Mitromorpha mirim is a species of sea snail, a marine gastropod mollusk in the family Mitromorphidae.
The shell reaches a length of up to 3.7 mm and is fusiform in outline, with the width approximately half the shell length. Shell colour is uniformly pale beige, with a whitish band near the suture. The protoconch is paucispiral (spiral with few turns), consisting of about 1.5 smooth, glossy whorls and forming roughly 10% of the total shell length.
The teleoconch comprises about four whorls and is sculptured with spiral cords and axial undulations, producing a weak reticulate pattern. The subsutural cord is slightly larger and more nodulose than the remaining sculpture. The aperture is elongated, accounting for about 60% of the shell length. The outer lip is internally lirate, bearing four to five weak spiral cords, while the inner lip shows a pair of low columellar folds. The siphonal canal is short and slightly projected forward.
This marine species occurs off EspÃÂrito Santo, Brazil, on the continental slope of the Abrolhos region.
The species inhabits sandy-mud bottoms at depths between 60 and 105 m (197 and 345 ft).
The specific name mirim is derived from the TupiâÂÂGuarani word meaning âÂÂsmallâÂÂ, referring to the small size of the shell.