Otothyropsis marapoama is described from the Marapoama drainage within the upper Tietê River system of São Paulo state, Brazil. It belongs to the genus Otothyropsis, a small group of otothyrine loricariids characterised by relatively large eyes and compact bodies adapted for rocky fast-flowing streams. The species name marapoama refers to its type locality. It is an Atlantic Forest endemic with restricted distribution and limited export history.
In its natural habitat, O. marapoama inhabits swift, clear, well-oxygenated tributaries with rocky substrates where periphyton growth is abundant. The upper Tietê and its tributaries drain the Serra da Mantiqueira and São Paulo highland plateau — a region of moderately hard, cool water with significant seasonal variation in flow. The species uses its adhesive disc to maintain position in current and grazes actively throughout the day on periphyton and fine algae.
For aquarists, O. marapoama is a rare and scientifically significant species for the well-maintained cool planted aquarium. Its preference for clear, moderately cool, fast-flowing water and rocky substrate requires an appropriately equipped setup, placing its care in the advanced category despite its modest size. Collectors interested in Atlantic Forest catfishes or the biodiversity of the Tietê drainage will find it a particularly rewarding subject.
