As the name elongata is preoccupied by Columbella rustica var. elongata Philippi, 1836, we introduce Mitrella longissima as a nomen novum. Pace (1902) also mentioned elongata Lamarck without stating a year of publication and further comments. We were not able to trace a Columbella elongata described by Lamarck, as this would then be the senior name and not the one Philippi introduced. The classification of this species in the genus Mitrella is evident, but it fits none of the subgenera known in this genus. We therefore leave the subgeneric placement of this species open for further study. Mitrella boucheti Drivas & Jay. 1990 is a closely related species.

Shell of moderate size for the genus (9 mm - 11 mm), fusiform, very elongate. Teleoconch consisting of about 8 whorls; protoconch multispiral, consisting of 2.5-3 whorls; transition to teleoconch not clearly visible. Teleoconch whorls all completely smooth. Suture straight, shallow. Body whorl about 50% of total shell length, with 11-13 basal cords. Outer lip not thickened, smooth outside, without denticles on the apertural side. Columellar callus hardly noticeable or absent. No columellar denticles.
Shell colour off-white to bright orange, upper whorls and protoconch lighter coloured with a pattern of very fine, brown, wavy lines, which are not clearly visible in all specimens. Aperture and columella in the same colour. Type material: Holotype ZMA 3.11.059 (length: 10.57 mm: width: 3.43 mm)

Known from Indonesia (type locality). Further material known from the central Philippines (Cebu. Mactan Island area; collection K. Monsecour). Type locality: Stat. 162, Indonesia, between Loslos and Broken-islands. West coast of Salawatti. 18 m. coarse and line sand with clay and shells.