Taxonomy & naming
Farlowella yarigui was described by Ballen and Mojica in 2014 in Zootaxa (volume 3765, number 2, pages 134–142). The Catalog of Fishes (Eschmeyer, CAS) recognises it as valid (spid 73184). It is placed in the genus Farlowella, the twig or whiptail catfishes, within the subfamily Loricariinae of the family Loricariidae.
The species is assigned to the Farlowella acus species group. It is diagnosed by a median anterior lateral row of plates that is diamond-shaped and by dark interradial membranes on the caudal fin. Its discovery was taxonomically significant on two counts: it is the first trans-Andean species of Farlowella, and the first record of the genus from the Magdalena basin, extending the known range of these catfishes across the Andean cordillera.
The type material comes from the Rio Topon, in the middle Rio Magdalena basin, Santander, Colombia. No synonyms are recognised.
Morphology
Farlowella yarigui reaches a maximum recorded length of about 4.5 in standard length (largest measured specimen, sex undetermined). The body is the elongate, stick-like form typical of the genus, with a long attenuate snout that lends these fish their twig-mimicking camouflage.
Two features distinguish it within the F. acus group: the median anterior lateral row of plates is diamond-shaped, and the membranes between the caudal-fin rays (interradial membranes) are dark. Comprehensive colour-in-life description and full meristic data beyond the diagnostic characters are not detailed in the available sources.
No information on sexual dimorphism has been published for this species. In Farlowella generally, breeding males develop snout odontodes, but this has not been documented specifically for F. yarigui.
Habitat
Farlowella yarigui is known from the Rio Topon, a tributary in the middle Rio Magdalena basin of Colombia. It is a freshwater, benthopelagic fish of tropical waters. Within its river it occupies a restricted microhabitat: individuals were found among wood sticks and partially submerged vegetation in the main channel, and the species appears confined to that niche rather than ranging across the river bed.
Specific water-chemistry measurements (temperature, pH, hardness) are not published for the type locality. The association with submerged wood and marginal vegetation in flowing channel water is consistent with the cryptic, current-favouring habits of twig catfishes generally.
Feeding
The species has a low trophic level of about 2.6, indicating a diet dominated by aufwuchs — the algal and biofilm layer, with associated microfauna and detritus, that coats submerged wood and vegetation. As with other twig catfishes, it presumably rasps this film from surfaces using its ventral sucker-mouth.
No direct feeding or gut-content study specific to F. yarigui has been published; the trophic estimate is the only quantitative dietary indicator available.
Mating
No data on courtship or mating behaviour have been published for Farlowella yarigui. The species has not been the subject of a reproductive study or documented aquarium breeding.
Breeding
No breeding data have been published for this species. Farlowella as a genus are substrate egg-layers with paternal guarding of a clutch laid on a firm surface, but no spawning, clutch size, incubation or parental-care information specific to F. yarigui exists in the literature.
In the aquarium
There is no documented aquarium history for Farlowella yarigui. It is known only from its restricted Magdalena-basin range and has not entered the ornamental trade in any traceable way. Twig catfishes in general demand clean, well-oxygenated water and a steady supply of aufwuchs or vegetable substitutes, but no care guidance specific to this species can be given. No data published.
Conservation
Farlowella yarigui was assessed as Data Deficient by the IUCN Red List in 2014, the same year it was described. The assessment reflects how little is known: the species is documented from a restricted area of the middle Rio Magdalena (Rio Topon), and there is insufficient information on its range, population and threats to assign a more definitive category.
The Magdalena basin is among Colombia's most heavily impacted river systems, subject to deforestation, pollution, sedimentation and hydropower development. A narrowly distributed, microhabitat-specialist fish such as F. yarigui could be vulnerable to these pressures, but its Data Deficient listing means no firm conclusion about its conservation status can yet be drawn.