Phylogenetic Analysis and Taxonomy of Opiliones

Opiliones, commonly known as harvestmen, represent a highly diverse order of arachnids with more than 6 500 described species distributed across four suborders. Phylogenetic studies over the past decades have integrated morphological characters and molecular markers to resolve relationships at family, genus and species levels. These analyses have revealed deep divergences between the major clades—Cyphophthalmi, Eupnoi, Dyspnoi and Laniatores—reflecting ancient Gondwanan and Laurasian biogeographic events. Morphological traits of the dorsal scutum, cheliceral armature and male genitalia remain key to delimiting taxa, but have been increasingly supplemented by ribosomal and mitochondrial DNA sequences analysed under maximum likelihood and Bayesian frameworks. Total-evidence approaches that combine molecular and anatomical data are clarifying the timing of lineage diversification and the evolution of troglomorphic adaptations in cave-dwelling taxa. Taxonomic revisions prompted by these phylogenies have led to the description of new genera and families, the redefinition of subfamilies and the synonimisation of taxa that do not form natural monophyletic groups. Advances in bioinformatics and of high-throughput sequencing now promise more comprehensive genomic sampling, offering a path towards a stable, global classification of Opiliones and new insights into their evolutionary history and ecological roles in terrestrial and subterranean ecosystems.

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Phylogenetic Analysis and Taxonomy of Opiliones publication trend

The graph below shows the total number of articles in phylogenetic analysis and taxonomy of opiliones across all publications each year (not limited to Nature Index journals).

Technical terms

Cladistic analysis: A method of inferring evolutionary relationships by coding shared derived morphological or molecular characters into a data matrix and identifying the most parsimonious tree(s).

Maximum likelihood: A statistical framework for phylogenetic inference that identifies the tree topology most likely to have produced the observed sequence data under a specified evolutionary model.

Bayesian inference: A probabilistic approach to phylogeny reconstruction that estimates posterior probabilities of tree topologies and model parameters by integrating prior information with likelihoods.

Monophyly: The condition of a taxonomic group consisting of an ancestor and all of its descendants, which is a requirement for natural classification.

References

1. Phylogenetic relationships of the genus Mischonyx Bertkau, 1880, with taxonomic changes and three new species description (Opiliones: Gonyleptidae). PeerJ (2021).
2. Revision of the southern Andean genus Sadocus Sørensen, 1886 (Opiliones, Gonyleptidae, Pachylinae). ZooKeys (2021).
3. The short-legged Andean cosmetids revisited: the genus Libitia Simon, 1879 with description of two new species (Opiliones, Cosmetidae). European Journal of Taxonomy (2020).