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.

摘要：亚马逊河流域拥有全球物种多样性最高的淡水鱼类区系（ichthyofauna），但该流域仍有广袤区域尚未被系统勘探调查。内格罗河（Río Negro）上游支流便是如此，尤其是流经哥伦比亚境内的那些支流。本研究针对哥伦比亚沃佩斯省米图地区——地处沃佩斯河（Río Vaupés）中游流域——采集的鱼类标本进行检视，整理出包含224个物种的名录。本研究鉴定的物种中，10个物种为哥伦比亚境内的首次记录，另有26个物种为哥伦比亚亚马逊地区的新分布记录。本次收录的物种数量约占哥伦比亚亚马逊地区已知鱼类物种多样性的三分之一，同时约占整个亚马逊流域已知鱼类总物种数的十分之一。物种丰富度最高的两个目为脂鲤目（Characiformes，120种）和鲇形目（Siluriformes，65种），其余6个目合计占总物种数的比例不足20%。本次研究的调查区域属于黑水生态系统，这类生境通常被认为是营养匮乏的环境。本研究探讨了若干生态学机制，以期解释该高度多样的鱼类区系如何起源，并得以在低生产力生境中存续。本次整理的物种名录新增了大量新分布记录，补充了迄今为止针对哥伦比亚亚马逊地区鱼类区系的已有研究资料。