Taking the discovery approach in integrative taxonomy: decrypting a complex of narrow-endemic Alpine harvestmen (Opiliones: Phalangiidae: Megabunus)

Species delimitation is fundamental for biological studies, yet precise delimitation is not an easy task, and every involved approach has an inherent failure rate. Integrative taxonomy, a method that merges multiple lines of evidence, can profoundly contribute to reliable alpha-taxonomy and shed light on the processes behind speciation. In this study, we explored and validated species limits in a group of closely related Megabunus harvestmen (Eupnoi, Phalangiidae) endemic to the European Alps. Without a priori species hypotheses, we used multiple sources of inference, including mitochondrial and multilocus nuclear DNA, morphometrics and chemistry. The results of these discovery approaches revealed morphological crypsis and multiple new species within two of the five hitherto known species. Based on our analyses, we discussed the most plausible evolutionary scenarios, invoked the most reasonable species hypotheses and validated the new species limits. Building upon the achieved rigour, three new species, Megabunus cryptobergomas Muster and Wachter sp. nov., Megabunus coelodonta Muster and Steiner sp. nov., and Megabunus lentipes Muster and Komposch sp. nov., are formally described. In addition, we provide a dichotomous morphological key to the Megabunus species of the Alps. Our work demonstrates the suitability of integrative, discovery-based approaches in combination with validation approaches to precisely characterize species and enabled us to implement nomenclatural consequences for this genus.

Three new species in the harvestmen genus Acuclavella (Opiliones, Dyspnoi, Ischyropsalidoidea), including description of male Acuclavella quattuor Shear, 1986

In Shear's (1986) cladistic analysis of the Ischyropsalidoidea, he described the new genus Acuclavella including four new species from the Pacific Northwest states of Washington and Idaho. Several of these species descriptions were based on very limited sample sizes. Our recent field work has increased by more than an order of magnitude both the number of specimens and known localities for Acuclavella. We use this new material to interpret species limits in Acuclavella using morphometric analyses and DNA sequence data from four gene regions. We sequence for the first time the protein-coding homolog of the Wnt2 gene for phylogenetic reconstruction in Opiliones. Our multi-locus phylogeny corroborates a sister relationship between Acuclavella and Ceratolasma, as hypothesized using morphology by Shear (1986). Within Acuclavella, morphometric clusters and reciprocal allelic monophyly allows recognition of three additional species: Acuclavella leonardi sp. n., Acuclavella sheari sp. n., and Acuclavella makah sp. n. This work also describes the previously unknown male of Acuclavella quattuor, from specimens collected at the type locality. Our research identifies a number of novel morphologies for Acuclavella, including females with four pairs of spines, individuals with three pairs of spines on scute areas I-III, and a population with two pairs of spines disjunct from Acuclavella quattuor, which was diagnosed with this spination character. We were unable to assign these populations to existing species, and conservatively do not yet recognize them as new. Intrageneric morphometrics and phylogenetic inference in Acuclavella were often concordant. However, we demonstrate that species delimitation signal would not be detected if only a single line of evidence were utilized.

The evolutionary and biogeographic history of the armoured harvestmen – Laniatores phylogeny based on ten molecular markers, with the description of two new families of Opiliones (Arachnida)

We investigated the internal phylogeny of Laniatores, the most diverse suborder of Opiliones, using sequence data from 10 molecular loci: 12S rRNA, 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I (COI), cytochrome b, elongation factor-1α, histones H3 and H4, and U2 snRNA. Exemplars of all previously described families of Laniatores were included, in addition to two families – Petrobunidae, fam. nov. and Tithaeidae, fam. nov. – that we erect herein. Data analyses were based on maximum likelihood and Bayesian approaches on static alignments, and included phylogenetic tree estimation, molecular dating, and biogeographic analysis of ancestral area reconstruction. The results obtained include the monophyly of Laniatores and the infraorder Grassatores – the focus of this study – as well as support for numerous interfamilial relationships. The two new families described cluster with other South-east Asian families (Podoctidae and Epedanidae). Diversification of Laniatores is estimated at ~348 Mya, and origin of most Grassatores superfamilies occurs in a ~25 million year span of time immediately after the end-Permian mass extinction (254 Mya). Ancestral range reconstruction of the clade (Samooidea + Zalmoxoidea) suggests that the ancestral range of Samooidea comprises West Tropical Gondwana (West Africa + Neotropics), whereas that of Zalmoxoidea is exclusively Neotropical. The following additional taxonomic changes are proposed: (1) Remyus is transferred to Phalangodidae, and (2) Escadabiidae and Kimulidae are transferred to Zalmoxoidea.