The
shell of this species slightly larger than that of
Pupilla muscorum, with slightly more prominent growth lines, around 6 not very convex
whorls. The shell
apex is flat (in contrast to
Pupilla muscorum and
Pupilla pratensis). The apertural
lip is weak; the cervical callus is weak; there are usually no teeth in the
aperture, occasionally a weak parietal tooth. Note the presence of a characteristic gutter-like depression in the external surface of the
last whorl, at about 1/4 of the distance from its base. (In oblique light this is also visible in the aperture as a narrow, delicate ridge). The height of the shell is 2.8–3.3 mm. The width of the shell is 1.75–1.8 mm. (
Description of Pupilla pratensis) The
shell of this species is dark to brown, translucent and thin, with fine and distinct growth lines, 6–7.5
whorls with deep
suture, outline elongate and broad,
aperture rounded with weakly developed lip, usually toothless, or with weak parietal and occasionally a palatal tooth, sometimes with weak cervical callus. The height of the shell is 3.5-4.5 mm. The width of the shell is 1.85-2.05 mm.
Pupilla pratensis differs from
Pupilla muscorum, with which it often lives
sympatrically, in its thinner, larger and broader shell, darker and less variable colour and weaker apertural lip. The shell of
Pupilla pratensis is larger – especially in diameter (1.86–2.06 mm), but often also in height (3.48–4.54 mm) – and the number of whorls (6.0–7.5) is usually greater compared to that of
Pupila muscorum. The form is cylindrical in both species, but in
Pupilla muscorum the
last whorls converge rather smoothly towards the
apex; in
Pupilla pratensis the convergence is somewhat more abrupt, giving the apex a blunt appearance. The whorls are usually more vaulted in
Pupilla pratensis, and the
suture is somewhat deeper. The colour of the shell varies from brown to brown-grey in both species, but
Pupilla pratensis is often more of a darkish chestnut brown. In
Pupilla muscorum the colour is more variable, ranging from reddish brown to horny grey. The shell surface is nearly smooth in both species. It appears thinner in
Pupilla pratensis, in which it is sometimes slightly translucent. The growth-lines are very fine in
Pupilla muscorum and somewhat coarser in
Pupilla pratensis. The apertural
lip is often rather weakly developed in
Pupilla pratensis in contrast to
Pupilla muscorum, in which it is thicker and more pronounced. The apertural teeth are more weakly developed in
Pupilla pratensis, and always arise directly from the apertural walls, never from a callus (as is sometimes the case in
Pupilla muscorum). A weakly developed parietal tooth is rather frequently present, often together with a very weak, simply indicated palatal, but the mouth is often completely toothless. It should be remarked, that in some samples from western and northern Norway some specimens of
Pupilla muscorum seem to be larger than in Swedish and German populations, and hence in size close to
Pupilla pratensis – this requires further studies. ==Distribution==