Pleuroceridae

Pleuroceridae, common name pleurocerids, is a family of small to medium-sized freshwater snails, aquatic gilled gastropod mollusks in the superfamily Cerithioidea.These snails have an operculum and typically a robust high-spired shell.

Reproduction is iteroparous, and juvenile snails emerge from eggs laid on a firm surface by a gonochoristic female. There is no veliger stage.

Evolution
There is very high level of mitochondrial heterogeneity in apparent species of Pleuroceridae (highest among gastropods, also with Semisulcospiridae), that has not been sufficiently explained yet as of 2015. However, it has been suggested that this may be due to pleurocerids having very poor dispersal abilities, allowing even slightly separated populations to see great genetic divergence.

Populations of the pleurocerid species in the Old Appalachians (Virginia south to Georgia) are present on both sides of the Eastern Continental Divide, but there is no difference in the extent of intrapopulation heterogeneity on either side, and there is no evidence for cryptic speciation on either side either. Given the age of the Appalachians, it has been suggested that these populations may be extremely ancient, dating back to the Paleozoic when the initial Appalachian orogeny separated them, to the extent that any geographic signal in the test gene for the divergence estimates has been lost. Levels of genetic divergence appear to be lower in the modern center for pleurocerid diversity (the Alabama and Coosa river systems) than in the Old Appalachians, indicating that the latter may represent the ancestral origin of pleurocerids.

Distribution
As currently defined, this family is confined entirely to eastern North American fresh waters. Similar snails formerly classified with Pleuroceridae, but now assigned to other families are widespread in temperate and tropical parts of Southern and Eastern Asia, and Africa. Most require unpolluted rivers and streams, but a few are adapted to living in lakes or reservoirs.

2005 taxonomy
The following two subfamilies have been recognized in the taxonomy of Bouchet & Rocroi (2005):
 * Pleurocerinae P. Fischer, 1885 - synonyms: Ceriphasiinae Gill, 1863; Strepomatidae Haldeman, 1864; Ellipstomatidae Hannibal, 1912; Gyrotominae Hannibal, 1912; Anaplocamidae Dall, 1921
 * Semisulcospirinae Morrison, 1952 - synonym: Jugidae Starobogatov, Prozorova, Bogatov & Sayenko, 2004 (n.a.)

2009 taxonomy
Subfamily Semisulcospirinae within Pleuroceridae was elevated to family level Semisulcospiridae by Strong & Köhler (2009).

Genera
Genera within the family Pleuroceridae are organized in the one subfamily only since 2009 and they include:

Pleurocerinae
 * Pleurocera Rafinesque, 1818 - type genus of the family Pleuroceridae,
 * Elimia H. Adams & A. Adams, 1854 synonyms:Goniobasis Lea, 1862
 * Athearnia Morrison, 1971
 * † Gyrotoma Shuttleworth, 1845
 * Io Lea, 1831 - with the only species Io fluvialis (Say, 1825)
 * Leptoxis Rafinesque, 1819
 * Lithasia Haldeman, 1840