Setia ugesae: — (1) Length about 1.3 to 1.6 mm.
— (2) The shells are transparent and rather glossy, with a light yellowish hue, and decorated with spiral rows of darker spots. The upper whorls are of the same colour as the lower ones. There is no darker spot at the apex.
— (3) Ornamental sculpture is absent, though in some shells traces of very fine and dense spiral striae are to be seen below the periphery.
— (4) The shells are medium solid. There is no labial rib, nor does the aperture show any other peculiarities.
— (5) Large shells have about 4.2 whorls.
— (6) The umbilical chink is about absent.
— (7) The dimensions of the apex are about d = 0.10-0.12 mm and D = 0.15-0.17 mm.
— (8) Seen from aside in position 1, the nucleus is medium prominent and surrounded by a deep suture. Seen from aside in position 2, the nucleus and first ¼ whorl form a high, somewhat flattened segment of a sphere, circumscribed by a deep suture.
— (9) At a magnification of 40 x , no ornamental sculpture can be seen on the protoconch, except that it has a frosted appearance.

A detailed description was provided by VERDUIN (1988, original descriptions).
Shells here studied pupoid oval, fragile, with about four whorls reaching up to 1.3 x 0.7 mm. The last whorl occupies somewhat more than 70% of the total and the aperture about 45%. Outer lip rather thin. Surface smooth; with faint spiral lines seen only under high magnification. There is a subsutural rim characteristic of the species of Crisilla. Yellowish shell with four spiral rows of large reddish spots. Paucispiral protoconch with 1.5 apparently smooth whorls. Only in very well preserved shells can the surface be seen somewhat irregularly rough on the early part. A very thin spiral cord appears in some of the specimens studied.

VERDUIN (1988) described Setia ugesae from specimens collected in El Hierro Island (Canaries). He highlighted the absence of ornamentation of its shell, except for the presence of very fine and dense spiral striations at the base of the shell, which supported its inclusion in the genus Setia. Nevertheless the detailed examination of the shell reveals its resemblance to other species of Crisilla, such as C. innominata, C. postrema, C. perminima or C. spadix, all of them with a weak spiral sculpture. Therefore we consider that it should be better included in the latter genus. The specimens here studied from Selvagens Islands coincide with the original description of this species, although they present a fourth row of brown spots on the base. ALBUQUERQUE ET AL. (2009) had already recorded this species in the Selvagens Islands.

Only empty shells are known from El Hierro (Canary Islands) and Selvagens Islands, from shallow-water down to 20 m in depth.