Chrysallida stefanisi: General description (after 24 shells from 7 localities). — The shell is compact, some¬what conical and scalariform, with a blunt top. The protoconch is of type B, tending to C. There are three slightly convex teleoconch whorls; the last one is high. They strongly constrict near the upper sutures, which makes the shell scalariform. The suture is deep and oblique. The ribs are variable in number and breadth, the interstices therefore likewise, more than twice as broad as the ribs to even narrower than the ribs. These are vertical and straight or hardly curved. On the last whorl, around the periphery, the ribs become narrow and vague but, continuing to the base, always visible. Sometimes the ribs are not only narrow, but also high and sharp. On the upper side of all whorls, on the shoulder, they are bent inwards, meeting the shell-axis at an angle of 90°, deep within the suture so that this has a serrated appearance. With the exception of the protoconch, the whole shell is covered with spiral ridges, crossing the ribs. They are broad and very flat (ribbon-like), close together; the spaces between are only excavated lines. Therefore it seems to the superficial observer, that the spirals are only thin lines. The aperture is oval, there is a very faint tooth-pleat, only visible on turning the shell. On some specimens there are about eight lamella-like pleats, inside the outer lip. There is a clear umbilical groove, on juveniles even a round umbilicus.
Length: 2.1-2.8 mm, LW 65-71%, A 37-41%, L/B 1.8-1.9, B/b 2.1-2.4 (based on 11 shells).

AS Chrysallida stefanisi
Habitat: it lives in the infralittoral and circalittoral zones. It is collected in remarkable depths too.
Distribution: it is found in several localities of the Mediterranean but always rare, found at Cannizzaro (Catania - Sicily - Italy), at 45 m depth.
Notes: this species is not much slim in outline, whorls quite convex, scalariform, suture deep and oblique. More or less slim in aspect but last whorl always overcomes 60% of total height. Protoconch is type B tending to type C. Axial sculpture is made by a variable number of little ribs, narrower than interspaces, continuing, quite visible, up to the base. Spiral sculpture, covering the whole shell surface, crossing axial ribs too, is made by striae fine, incised, serrated among them.
Aperture oval in form. On columella is just visible one small tooth. Small teeth can be present inside external lip too. Umbilicus is typically large and quite visible also in immature specimens. Its peculiar spiral sculpture and its large umbilicus make it easily recognizable from its similar ones. It is not yet clear whether C pygmaea (Grateloup, 1838) is to be considered as a synonym of this species. Average measures of adult specimens are around 1.5-2 mm in height.

Chrysallida stefanisi: By its many clear spiral ridges over the total height of all whorls, C. stefanisi can only be confused with C. maiae, C. fischeri and to a lesser degree C. sigmoidea and C. decussata. According to Van Aartsen (1977), the last-mentioned species has spiral ridges all over the whorls; in fact, the uppermost part of the lower whorls bears no spirals and the first teleoconch whorl is smooth. The shell is oval-conical, only slightly turreted (not clearly scalariform) and has a pointed top.
C. maiae is much more compact, larger, has an oval-conical profile with a pointed top. The spiral ridges are separate spiral threads, only between the ribs, and there is a pronounced tooth. C. stefanisi has an insignificant tooth-pleat, ribbon-like spiral ridges, crossing the ribs, a blunt top and a scalariform profile. C. sigmoidea is slender, cylindrical, with a short last whorl (LW 47% versus 64%). The ribs are sinuous, not straight, the spiral ridges only striae, close together and not ribbon-like.

Chrysallida stefanisi: A rare species, probably only from deep water in the Mediterranean and around the Canary Islands, Madeira and the Azores.