The taxonomic status of Farlowella colombiensis Retzer & Page 1997 with comments on species of the F. acus species group (Loricariidae: Loricariinae).

The genus Farlowella has been historically challenging, in part due to the difficulty in defining diagnostic characters which allow to clearly set apart and identify the species. Farlowella colombiensis Retzer & Page 1997 is one of such examples, whose diagnostic characters were based on caudal-fin colour pattern, body cover ventral pattern, and details of the head. We herein reassess the taxonomic status of this species against congeners of the F. acus species group (F. acus, F. martini, F. mitoupibo, F. venezuelensis, and F. vittata). We found no significant differences between F. colombiensis and F. acus in morphometric, meristic, and discrete characters, therefore rendering Farlowella colombiensis a junior synonym of Farlowella acus. We provide remarks on different species of the F. acus group in Colombia, as well as description of sexual dimorphism in the genital papilla for the first time in the subfamily. We also provide a key to the species of the F. acus species group in Colombia.