Pachychilidae

Pachychilidae, common name pachychilids, is a taxonomic family of freshwater snails, gastropod molluscs in the clade Sorbeoconcha.

Distribution
Pachychilids are freshwater snails with a worldwide distribution in the tropics. Representatives are found in South and Central America, Africa, Madagascar, South and South-east Asia and tropical Australia (Queensland: Torres Strait Islands).

Description
Pachychilids have an operculum, which is concentric and multispiral.

Ecology
All species in the family inhabit freshwater except Faunus ater, which is a brackish water snail found in estuaries and other coastal habitats. Pachychilids are either oviparous (lay eggs), ovoviviparous or viviparous (retain developing eggs and youngs in special incubatory structures).

Notes on the taxonomy
The name is derived from a combination of the words 'pachy' (Greek = thick) and the suffix '-chilus' (Greek = Lip), meaning 'thick lipped' - with respect to the thickened aperture of the shell in some species. Most 20th-century authors did not recognize Pachychilidae as an independent family, but affiliated species under different groups, such as Thiaridae and Pleuroceridae. However, recent revisions based on molecular and morphological evidence have proven their independent and distinct status from the former. This family has no subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).

Genera
Genera within the family Pachychilidae include:
 * † Bellatara Strand, 1928 - with only one species Bellatara janus (Mayer, 1870)
 * Brotia H. Adams, 1866
 * Doryssa Swainson, 1840
 * † Eginea Pacaud & Harzhauser, 2012
 * Faunus de Montfort, 1810 with the only species Faunus ater (Linnaeus, 1758)
 * Jagora Köhler & Glaubrecht, 2003
 * † Jponsia Pacaud & Harzhauser, 2012
 * Madagasikara Köhler & Glaubrecht, 2010 - synonym: Melanatria Bowdich, 1822 auctt.
 * † Nodifaunus Olsson, 1944
 * Pachychilus I. Lea & H. C. Lea, 1851 - type genus of the family Pachychilidae
 * Paracrostoma Cossmann, 1900
 * Potadoma Swainson, 1840
 * † Pseudobellardia Cox, 1931
 * Pseudopotamis Martens, 1894
 * Sulcospira Troschel, 1858 - synonym: Adamietta Brandt, 1974
 * † Tinnyea Hantken, 1887
 * Tylomelania Sarasin & Sarasin, 1897
 * † Wingeastonia K. Martin, 1906
 * Genera brought into synonymy:
 * Acrostoma Brot, 1871: synonym of Paracrostoma Cossmann, 1900
 * Antimelania P. Fischer & Crosse, 1892: synonym of Brotia H. Adams, 1866
 * Brotella Rovereto, 1899: synonym of Paracrostoma Cossmann, 1900
 * Fauninae Cossmann, 1909 (subfamily) : synonym of Pachychilidae P. Fischer & Crosse, 1892
 * Melanatria Bowdich, 1822: synonym of Faunus Montfort, 1810
 * Oxymelania Crosse & P. Fischer, 1892: synonym of Pachychilus I. Lea & H. C. Lea, 1851
 * Pirena Lamarck, 1822: synonym of Faunus Montfort, 1810
 * Sphaeromelania Rovereto, 1899: synonym of Pachychilus I. Lea & H. C. Lea, 1851
 * Wanga Chen, 1943: synonym of Brotia H. Adams, 1866

Cladogram
A cladogram based on sequences of mitochondrial 16S ribosomal RNA sequences showing phylogenic relations of Pachychilidae: