Hydrolaetare caparu is only known from the type locality, Caparú Ranch (14 48.795 S; 61 09.602 W, 158 masl), Provincia Velasco, Department of Santa Cruz, Bolivia (Jansen et al., 2007). The species may possibly be distributed more widely in adjacent areas with similar habitats (e.g. northern Bolivia and neighbouring areas in Brazil (M. Jansen, pers. comm. 2008).
Habitat and Ecology
This species seems to be restricted to seasonally flooded riparian forests of a small river associated with the Rio Paragua that dries up during the dry season. Occasionally, the species was found in an adjacent flooded grassland area near the borders of the forest. All 17 observations in February 2006 were found near or on small islands formed by roots at the bottom of trees. Twelve individuals were found in the water, five were found on the ground. Calling males were observed on sites close to the waterline or half inside the water with high escape distance (approximately 5–10 m). Other anuran species recorded at this site were Dendropsophus cf. leali, Leptodactylus chaquensis, Osteocephalus sp. and Rhinella cf. margaritifer (Jansen et al., 2007). The species is likely to burrow itself during the dry season (M. Jansen, pers. comm. 2008).
Seventeen individuals were observed in early 2006, while only one subadult was observed in December of the preceding year. A remarkably high density of this species could be observed along 100-m transects: up to three individuals were seen on 11 surveys along the transect (12 observations; average 1.1 per survey), and up to four individuals could be heard (24 observations on 11 visits; average 2.2 per survey). Although H. caparu appeared to be very rare in October 2005, the strikingly high densities of H. caparu during the surveys in January 2006 suggest that this species is highly seasonal in its appearance (Jansen et al., 2007).
A potential threat outside the type locality is habitat fragmentation. Further research is needed to assess its impact on the species (M. Jansen, pers. comm. 2008).
No conservation measures are known for this species.
Hydrolaetare caparu can be distinguished from other congeners by a combination of morphological features, colour pattern and advertisement call features (Jansen et al., 2007).
Martin Jansen 2008. Hydrolaetare caparu. In: IUCN 2014