalangodidae).

A new species of Texella, T. martensi n. sp., is described on the basis of a single male specimen from Titus Canyon Cave, Inyo County, California. The species belongs to the kokoweef group in having a spur on trochanter IV and lacking a postopercular process on the abdomen. Texella martensi n. sp. is the most troglomorphic of the four species of Texella now recorded from the Mojave Desert and it is the northernmost member of the group.

Martensopsalis, a new genus of Neopilionidae from New Caledonia (Opiliones: Eupnoi).

New Caledonia has an endemic opiliofauna with two named species of Triaenonychidae, 17 Troglosironidae and eight Zalmoxidae. The recent finding of Neopilionidae on Grande Terre was thus surprising, and required the formal description of a new genus, which we undertake here. Martensopsalis gen. nov. is characterized by a small unsclerotized body with a unique palp with a pointed basal apophysis on the ventral side of the femur and with a distal apophysis on the prolateral side of the patella. The distinct external morphology, simple penis and unique phylogenetic position justify the erection of the new genus with Martensopsalis dogny spec. nov. as its type species. In addition to the type locality we report several other localities of putative congeneric, yet undescribed species.

First record of Travunioidea (Arachnida: Opiliones: Laniatores) from China, with the description of a new monotypic genus from a cave.

A new genus and species of troglobitic Opiliones, Sinonychia martensi gen. n. sp. n., is described and illustrated. This is the first report of the superfamily Travunioidea Absolon Kratochvíl, 1932 from China. The new species is assigned to Cladonychiidae Hadzi, 1935 on the basis of morphology of midgut and male genitalia, and can be easily distinguished from related genera by several characters.

A new species of the solifuge genus Galeodes Olivier, 1791 from southeastern Turkey (Solifugae, Galeodidae).

The family Galeodidae Sundevall, 1833 is the most speciose family of order Solifugae. A new galeodid, Galeodes hakkariensis sp. n., is described and illustrated on the basis of both sexes from Hakkari Province in Turkey. The flagellum, flagellar complex setae, setal arrangements on the tarsi and metatarsi of pedipalps and walking legs, shape and number of the stridulatory setae, dentition, and the other characteristics are described and illustrated in details. With this description, the number of known species of Galeodes Olivier, 1791 is raised to 174.

New and interesting palpigrades (Arachnida, Palpigradi) of the genera Koeneniodes Silvestri, 1913 and Prokoenenia Börner, 1901 from Asia.

Two new species of palpigrades are described: a soil-dwelling species of the genus Koeneniodes Silvestri, 1913 from a broadleaf forest in Tibet and an extraordinary cave-dwelling species from Jinhua cave in China belonging to Prokoenenia Börner, 1901. Koeneniodes tibetanus sp. n. is related to Koeneniodes spiniger from Thailand. The two species share the presence of four thick and spiniform setae on the second lobe of the female genitalia; they differ in the number of thick setae on opisthosomal sternite IV, the number of cheliceral teeth, the coxal setal formula, and the morphology of the spiniform setae. Prokoenenia sarcodactylica sp. n. is based on an immature female from Jinhua Cave, Beijing. The presence of 18 finger-shaped blades in the lateral organs-unique among palpigrades , the large body size (2150 µm) and the extremely long basitarsus IV (205 µm) indicate that the new species is the first undoubtedly caveadapted Prokoenenia. This is also the first record of the genus Prokoenenia from China.

Outsourcing a visual neuropil - The central visual system of the median eyes of Galeodes granti Pocock, 1903 (Arachnida: Solifugae).

Only a few studies have examined the central visual system of Solifugae until now. To get new insights suitable for phylogenetic analysis we studied the R-cell (or retinula cell) projections and visual neuropils of Galeodes granti using various methods. G. granti possesses large median eyes and rudimentary lateral eyes. In this study, only the R-cells and neuropils of the median eyes were successfully stained. The R-cells terminate in two distinct visual neuropils. The first neuropil is located externally to the protocerebrum directly below the retina, the second neuropil lies in the cell body rind of the protocerebrum, and immediately adjacent is the arcuate body. This layout of the median eye visual system differs from Arachnopulmonata (Scorpiones + Tetrapulmonata). However, there are several similarities with Opiliones. In both, (1) the R-cells are connected to a first and second visual neuropil and not to any other region of the brain, (2) the first neuropil is not embedded in the cell body rind of the protocerebrum, it is rather external to the protocerebrum, (3) the second visual neuropil is embedded in the cell body rind, and (4) the second neuropil abuts the arcuate body. These findings may provide important new characters for the discussion on arachnid phylogeny.

Evolutionary and functional substitution of extrinsic musculature in Solifugae (Arachnida).

