Studies focusing cave fauna on granitic caves are relatively rare when compared to carbonatic ones and no one considered replicas in the sampling to test fauna distribution patterns. We describe the terrestrial fauna of Riacho Subterrâneo cave through four sampling occasions (replicas) in different seasons. We analyzed seasonality and substrate preference of terrestrial invertebrates and discussed the importance of this neglected habitat as a refuge for fauna. Furthermore, we stressed the importance of the replicas in order to detect subterranean biodiversity patterns. The cave represents the greatest richness considering igneous rocks in Brazil (199 taxa) and has an important role as refuge for epigean fauna, besides the maintenance of troglophilic and trogloxene populations.
The karst area of the northeastern state of Goiás comprises two main municipalities: São Domingos and Posse. São Domingos is inside the limits of a Full Protection Conservation Unit known as Parque Estadual de Terra Ronca (PETeR), where a high number of caves occurs, some of them surpassing 10 km in length. Despite their protection by law, uncontrolled tourism has been threatening the integrity of the unique and fragile cave systems of São Domingos. On the other hand, the caves of Posse are much less visited, with its subterranean fauna poorly unknown and are strongly threatened by the urban areas and mining activities in the vicinity. We conducted six systematic surveys of invertebrates in 12 caves, seven of which are located in São Domingos and five in Posse, between 2010 and 2012. Immediately outside the caves, we sampled several microhabitats for comparison. We estimated richness, abundance, and taxonomic distinctness of the communities. We recorded 1,941 individuals of 344 morphospecies. Caves from São Domingos showed a higher species richness and were more taxonomic distinct than caves from Posse. Most morphospecies were considered troglophiles (188). We also found one trogloxene and one troglobite, as well as nine troglomorphic taxa that possibly are troglobitic as well. Both regions have markedly singular caves regarding its subterranean fauna, with high values of taxonomic distinctness. However, the richer caves were not necessarily the most taxonomic distinct. Conservation measures are especially necessary in the region of Posse, where caves are not legally protected and are within an area of significant urbanization. Cave entrances of Posse are near deforested vicinities, in some cases with domestic wastes and cement plants nearby.
The food base in the subterranean environment consists mainly of allochthonous materials. In this environment the resources are distributed generally in a heterogeneous dispersed way and the distribution of resources and their availability determine where the terrestrial invertebrates will reside, which is important for understanding ecological relationships and to establish conservation strategies. Thus, we tested how the complexity of substrates influences the richness and composition of the subterranean terrestrial invertebrates in the Presidente Olegário karst area, southeastern Brazil. We carried out collections in six caves during both dry and wet seasons, using combined collection methods. We observed different distributions in relation to the substrate, because the environmental heterogeneity increases the amount of available niches for the fauna. Some taxa showed a preference for specific substrates, probably related to the availability of food resources and humidity and to body size restriction, emphasizing the niche differentiation between species. Anthropogenic impacts can cause irreversible alterations in the subterranean fauna because the subterranean environment is dependent on the surface for input of trophic resources. On-going impacts in the Presidente Olegario karst area, like agriculture, pastures, gas extraction, and hydroelectric projects, are therefore a serious threat to subterranean biodiversity and this region should be prioritized for conservation.
Emesine bugs, within several genera, are recorded from caves around the world, but have been regarded as uncommon in these habitats. Many emesines have ecological relationships with spiders, as kleptoparasites, predators, or both. However, cave emesines are apparently rarely involved in these arachnophilous relationships, and only two examples have been previously documented. Recent studies in limestone caves at Presidente Olegário in northwestern Minas Gerais, Southeastern Brazil revealed the presence of four emesine species, two of which (Emesa mourei Wygodzinsky, 1946 and Phasmatocoris sp.) were associated with spiders, probably as kleptoparasites. The spiders recorded in these associations were Mesabolivar aff. tandilicus (Mello-Leitão, 1940) (Pholcidae) and Loxosceles similis Moenkhaus, 1898 (Sicariidae). The only non-emesine reduviid recorded in Presidente Olegário caves was Zelurus zikani (Costa Lima, 1940). We discuss these rarely recorded associations between cave emesines and spiders and the importance of protecting Presidente Olegário caves.
Since its description, the troglobitic amphipod Hyalella veredae Cardoso & Bueno, 2014 has been recorded only in its type locality, Vereda da Palha cave, in southeastern Brazil. We report this species from three other caves in the region, expanding its distribution by at least 20 km². Inter- and intra-population variability in eye size was observed. Two caves had larger populations, probably due to the presence of biofilm. The species was classified as Critically Endangered due to its restricted area of occurrence, and regional impacts and threats.
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