Redescription of Promecostethus unifalculatus, the only known harvestman from Crozet Islands (Opiliones: Triaenonychidae)

• Published in: Zootaxa
• Main Authors: PORTO, WILLIANS, PÉREZ-GONZÁLEZ, ABEL
• Format: Article in Journal/Newspaper
• Language: English
• Published: Mangolia Press 2020
• Subjects: Opiliones; Crozet Islands; Insidiatores; Laniatores; Nuncia; Taxonomy
• Online Access: https://www.mapress.com/j/zt/article/view/zootaxa.4861.1.8; https://doi.org/10.11646/zootaxa.4861.1.8

Promecostethus unifalculatus Enderlein, 1909, is the only representative of the order Opiliones from the Crozet Islands. The species belongs to the family Triaenonychidae and is biogeographically interesting because it is a candidate for transoceanic dispersal, a very rare event in this ancient family. Despite this significance, P. unifalculatus is taxonomically still poorly known, and a redescription of this species using modern taxonomic standards is urgently needed. Here we redescribe the species, offer the first description and illustrations of the male genitalia and provide a full exomorphological survey of the species using scanning electron microscopy. Furthermore, we provide an emended diagnosis for the genus Promecostethus and discuss its relationship with some morphologically similar genera.