Pupilla pratensis is a species of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk or micromollusk in the family Pupillidae. This taxon was elevated to species level in 2009. This species is considered as a synonym of Pupilla alpicola (Charpentier, 1837) Taxonomy Pupilla pratensis was originally described as a variety of Pupilla muscorum by German malacologist Stefan Clessin in 1871. The taxon Pupilla pratensis has long been neglected in the malacological literature, or considered a morphologically weakly defined ecophenotype – found in wet, calcareous habitats – of the variable Pupilla muscorum. The form, however, represents a distinct species, which has recently been shown in a study combining morphological, ecological and molecular data by von Proschwitz et al. (2007, 2009). Pupilla pratensis was misidentified as either Pupilla muscorum or Pupilla alpicola before 2009. However, based on some 2012 preliminary molecular analyses, it seems that Pupilla pratensis and Pupilla alpicola are geographical subspecies of a single, more widely distributed species. Description 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.