A spiny problem: iterative taxonomic review and species delimitation in the Micrathena triangularispinosa species group (Araneae: Araneidae)

MARTINS, PEDRO H; IVAN L. F. MAGALHAES; TEOFÂNIA H D A VIDIGAL; ADALBERTO J. SANTOS

Montevideo

Congreso; 22nd International Congress of Arachnology; 2023

International Society of Arachnology

Micrathena, a charismatic spider genus, is a model for a variety of evolutionary biology studies. Its 117 species are recognizable by their remarkable abdominal spines and notable sexual dimorphism. The genus was revised by Levi in 1985, but some of its species groups remain problematic. The triangularispinosa group contains 13 species with polymorphic morphology and wide distributions, and its specimens often cannot be reliably identified, hampering evolutionary and biogeographic studies. To revise the taxonomy of the triangularispinosa species group, we gathered more than 2000 samples from taxonomic collections and extensive field expeditions covering the entire distribution of the group from Costa Rica to Argentina. We sorted those specimens into 34 morphospecies based on somatic and genitalic morphology. Ten of those morphotypes are new, undescribed species; three names will be revalidated; one recently described species will be synonymized; and the remaining morphotypes are geographically structured variations within nominal valid species. Some of those morphospecies have been confirmed by COI sequences and will be further refined by an expansion of this dataset. Most of the undescribed species are restricted to the Andes (N=5), and western Lowland Amazon (N=4), indicating high diversification rate of the genus in those regions. We find some species endemic to the dry diagonal and the Atlantic Forest in Brazil, the Colombian Chocó, and the eastern Lowland Amazon. Our results indicate that even though Levi's revisions are the pavement for the development of Neotropical Araneidae taxonomy, we should take some of his taxonomic proposals with a grain of salt.