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

Abstract

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.

Glacial refugia, recolonization patterns and diversification forces in Alpine‐endemic Megabunus harvestmen

“…The final data set, taken from Wachter et al . (), included 435 individuals from 75 localities (Table S1, Supporting information), with mtDNA available for all individuals and an average of 6.76% missing data in the nuclear loci (Table S1, Supporting information).…”

“…Eight of eleven known Megabunus species have restricted distributions in the European Alps where they live on rocks and almost vertical cliffs in shaded exposition, mainly in high altitudes (Martens ; Chemini ; Wachter et al . ). Megabunus species belong to the low‐vagility harvestmen, but dispersal abilities vary among species.…”

“…; Wachter et al . ). In accordance with the general tendency of asexuals to occur in marginal, disturbed and spatially structured habitats (Cuellar ; Peck et al .…”

“…Species boundaries in the narrow endemic species of the M. bergomas and rhinoceros complexes have been reconsidered by Wachter et al . () using integrative taxonomy (Schlick‐Steiner et al . ), which resulted in the detection of three cryptic species ( cryptobergomas, coelodonta and lentipes ).…”

The relationship between epicuticular long-chained hydrocarbons and surface area - volume ratios in insects (Diptera, Hymenoptera, Lepidoptera)

“…Hence, CHCs are effected by selection arising from both functions [10]. Furthermore, hydrocarbons are also present on the cuticle of several other terrestrial arthropods, presumably having similar functions in communication and waterproofing [11, 12]. The function of CHCs as a protective barrier against water loss has been hypothesized, but only partly experimentally proven [2, 13–15].…”