Fishes of the Mitú Region: middle basin of the río Vaupés, Colombian Amazon

Abstract

The Amazon River basin hosts the most diverse freshwater ichthyofauna in the world, and yet huge areas of the basin remain unexplored. This is the case for the upper tributaries of the rio Negro, especially those draining the Colombian territory. Here we present a list of 224 species derived from the examination of specimens collected in the Mitú region (Vaupés Department, Colombia), the middle basin of the río Vaupés. Of the species identified in our study, 10 species are recorded from Colombia for the first time, and 26 species are newly recorded from the Colombian Amazon. The number of species we present here comprise almost one-third of the known species diversity of the Colombian Amazon and nearly a tenth of the total number of those known across the entirety of the Amazon basin. The most diverse orders were Characiformes (120 species) and Siluriformes (65 species), and the remaining six orders comprised less than 20% of total species. The study area comprised blackwater systems, which are considered to be nutrient-poor environments. We discuss some ecological aspects that might explain how this highly diverse ichthyofauna originates and is maintain in less productive systems. The list presented here adds an important number of new records and complements the information derived from previous studies, carried out thus far with regards to the fish fauna of the Colombian Amazon.

A new species of rheophilic armored catfish of Rineloricaria (Siluriformes: Loricariidae) from the Vaupés River, Amazonas basin, Colombia

“…Its dark‐colored waters (black‐brown), acidic, with a large number of humic acids, and poor in dissolved inorganic substances, explain the low levels of nutrients (Cabalzar & Lima, 2005). The substrate is mainly sand (with beaches in the low water period) and rock (Bogotá‐Gregory et al, 2022); the latter, in rocky outcrops that give way to innumerable cachiveras that serve as habitat and act as a natural barrier for fish dispersal (Lima et al, 2005). Few species belonging to Rineloricaria are found in environments with such characteristics, and one example is R .…”

Fishes (Actinopterygii) of the rapids and associated environments in the lower Vaupés River Basin: an undiscovered Colombian Amazon diversity

“…represent more than 78% of the total diversity of fish; the remaining orders have between five and nine species (Table 2). In addition, 44 new records are added to the previous list of fishes from the Vaupés River basin of Bogotá-Gregory et al (2022a).…”

“…The western Rio Negro tributaries are known for their distinctive rheophilic fish fauna (Lima et al 2005). A total of 224 fish species are known to occur in the Vaupés River in Colombia (Bogotá-Gregory et al 2020, 2022a; some of these species are endemic to this basin, while others are widely distributed in the Amazon basin and adjacent basins such as the Orinoco and those within the Guiana Shield (van der Sleen and Albert 2017; Beltrão et al 2019;Bogotá-Gregory et al 2020, 2022a, 2022bTaphorn et al 2022).…”

“…Recent studies evaluating the sampling efforts to inventory Amazon River basin ichthyofauna reveal that extensive areas in southwestern Colombia remain almost unsampled (Jézéquel et al 2020a). Recent reviews purported new records for the basin and Colombia suggesting that the biodiversity knowledge of the area is still incipient (Bogotá-Gregory et al 2020, 2022a.…”

Identifying the current and future status of freshwater connectivity corridors in the Amazon Basin

“…Short‐distance fish migrants and residents (<500 km) form a large group of generally small species (<20 cm) that may be abundant from the mainstem to the upper courses of tributaries (Bogotá‐Gregory et al, 2022; Duponchelle et al, 2021) where they overlap somehow with long‐distance migratory species or even in small upland forest streams (Beltrão et al, 2019). However, with some local exceptions, their migrations are poorly understood as they are not commonly captured by commercial fishing.…”