Biodiversidade de opiliões na área de preservação permanente do lago de Itaipu em Santa Helena, Paraná

Abstract

Opiliones belong to the fourth-largest order of the Arachnida class, with approximately 6,000 species described. They play a relevant ecological role in terrestrial ecosystems, as scavengers and predators of small arthropods, decomposing matter, and worms. This study aimed to survey harvestmen species in a section of Lake Itaipu's Permanent Preservation Area (PPA), located in Santa Helena, Paraná. Collections were carried out monthly, between April and October 2024, in three contiguous environments of the PPA: reforestation area with mango trees, area in regeneration, and area bordering the lake. The harvestmen collected were placed in lethal vials containing ethyl acetate and then in vials containing 70% ethyl alcohol for later identification by a specialist down to the lowest taxonomic level. In total, 331 individuals were collected, 131 in the reforestation environment with mango trees, 106 in the regeneration area, and 94 in the riverside area. In total, four species were identified (Eusarcus hastatus, Geraeocormobius sylvarum, Gryne sp1, and Pachylinae), all found in the three areas evaluated, except Gryne sp1, which was not found in the regeneration area. The most incredible abundance of individuals was recorded in May, and the lowest in October. Eight individuals of Geraeocormobius sylvarum were collected during feeding activity, and their prey were: annelids (01), leaf-cutter ants of the genus Atta (01), ants of the genus Pachycondyla (01), mayflies (01), wasps (01) and a mass of an unidentified arthropod structure (01). Two other prey items could not be identified due to the small size of the structures found in the chelicerae. The results highlight this group of arthropods in Santa Helena and contribute to understanding the local biodiversity that is still unknown.