Next-generation sequencing technologies are rapidly transforming molecular systematic studies of non-model animal taxa. The arachnid order Opiliones (commonly known as “harvestmen”) includes more than 6,400 described species placed into four well-supported lineages (suborders). Fossil plus molecular clock evidence indicates that these lineages were diverging in the late Silurian to mid-Carboniferous, with some fossil harvestmen representing the earliest known land animals. Perhaps because of this ancient divergence, phylogenetic resolution of subordinal interrelationships within Opiliones has been difficult. We present the first phylogenomics analysis for harvestmen, derived from comparative RNA-Seq data for eight species representing all suborders. Over 30 gigabases of original Illumina short-read data were used in de novo assemblies, resulting in 50–80,000 transcripts per taxon. Transcripts were compared to published scorpion and tick genomics data, and a stringent filtering process was used to identify over 350 putatively single-copy, orthologous protein-coding genes shared among taxa. Phylogenetic analyses using various partitioning strategies, data coding schemes, and analytical methods overwhelmingly support the “classical” hypothesis of Opiliones relationships, including the higher-level clades Palpatores and Phalangida. Relaxed molecular clock analyses using multiple alternative fossil calibration strategies corroborate ancient divergences within Opiliones that are possibly deeper than the recorded fossil record indicates. The assembled data matrices, comprising genes that are conserved, highly expressed, and varying in length and phylogenetic informativeness, represent an important resource for future molecular systematic studies of Opiliones and other arachnid groups.

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Pedipalps are the most versatile appendages of arachnids. They can be equipped with spines (Amblypygi), chelae (Scorpiones), or adhesive pads (Solifugae), all of which are modifications to grasp and handle fast-moving prey. Harvestmen (Opiliones) show a high diversity of pedipalpal morphologies. Some are obviously related to prey capture, like the enlargement and heavy spination of Laniatores pedipalps. Many Dyspnoi, by contrast, exhibit thin, thread-like pedipalps that are covered with complex glandular setae (clavate setae). These extrude viscoelastic glue that is used to immobilize prey items. Comparable setae (plumose setae) have previously been found in representatives of both Eupnoi and Dyspnoi, yet comprehensive data on their distribution are lacking. This study examined the distribution and ultrastructure of glandular setae in harvestmen and related them to pedipalpal morphology. Pedipalpal and setal characters were analysed in a phylogenetic framework. We found that glandular setae are synapomorphic for and widespread in the Palpatores clade (Eupnoi plus Dyspnoi). Their occurrence correlates with pedipalp morphology and feeding habit. Remnants of arthropod cuticular structures or secretions, frequently found attached to glandular setae, and behavioural observations, underlined the importance of the setae for capturing and securing prey. We hypothesize that glandular setae evolved as an adaptation to capture small and agile prey, which are hard to catch with a capture basket. Details of ultrastructure indicate that the setae are derived sensilla chaetica, with both a secretory and sensory function. Derived ultrastructural characters of the glandular setae, such as slit-like channel openings and a globular arrangement of the microtrichia, may increase their effectiveness. The functional role of further pedipalpal modifications, such as apophyses, stalked and hyperbendable joints, and curved segments, as well as sexual dimorphism and ontogenetic polymorphism, are discussed. Some implications of the results obtained for the taxonomic treatment of Phalangiidae are also discussed. These results shed new light on the biology and evolutionary history of this fascinating group of arthropods.

