RESUMO
To date, approximately 190 species of terrestrial isopods are known from Brazil and only 14 are considered troglobiotic. After the examination of a large collection from caves in Bambuí and Una geomorphological areas, along the states of Bahia, Minas Gerais and Goiás, two new troglobiotic species were recognized. Pectenoniscus liliae Campos-Filho, Bichuette Taiti sp. n. (Styloniscidae) is described from Serra do Ramalho karst area, and Benthana xiquinhoi Campos-Filho, Bichuette Taiti sp. n. (Philosciidae) from sandstone caves of Chapada Diamantina region. The latter constitutes the second troglomorphic species of the genus. Xangoniscus aganju (Styloniscidae) is also recorded from two caves in the Serra do Ramalho karst area. The systematic position of Iuiuniscus iuiuensis is briefly discussed and Venezillo congener (Armadillidae) is redescribed from São Domingos karst area.
Assuntos
Isópodes , Animais , Brasil , MalpighialesRESUMO
The new species Cylindroniscus platoi n. sp. is herein described. As far as known, the species occurs only in three caves developed in a continuous limestone outcrop at Pedro Leopoldo municipality, Minas Gerais State. Cylindroniscus platoi n. sp. is regarded as an endemic troglobite based on its limited distribution and on non-obvious troglomorphisms found on its body surface.
Assuntos
Cavernas , Isópodes , Animais , Brasil , Carbonato de CálcioRESUMO
Caves are not colonised by all taxa present in the surface species pool, due to absence of light and the tendency to food limitation when compared to surface communities. Under strong species sorting during colonisation and later by the restrictive environmental filter, traits that are not adaptive in subterranean habitats may be filtered out. We tested whether cave communities were assembled by the restrictive regime propitiated by permanent darkness or by competitive exclusion due to resource scarcity. When compared to surface communities, the restrictive subterranean regime would lead to lower functional diversity and phenotypic clustering inside the caves, and the opposite should be expected in the case of competitive exclusion. Using isopods (Oniscidea) as model taxa, we measured several niche descriptors of taxa from surface and cave habitats, used a multivariate measure of functional diversity, and compared their widths. We found phenotypic overdispersion and higher functional diversity in cave taxa when compared to surface taxa. On the one hand, the dry climate outside of caves hampered the survival of several taxa and their ecological strategies, not viable under severe desiccation risk, culminating in the clustering of functional traits. In contrast, this restriction does not occur inside of caves, where isopods find favourable conditions under lower predation pressures and more amenable environmental parameters that allow occupation and subsequent diversification. Our results showed that, at least for some taxa, caves may not be such a harsh environment as previously thought. The high functional diversity we found inside caves adds an additional reason for the conservation of these sensitive environments.