The water mite genus Torrenticola (Hydrachnidia: Torrenticolidae) in Costa Rica – ecology, diversity, and bioindicator potential

Abstract

The genus Torrenticola is found in springs and running waters on all continents except Antarctica, with the highest diversity in the Tropics and Northern Temperate regions. In Costa Rican streams and springs it is the most frequent and abundant water mite genus In a recent study 36 new species were described, raising the number of species known from Costa Rica to 42; furthermore, ecological data of >3,000 specimens from >200 sample sites were analysed. Based on these data, the first ecological analyses on Neotropical water mites are presented. Torrenticola spp. were found in all types of springs and running waters all over Costa Rica, but at species level differential habitat demands and distribution patterns are apparent. Analyses of habitat preferences of the species revealed linkages of particular species to certain habitat types (springs, large rivers, etc.), different sensitivity of the species towards pollution, and a distinct altitudinal zonation. These results demonstrate the great potential of this group of mites in the monitoring of aquatic habitats. The finding of up to seven species of the genus at a single locality allows the study of microhabitat specificity and niche-differentiation, as well as general patterns of species assemblages. High mountain regions could be determined as main centres of diversity and endemism. Furthermore, idiosoma size was found to differ among species and between sexes, and to vary with habitat and elevation. Finally, the state of knowledge on the diversity and general distribution patterns of the genus in the New World is described and discussed.