Sampling
The study is based upon exhaustive sampling carried
in 39 locations at altitudes (expressed as m above sea
level) between 20 and 1,225 m along the entire basin
(Fig. 1). Samples were taken in April 2007 through
July 2007, between October and November 2009, and
in April 2010. In order to describe the presence of
each species and its distribution in the study area, the