Two new Amazonian species of Ancistrus Kner, 1854 (Teleostei: Loricariidae) with vestigial adipose fin, with an appraisal on adipose fin loss in Neotropical armoured catfishes - Oliveira, Renildo Ribeiro de; Pydaniel, Lúcia Helena Rapp; Zawadzki, Cláudio; Zuanon, Jansen Alfredo Sampaio (Ichthyological Exploration of Freshwaters, 2016)