The locomotory system of Solifugae is distinct from that of other Arachnida in several ways. Only three pairs of legs are involved in locomotion, while the first pair function as sensory appendages. Morphologically, the proximal region of the locomotory system in Solifugae is characterized by fused coxae. Within the prosoma of Solifugae, an endosternite is missing: in other Arachnida, this endosternite serves as the proximal attachment site for a portion of the extrinsic musculature. How then do these skeletal modifications influence the muscular anatomy in the proximal region of the locomotory system? To answer this question, we studied the skeletomuscular anatomy of Galeodes granti at the interface between the prosoma and legs, reinvestigating the complex muscular anatomy of this body region for the first time in over 80 years and-for the first time-using detailed micro-computed tomography scans to analyze the skeletomuscular morphology. Specimens of three further species were checked for comparison. The analysis revealed differences in the number and composition of coxa-trochanter muscles in each of the four pairs of legs. These are compared in the light of serial homology. The comparison between the proximal locomotory system of Solifugae and that of other Arachnida unveils a series of analogies. Primarily, the coxa-trochanter joint is the most proximal joint to move the leg relative to the prosoma. Therefore, we argue that from a morpho-functional point of view, the coxa-trochanter muscles in Solifugae should be considered secondary extrinsic musculature. Thus, the legs gain a stable, articulated joint in the most proximal region of the leg to the prosoma, which might be advantageous for agile locomotion.

Arachnid monophyly: Morphological, palaeontological and molecular support for a single terrestrialization within Chelicerata.

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.

Adaptations for matrotrophy in the female reproductive system in the pseudoscorpion Chelifer cancroides (Chelicerata: Pseudoscorpiones, Cheliferidae).

Pseudoscorpiones (pseudoscorpions, false scorpions) is an order of small terrestrial chelicerates. While most chelicerates are lecithotrophic, that is, embryos develop due to nutrients (mostly yolk) deposited in the oocyte cytoplasm, pseudoscorpions are matrotrophic, that is, embryos are nourished by the female. Pseudoscorpion oocytes contain only a small amount of yolk. The embryos develop within a brood sac carried on the abdominal site of the female and absorb nutrients by a pumping organ. It is believed that in pseudoscorpions nutrients for developing embryos are produced in the ovary during a postovulatory (secretory) phase of the ovarian cycle. The goal of our study was to analyze the structure of the female reproductive system during the secretory phase in the pseudoscorpion Chelifer cancroides, a representative of the family Cheliferidae, considered to be one of the most advanced pseudoscorpion taxa. We use diverse microscopic techniques to document that the nutritive fluid is produced not only in the ovaries but also by the epithelial cells in the oviducts. The secretory active epithelial cells are hypertrophic and polyploid and release their content by fragmentation of apical parts. Our observations also indicate that fertilization occurs in the oviducts. Moreover, in contrast to previous findings, we show that secretion of the nutritive material starts when the fertilized oocytes reach the brood sac and thus precedes formation of the pumping organ. Summing up, we show that C. cancroides exhibits traits of advanced adaptations for matrotrophy due to coordinated secretion of the nutritive fluid by the ovarian and oviductal epithelial cells, which substantially increases the efficiency of nutritive fluid formation. Since the secretion of nutrients starts before formation of the pumping organ, we suggest that the embryos are able to absorb the nutritive fluid also in the early embryonic stages.

A relictual troglomorphic harvestman discovered in a volcanic cave of western Argentina: Otilioleptes marcelae, new genus, new species, and Otilioleptidae, new family (Arachnida, Opiliones, Gonyleptoidea).

The troglomorphic harvestman Otilioleptes marcelae gen. nov., sp. nov. from the basaltic cave Doña Otilia, Payunia region, Mendoza Province, Argentina, is described. Its systematic affinities were studied through cladistic and Bayesian analyses that included representatives of Gonyleptoidea; it was determined to represent a new monotypic family, Otilioleptidae fam. nov., occupying a basal position within the clade Laminata. This species shows accentuated troglomorphic traits, typical for troglobitic harvestmen: elongated appendages, depigmentation, reduction of eyes and fading of scutal sulci. Additionally, it almost lacks sexual dimorphism, the distal portion of coxa IV is not completely fused to the stigmatic segment, and penis morphology is remarkably divergent with other Laminata; these features cannot be attributed to cave adaptation and may reflect early lineage divergence. Otilioleptes marcelae is the first troglobitic gonyleptoid known from a lava tube. The xeric environments around the cave (Patagonian ecoregion) and the paleoenvironmental history of the area suggest the relictual character of O. marcelae. Scattered evidence supports a long time evolutionary scenario and a presumable relationship with the Chilean opiliofauna (especially with genus Osornogyndes). A comparative overview of all known troglobitic gonyleptoids is provided. The urgent need to protect this new species and its unique cave environment is emphasized.

Morphology of Ovaries and Oogenesis in Chelicerates.

The subphylum Chelicerata represents one of the oldest groups among arthropods and comprises more than a dozen orders. Representatives of particular orders differ significantly in their external morphology, reproductive biology, behavior, and structure of internal organs, e.g. of the respiratory system. However, in almost all chelicerates (excluding some mites) the female gonads show a similar architecture. In this chapter, the chelicerate-type ovary structure and the course of oogenesis are described. Structural and functional diversities of the chelicerate-type ovary in non-matrotrophic and matrotrophic arachnids are also presented.

The visual system of Thelyphonida (whip scorpions): Support for Arachnopulmonata.

