Brazilian obligatory subterranean fauna and threats to the hypogean environment

Abstract

The subterranean environment harbors species that are not capable of establishing populations in the epigean environment, i.e., the obligatory subterranean species. These organisms live in a unique selective regime in permanent darkness and usually low food availability, high air humidity in terrestrial habitats, and low temperature range allied to other unique conditions related to lithologies and past climatic influences. The pressure to increase Brazil’s economic growth relies on agricultural/pastoral industries and exporting of raw materials such as iron, limestone, ethanol, soybean, cotton, and meat, as well as huge reservoir constructions to generate electricity. Mining (even on a small scale), agricultural expansion, and hydroelectric projects are extremely harmful to subterranean biodiversity, via the modification and even destruction of hypogean habitats. The Brazilian subterranean species were analyzed with respect to their distributions, presence on the IUCN Red List, and current and potential threats to hypogean habitats. A map and three lists are presented, one with the described obligatory subterranean species, one with undescribed taxa, and one with the current and potential threats to the hypogean environment. To date, 150 obligatory subterranean species have been recorded in Brazil, plus at least 156 undescribed troglomorphic taxa, totaling 306 Brazilian troglobites/obligatory cave fauna. We also analyzed the current and potential cave threats and the conservation actions that are underway to attempt to compensate for loss of these habitats. In according to the Brazilian legislation (Decree 6640) only caves of maximum relevance are fully protected. One strategy to protect the subterranean fauna of Brazil is the inclusion of these species in the IUCN Red List (one of attributes that determines maximum relevance for caves); however, one of the IUCN assumptions is that the taxa must be formally described. It is clear that the description and proposed protection of Brazilian subterranean biodiversity depends on more systematics studies.

Diversity of Potamolithus (Littorinimorpha, Truncatelloidea) in a high-diversity spot for troglobites in southeastern Brazil: role of habitat fragmentation in the origin of subterranean fauna, and conservation status

“…Below we present an identification key to the Potamolithus from the Alto Ribeira karst area in São Paulo State: With more than 60 troglobitic species, the Alto Ribeira is a high-diversity area for troglobites (sensu Trajano et al 2016, Gallão andBichuette 2018). This is among the highest genetic diversities recorded for Brazil, and is likely related to three factors: the high degree of habitat fragmentation, limited mobility leading to low capacity for dispersal, and habitat preferences.…”

Cave-dwelling pholcid spiders (Araneae, Pholcidae): a review

“…The historical bias of speleology and taxonomy towards European and North American cave faunas is uncontested (cf. Moldovan 2012, Deharveng and Bedos 2012, Gallão and Bichuette 2018. Nevertheless, for certain taxa such as most insects the trend towards a relatively low diversity in tropical caves does not seem to disappear with a more comprehensive study of tropical faunas.…”

“…According to "around 1000 troglobiomorphic spiders have been classified as troglobionts". However, a recent overview of the Brazilian obligatory subterranean fauna found that over 50% of troglobionts available in collections remain undescribed (Gallão and Bichuette 2018), suggesting that the actual number is much higher. Whatever the species numbers, compared to some other major groups like isopods, amphipods, carabid and leiodid beetles, salamanders, and fish, subterranean spiders have rarely been studied in much detail or propagated as model organisms for particular questions concerning evolution in subterranean environments (for exceptions, see .…”

Pseudonannolene canastra sp. nov. (Diplopoda, Spirostreptida) – a new troglobitic millipede from the southwestern state of Minas Gerais, Brazil

“…In addition to P. canastra sp. nov., two more subterranean species are known from the Serra da Canastra (different taxonomic group) that has been sampled by LES team (Laboratório de Estudos Subterrâneos) since 2009 (Gallão and Bichuette 2018). This shows the potential and biospeleological importance of the region, as well as the need for adequate protection and management of the cave, its surroundings, the watershed and landscape (Gallão and Bichuette 2018).…”