An update of the systematics and determination key of the Opiliones suborder Dyspnoi is provided. The included catalogue represents the first comprehensive species and synonymy listing since Roewer (1923). It summarises all taxonomic changes to date and attempts to be a sound basis against the exponential growing number of online errors, for which examples are given. Species taxonomy features most obvious changes within the Nemastomatidae. The number of species in the collective genus Nemastoma is reduced from 96 (Hallan 2005) to its sensu stricto definition of 7, and the excluded names are transferred to other genera or considered as nomina dubia, predominantly in Paranemastoma. The systematics of the superfamily Ischyropsalidoidea is discussed and family-level diagnoses are renewed to support taxonomical changes: The morphological heterogeneity in the Sabaconidae is resolved by reverting the family to its original monogeneric state. Taracus and Hesperonemastoma are separated as Taracidae fam. n., and Crosbycus is tentatively transferred to this assembly. The remaining genera of Ceratolasmatidae, Acuclavella and Ceratolasma, are included as subfamily Ceratolasmatinae in the Ischyropsalididae and Ischyropsalis is assigned subfamily status, respectively. Other nomenclatural acts are restricted to species-group level with the following synonymies established: Sabacon jonesi Goodnight & Goodnight, 1942 syn. n. (=cavicolens (Packard, 1884)), Dicranolasma diomedeum Kulczyński, 1907 syn. n. (=hirtum Loman, 1894), Mitostoma (Mitostoma) sketi Hadži, 1973a syn. n. (=chrysomelas (Hermann, 1804)), Mitostoma asturicum Roewer, 1951 syn. n. (=pyrenaeum (Simon, 1879a)), Nemastoma formosum Roewer, 1951 syn. n. (=Nemastomella bacillifera bacillifera (Simon, 1879a)), Nemastoma reimoseri Roewer, 1951 syn. n. (=Paranemastoma bicuspidatum (C.L. Koch, 1835)), Nemastoma tunetanum Roewer, 1951 syn. n. (=Paranemastoma bureschi (Roewer, 1926)), Phalangium flavimanum C.L. Koch, 1835 syn. n. (=Paranemastoma quadripunctatum (Perty, 1833)), Crosbycus graecus Giltay, 1932 syn. n. (=Paranemastoma simplex (Giltay, 1932)), Nemastoma bimaculosum Roewer 1951 syn. n. (=Paranemastoma titaniacum (Roewer, 1914)), Trogulocratus tunetanus Roewer, 1950 syn. n. (=Calathocratus africanus (Lucas, 1849)), Trogulus albicerus Sø-rensen, 1873 syn. n. (=Calathocratus sinuosus (Sørensen, 1873)), Metopoctea exarata Simon, 1879a syn. n. (=Trogulus aquaticus Simon, 1879a), Trogulus galasensis Avram, 1971 syn. n. (=Trogulus nepaeformis (Scopoli, 1763)) and Trogulus roeweri Avram, 1971 syn. n. (=Trogulus nepaeformis (Scopoli, 1763)). Paranemastoma werneri (Kulczyński, 1903) is elevated from subspecies to species. Ischyropsalis luteipes Simon, 1872b is proposed as nomen protectum, taking precedence over Lhermia spinipes Lucas 1866 nomen oblitum. The same accounts for Anelasmocephalus cambridgei (Westwood, 1874) nomen protectum, taking precedence over Trogulus violaceus Gervais, 1844 nomen oblitum, Trogulus closanicus Avram, 1971 nomen protectum over Trogulus asperatus C...

Within the well researched European fauna of harvestmen, the genus Trogulus Latreille exhibits unexpectedly high cryptic diversity. The species’ uniform morphology hinders an exclusively morphological approach to their systematics and taxonomy, and a preliminary molecular study estimated the number of species to be three times higher than currently known. The current study focuses on a clearly defined species-group within Trogulus, combining molecular (~1700 bp 28S rRNA and the cytochrome b gene), distributional, morphometric and morphological data. Relationships are reconstructed using Bayesian inference, maximum parsimony and maximum likelihood and this information is subsequently used to evaluate morphological characters for systematic usability and to identify biogeographical processes leading to speciation events. The Trogulus coriziformis species-group is defined and diagnosed and includes eight species. Three species are redefined: T. coriziformis C. L. Koch, 1839, for which a neotype is designated, and T. aquaticus Simon, 1879 and T. cristatus Simon, 1879 for which lectotypes are designated. Four species are described as new: T. balearicus, sp. nov. from the Balearic Islands, T. huberi, sp. nov. from southern Portugal, T. prietoi, sp. nov. from Andalusia, Spain, and T. pyrenaicus, sp. nov. from the central Pyrenees. Trogulus lusitanicus Giltay, 1931 is used as collective name and probably refers to a composite of species presently difficult to tell apart. Trogulus salfii De Lerma, 1948 is proposed as a synonym for T. coriziformis. Within Trogulus, the molecular genetic data support monophyly and basal placement of the Trogulus coriziformis species-group. The species to differ in external morphology (size, papillation of palps, apophyses of legs, pattern of body papillation, morphometric data), 28S and cytochrome b autapomorphies and to a lesser degree by male genital morphology. The species-group is confined to the western Mediterranean area and its species are allopatrically distributed. Their present distribution corresponds to geological processes in the Miocene and Pliocene indicating that this group of organisms may be of considerable value for further biogeographic studies.