Only a few studies have examined the central visual system of Thelyphonida (whip scorpions) until now. To obtain new insights suitable for phylogenetic analysis we studied the axonal trajectories and neuropil architecture of the central visual systems of two whip scorpion species (Mastigoproctus giganteus and Typopeltis dalyi) with different neuroanatomical techniques (Cobalt fills, Wigglesworth stains, and µCT). The central visual system of whip scorpion comprises one pair of median eyes and one pair of lateral eye triplets. The R-cells (or retinula cells) of both eye types each terminate in a first and a second visual neuropil. Furthermore, a few R-cell fibres from the median eyes leave the second median eye visual neuropil and terminate in the second and the first lateral eye neuropil. This means R-cell terminals from the lateral eyes and the median eyes overlap here. Additionally, the arcuate body and mushroom bodies are described. A detailed comparison of our findings with previously studied chelicerate central visual systems seems to support a monophyly of Arachnopulmonata, i.e. a clade comprising Tetrapulmonata (Thelyphonida, Schizomida, Amblypygi, and Araneae) and Scorpions. Furthermore, the architecture of the central visual systems hints at a close evolutionary relationship of Arachnopulmonata and Xiphosura.

Description of a new species of Surazomus (Arachnida: Schizomida), with comments on homology of male flagellum and mating march anchorage in the genus.

Surazomus saturninoae sp. nov. is described from eastern Amazon. The male has a pentagonal flagellum, similar to those of three other species in the genus. These four species are herein gathered as the arboreus-group of Surazomus. We present a brief synopsis of chaetotaxy description in hubbardiines and several homology proposals for the flagellum of the species in the arboreus-group: the posterior lobes may be homologous to the lateral lobes of hubbardiine species with trilobed flagella; the setal brush with 4-5 setae on the posterior lobe may be composed of one Dl2 seta and enlarged lobular microsetae; the single, median posterior coupling pocket may be homologous to the pair of posterior pockets seen in other hubbardiines; the single, median anterior coupling pocket may be homologous to the pair of pockets on the anterior border of the flagellum seen in other hubbardiines. Based on the morphology of these pockets and the chelicerae within Surazomus, we discuss the anchoring mechanism during the mating march.

Miniaturisation in Chelicerata.

Arachnids and their relatives (Chelicerata) range in body length from tens of centimetres in horseshoe crabs down to little more than 80-200 µm in several groups of mites. Spiders (Araneae) show the widest range within a given Bauplan - the largest species being ca. 270 times longer than the smallest - making them excellent models to investigate scaling effects. The two mite clades (Parasitiformes and Acariformes) are the main specialists in being small. Miniaturisation, and its consequences, is reviewed for both fossil and extant chelicerates. Morphological changes potentially related to miniaturisation, or adapting to the ecological niches that small size allows, include reduction in the length and number of legs, loss of prosomal arteries (and eventually also the heart), replacement of book lungs by tracheae, or even loss of all respiratory organs. There may also be evolutionary novelties, such as the acquisition of structures by which some mites attach themselves to larger hosts. The observed character distributions suggest a fairly fundamental division between larger pulmonate (lung-bearing) arachnids and smaller, non-pulmonate, groups which could reflect a phylogenetic dichotomy. However, it is worth noting that lineages of tiny spiders were originally fully pulmonate, but have acquired some typically non-pulmonate features, while camel spiders (Soli-fugae) can be large but have a Bauplan suggestive of smaller, non-pulmonate, ancestors.

The sensory equipment of a sandokanid: An extreme case of tarsal reduction in harvestmen (Arachnida, Opiliones, Laniatores).

The study of sensory structures has the potential to provide insights into the natural history and evolution of animals. The sensory structures of arachnids are usually concentrated on the pedipalps (the tritocerebral appendages) or on the distal podomere (tarsus) of the anterior walking legs, the latter being the case for armored harvestmen (Opiliones, Laniatores). Therefore, modifications of the tarsus could have direct impacts on the sensory equipment of these animals. Using scanning electron microscopy, we investigated the sensory equipment in an extreme case of reduction in tarsal articles in the harvestman Sandokan truncatus (Sandokanidae), which bears a single tarsomere in all legs, and the potential consequences of this reduction. Additionally, we review the literature on the natural history of the family Sandokanidae. Tarsomeres of all legs are equipped with gustatory sensilla, mechanoreceptors, and a pore organ, but wall-pored olfactory sensilla are restricted to tarsi I and II. Tarsi II present a higher density of olfactory sensilla and also putative campaniform sensilla (strain detectors), which indicates a special sensory function of this pair of legs. Other podomeres are covered with shelled sensilla, a probable chemoreceptor previously unreported in Opiliones. Overall, S. truncatus has types of sensilla largely comparable to harvestmen with longer and subdivided tarsi. However, S. truncatus also exhibits extra-tarsal sensory fields of sensilla basiconica (putative thermo-/hygroreceptors) in previously undescribed sites, and the unique pore organs. Our results establish a basis for further research investigating the natural history, as well as the evolutionary correlations and mechanistic causes of the tarsal reduction in this enigmatic lineage.