Chrysallida pirinthella: General description (from literature only). — The shell is small, cylindrical, somewhat turreted, with a blunt top. The protoconch is probably of type C, or type B tending to C. There are four teleoconch whorls, flat in the middle part and strongly bent inwards near the upper and lower suture, which is impressed and oblique. The ribs are straight and almost vertical or slightly prosocline; they continue (?) to the base of the last whorl and are as broad as the interstices. The entire surface of all whorls is covered with spiral ridges, crossing the ribs. The aperture is oval; there is a clear tooth and probably an umbilical chink. Length 1.5-2.0.mm.

In MELVILL (1910) and in BUZZURRO & NOFRONI (1995). Shell very small, subcylindrical, not very solid. Protoconch of type C with a diameter of about 280 µm. Teleoconch with about 3.5 stepped whorls, the last one broadly rounded at the periphery and a high spire (h = 55% H), Suture not very deep, with a subsutural shoulder.
Axial sculpture formed by about 18-20 ribs, rounded in profile, approximately as wide as their interspaces, prolonged attenuated on the base. These ribs are orthocline or slightly prosocline on the last whorl. Spiral sculpture consisting in numerous and very narrow furrows, overriding the ribs. Under great magnification, the surface appears to be rough.
Aperture small, suboval; columella narrow, arched, with a columellar tooth a little internal. Outer lip thin, almost cutting. Shell not umbilicated.
Dimensions of the largest shell figured: 1.63 x 0.6 mm; h = 0.9 mm; A = 0.5 mm.

Chrysallida pirinthella: Because of its many spiral ridges on all the whorls, its more or less cylindrical profile, its small size and its distribution, confusion only may occur with C. fischeri, C. stefanisi
C. fischeri has a pointed top, the protoconch is of type B tending to A, thus less coiled, the whorls are not scalariform, its profile is more pupoid.
C. stefanisi is more compact, the whorls are much more scalariform, the spiral ridges are broad, ribbon-like and the shell has only an insignificant tooth-pleat.

The majority of the previous descriptions or comments related to this species have been tentative and, in our opinion, were wrong except for those of BUZZURRO & NOFROXI (1995) who examined the type material. Probably, the shell described by MELVILL (1910) was not fresh, as was our impression when we examined the holotype; however we believe that our material belongs to this species.
In AARTSEN ET AL. (1989: fig. 5) and in ZENETOS ET AL. (2004) a shell similar to Pyrgulina pirinthella is illustrated, and also GIANNUZZI-SAVELLI ET AL (2014: fig. 220) figured a shell as Pyrgulina cf. pirinthella. In our opinion, all those are very different from the type material examined of this species, and we believe that these shells from the Eastern Mediterranean are more coincident with our P. microtuber n. sp. (see below)
Pyrgulina permanens n. sp. has a rather larger shell with the same number of whorls, is narrower (H /D = 2.6 in front to 2.3 in the holotype of P. pirinthella) with a higher spire, has a less stepped profile, with a subsutural shelf while P. pirinthella has a shoulder, has fewer ribs but more robust, and the columellar tooth, although quite internal, is conspicuous

Chrysallida pirinthella: Persian Gulf, Red Sea. Since 1984 a few specimens have been found in Haifa Bay, Israel.

Karachi, Pakistan. HORNUNG & MERMOD (1924) recorded it from Massaua, Eritrea. We increase its distribution to the infralittoral of the Hurghada, Red Sea.