Pupillidae

Pupillidae is a family of very small land snails, terrestrial pulmonate gastropods. Members are commonly called pupillids and are characterized by their tiny shells and compact appearance. The family is placed in the superfamily Pupilloidea within the larger group of land snails, and it includes several genera, with Pupilla and Columella among the best known.

Morphology and anatomy

Shells in Pupillidae are typically minute, often only 1–5 millimeters in height, and range from elongated to somewhat hemispherical in shape. The surface is usually smooth or only faintly sculptured, and the aperture is simple with a thin, sometimes lightly expanded peristome. The umbilicus in many species is narrow or absent. The overall form and small size contribute to the micro-mollusk habit of these snails, which are often overlooked in broader surveys.

Distribution and habitat

Pupillidae has a widespread but mostly temperate distribution, occurring in Europe, Asia, and North America, with various species adapted to local climates. They prefer moist microhabitats such as leaf litter, moss, rotting wood, and soil in forests, grasslands, and sometimes scree or caves. Some species can tolerate drier crevices or rocky habitats, but most require consistent moisture and shade to prevent desiccation.

Ecology and life history

As detritivores and micro-grazers, pupillids feed on fungal matter, algae, and decomposing organic material on the surfaces they inhabit. Reproduction is typically sexual, with direct development from eggs into small adults, bypassing a free-living larval stage. Life cycles are short and population dynamics often reflect the availability of suitable moisture and shelter.

Genera

Notable genera within Pupillidae include Pupilla and Columella. The taxonomy of the group has undergone revisions, and regional faunas may recognize additional genera or synonyms.