Following the Path of Wet Rocks: How Does the Order of Rivers in the Basins of Eastern Brazil Relate to the Distribution of Species of Cycloramphus (Anura: Cycloramphidae)?
Cycloramphidae, River order, Biogeograpy
The first classifications of rivers by their orders emerged as an attempt to systematically group rivers of similar size, depth and water flow. Among several methodologies developed, the one by Strahler, 1957, stands out, widely used in studies focused on hydrological issues, and also in studies on biodiversity. Through the cartographic representation of the distribution of Cycloramphus species (Anura: Cycloramphidae) for the species that reproduce in streams, this study correlates their occurrence with the ordering of rivers by the Strahler, 1957 system in the states of Rio de Janeiro and São Paulo. Geographically distant and isolated occurrences on islands of populations of the same species are also evaluated. The geographic points were collected through the SpeciesLink platform, in published articles and in specimens deposited at the Laboratory of Natural History, Comparative and Systematic Anatomy of Amphibians at UFRRJ. There are 560 records of twelve species distributed in 87 points. With the representation of rivers, the records show interconnected populations through the drainage network. Insular populations and others that are not connected in the current hydrogeographical pattern are explained through historical environmental alterations, among them and mainly, alteration of the mean sea level. The cartography resulting from this investigation can also serve as a model for predicting the occurrence of this group of cycloramphids in areas not yet sampled, since rivers not yet sampled, in the same hydrographic basin, have great chances of harboring populations of these species. It also discusses problems related to the conservation of environments that are specific to the occurrence of the group, which are wet rocks in rivers with the formation of waterfalls, beginnings of rivers or intermittent rivers, and the riparian vegetation of these environments.