História Natural de Pygidianops sp. (Trichomycteridae, Siluriformes) em um igarapé de terra-firme da Amazônia Central, Brasil

Abstract

The natural history of Pygidianops sp. (Trichomycteridae, Glanapteryginae), an undescribed species of free-living candiru, was studied based on observations of individuals inhabiting a forest stream in Central Amazon. The fish remains buried in the sand of the bottom of the stream all the time, and were never observed emersed during our field observations. The individuals feed on small psammophilous invertebrates, especially mosquito larvae (Chironomidae) and sand-crawling copepods (Harpacticoida), which are probably captured by suction through active hunting amidst the sand grains. Regarding the reproduction, mature females were found all over the year, and presented few and proportionally very large oocytes. The presence and abundance of Pygidianops sp. along the stream seems to be influenced by a combination of local environment factors, such as the sand bank slope, the water flow, channel depth, grain size composition of the sand and, especially, the water flow inside the sand particles, which is very difficult to evaluate. Other biotic characteristics, such as the apparently patchy distribution of prey, possibly influence the occupation of the substrate by individuals of Pygidianops sp.