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Guest blog post by Willians Porto and Abel Pérez González
The third-largest group of arachnids, in terms of number of known species, is the harvestmen, with nearly 7,000 described species, ranking just behind spiders and mites. Despite this number, a considerable portion of their diversity is unknown, and many species still remain undescribed.
The harvestmen of the family Triaenonychidae comprise 404 known species and have a peculiar distribution. They are found in temperate regions of the southern hemisphere, with representatives in Australia, New Zealand, South Africa, Madagascar, and southern South America— a typical temperate Gondwana distribution. In the America continent, the diversity is concentrated in the Southern Cone of South America, mainly in the Chilean Valdivian Forest, where 26 species were previously recorded.
In our latest work published in ZooKeys, we present the result of a taxonomic and systematic revision of the South American triaenonychids previously included in the mainly New Zealand genus Nuncia. After examining hundreds of specimens, we redescribed all the four previously known species and described 22 new ones. All these species were included in six genera─one resurrected and five new to science─regarding the genus Nuncia as exclusively to New Zealand. The new systematic arrangement was supported by a comprehensive new phylogenetic analysis based on molecular (UCE + Sanger) data.
The proposed phylogenetic hypothesis reveals the relationships between South American Triaenonychidae and their counterparts from the rest of the world, indicating that the diversity of triaenonychids in the Southern Cone is polyphyletic, reflecting an ancient diversification predating the Gondwana breakup.
Our work represents the most comprehensive contribution to the taxonomy and systematic of South American triaenonychids, almost doubling the number of previously known species. For naming the new taxa, we select names derived from geography, historical figures, and recognized intellectuals. Since most of the newly discovered fauna is distributed across various regions of Chile, the authors decided to honor two prominent figures of Chilean literature. The poet Gabriela Mistral (1889-1957), Nobel laureate in literature in 1945, was honored with the new genus Mistralia, and Pablo Neruda (1904-1973), Nobel laureate in literature in 1971, was honored with the new genus Nerudiella. In addition to tributes to globally renowned Chilean poets, the new species also include dedications to members of the arachnological scientific community and researchers who collaborated on this work.
The taxonomic revision includes hundreds of images that are extremely important for species identification. These images consist of various optical microscopy, stereomicroscopy, and numerous scanning electron microscopy micrographs.
This work is one of the products of years of collaboration between the Arachnology Division of the Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN) and the Giribet Lab in Harvard University and Museum of Comparative Zoology (MCZ). It also represents a continuation of the collaboration initiated in the 20th century by the late Argentinean arachnologist Emilio Maury (MACN) with the Chilean zoologist Tomás Nicolás Cekalovic (Museo de Zoología de la Universidad de Concepción) and the American Museum of Natural History.
Research article:
Porto W, Derkarabetian S, Giribet G, Pérez-González A (2024) Systematic revision of the South American “Nuncia” (Opiliones, Laniatores, Triaenonychidae). ZooKeys 1207: 1-149. https://doi.org/10.3897/zookeys.1207.120068