We discuss new applications of baited remote underwater video (BRUV) systems based on recordings of Amazonian freshwater fauna during a long-term fish monitoring program in the Xingu River, Brazil. BRUVs facilitated estimates of relative abundance and frequency of occurrence for species of river turtles (Podocnemis unifilis, P. expansa, Rhinoclemmys punctularia), river dolphin (Inia geoffrensis) and

Herbivorous fishes feed on stems, leaves, flowers, seeds, fruits, and nuts of diverse aquatic plants, as well as algae. Pacus are the herbivorous cousins of piranhas and consume a myriad of diets comprised of these plant products, but a few species are phytophages, herbivores that feed almost exclusively on rapids-dwelling (rheophilic) riverweed plants from the family Podostemaceae. The degree to which

A new species of Bryconops is described from the rio Xingu Basin, Brazil, that differs from all congeners by the following combination of characters: predorsal scales 8–9, perforated scales in the lateral line 43–45, and pigmentation pattern composed of wide silvery midlateral band on body, hyaline dorsal and anal fins (in alcohol), and dark blotch on distal half of dorsal caudal-fin lobe. The new

A new species of Creagrutus is described from the upper rio Xingu basin, Mato Grosso state, Brazil. The new species can be distinguished from its congeners by a combination of characters that includes dorsal fin mostly black, a dark oblique blotch on middle and upper-inferior caudal-fin rays, and presence of only two rows of premaxillary teeth. Creagrutus mucipu, formerly known only from the upper

During a pilot survey, sponges and mollusks were sampled from the bottom of the middle Xingu River (rapids) and lower Xingu River (ria) via hand-picking in shallows and trawling and surface-supplied dives in deeper waters. The survey revealed a benthic community composed of eight sponge species in four genera and three families, and added six species to the Xingu Basin fauna. Sponges exhibited distinct

RheodreissenaGeda et al. 2018, a recently described genus of Dreissenidae, is represented by living species that inhabit inland freshwaters of Brazil and Venezuela. The type species of Rheodreissena is R. hoeblichi (Schütt 1991a) described from the lower Orinoco basin, Venezuela. Three species are added in this study: R. lopesi (Alvarenga & Ricci, 1989) from the Tocantins and Xingu basins; R. cordilineata

A new species of Platydoras is described from the rio Xingu Basin, Brazil. Platydoras birindellii is distinguished from congeners by having gas bladder simple (vs. with posterior secondary chamber) and dorsal and caudal fins uniformly dusky (vs. with distinct marks composed of dark broad band or blotch on central portion of dorsal fin and pair of dark broad stripes on caudal fin, one central to each

Results are presented on species richness and distribution of the crustacean fauna obtained by iXingu Project expeditions along the middle and lower Xingu River during low and high water seasons primarily from 2013–2014, prior to the completion of the Belo Monte dam complex. The checklist includes the parasitic and decapod crustacean species surveyed in the Xingu River from the mouth of its tributary

A new species of Hyphessobrycon is described from the middle and lower rio Xingu Basin, Pará state, Brazil. The new species can be distinguished from all congeners by the combination of a large caudal peduncle blotch (largest in mature males), absence of humeral blotch, and largest teeth on dentary, inner premaxillary and maxillary relatively compressed with 6–9 cusps. The new species is compared to

Crenicichla dandara, new species, is endemic to the rio Xingu above the Belo Monte narrows, and its major left bank tributary the rio Iriri. The new species is distinguished from all congeners by the following combination of characters: body uniformly black (live fishes) or dark brown (preserved specimens) in adults and 74–86 scales in the E1 row. Crenicichla dandara is considered herein to be the

Trachydoras is a genus of Doradidae (thorny catfishes) with five nominal valid species distributed in lowland areas of the Amazon, Orinoco, Paraná-Paraguay and Essequibo river basins of South America. A sixth species is described here as Trachydoras gepharti and diagnosed by five characteristics unique among congeners: mental barbels thick, tapered and profusely ornamented with many elongate fleshy

A recent survey of the aquatic fauna in the rio Xingu, Pará State, Brazil, revealed a new species of Drulia Gray 1867, an extraordinary genus of freshwater sponge endemic to South America. Drulia cristinae n. sp. is distinguished in part by having gemmoscleres typically with elliptical outline and outer face with small, central crest or irregular bulge (exceptionally nude), oscules set atop conical