Abstract
Harvestmen are arachnids that play an important role in organic matter breakdown. However, there are many ecosystems in Brazil, including Conservation Units, which lack information about these organisms or are sub-sampled. Even in areas of Atlantic forest, a biome that hosts the greatest diversity and endemic rates of these arthropods in the world. In this perspective, the purpose of this study was to survey the harvestmen fauna in areas of Semideciduous Seasonal Forest in the Ilha Grande National Park, Paraná, southern Brazil, from February to November 2019, totaling 15 days and 60 hours, on six islands in the Paraná River. A total of 170 specimens was collected, distributed in five genera, comprising two species and three morphotypes. The low species richness may reflect the isolation of populations imposed by the island effect, however the study expanded the geographic distribution of Parapachyloides uncinatus and Discocyrtus invalidus, for which until then there was no record of occurrence in the Paraná State.
Highlights
Harvestmen comprise an Order of the Class Arachnida, known in Brazil as bodum, aranha-alho or aranha-bode, due to odorous secretions used as defense mechanisms (Machado, Pinto-da-Rocha, & Giribet, 2007)
The park consists of approximately 180 islands, in addition to sandbanks, natural lagoons and freshwater swamps, totalizing 76,033 hectares (Ministério do Meio Ambiente [MMA] & Instituto Chico Mendes de Conservação da Biodiversidade [ICMBio], 2008). It protects two types of environment belonging to the Atlantic Forest Biome: Semideciduous Seasonal Forest and pioneer formations with fluviallacustrine influence
Two taxa were considered rare (Table 1), and the Chao 1 index estimated 6 ± 0.83 species for the sampled area, the Jackknife 2 index estimated 8.21 ± 1.81 species, and for Mao Tau index, the richness was estimated at 7 ± 1.53 species (Figure 3)
Summary
Many species of harvestmen require high levels of humidity to survive, so they are directly influenced by microclimate conditions, which restricts these animals to humid and shaded habitats (Machado et al, 2007; Santos, 2007; Ferreira, Pinheiro, Ázara, Clemente, & Souza, 2020) They can live buried in the soil, under litter, under stones and bark, in moss patches, bromeliads, or even in caves (Machado et al, 2007). They are omnivores and can feed on other invertebrates, plants and decomposing animals, facilitating nutrient cycling and playing an important role in organic matter breakdown (Moore, Hunt, & Elliott, 1991; Resende, Pinto-da-Rocha, & Bragagnolo, 2012; Giribet & Sharma, 2015)
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