| Biology: |
Generally found associated with rocky substrate. Young individuals were observed foraging during day and night, the larger ones were more active at night, being generally observed hiding in cavities at the margins of the stream during day. For juveniles, the smallest specimens (approximately 2,0 cm TL), were usually found in the fast currents of waterfalls in small rivers and streams, not hiding but foraging on rock formations in open water. However, these young specimens seem to prefer shaded areas, and are clearly diurnal. Middle-sized specimens (approximately 10.0 cm TL) were not observed in the waterfalls, inhabiting other parts of the small rivers and streams, usually hiding under rocks and driftwood. Although large specimens (approximately 60.0 cm TL) were observed in shallow waters, shoals were observed in deeper areas. Adult shoals are formed up to several hundred specimens, usually resting and feeding on the steep rocky shelves from one meter to more than 10 meters deep. It has been observed that the new species graze on hard substrates, from which they remove the periphytic matrix by scraping it. In the main rivers they seem to use rocky and clay cave formations as breeding sites. Both soft and hardened clay caves are used, with holes in the areas of soft clay substrate, apparently dug by large specimens. Contrary to the observation by Penatti (2010), larger adults were observed active during day (P. Petersen, pers. Comm., video file by Peter Petersen showing the new species in its natural habitat, the rio da Prata, is available at https://youtu.be/QJ62856SlIo). This species occurs with three congeners, H. basilisko, H. cochliodonand an undescribed species referred here as Hypostomus aff. ancistroides (Ref. 123771). |
