Distribution patterns of the genus <i>Paludomus</i> (Gastropoda: Thiaridae: Paludominae) in Mahaweli, Kelani, Kalu, Gin and Maha-Oya river basins of Sri Lanka

Abstract

Since the publication of Preston's Fauna of British India-Freshwater Gastropoda and Pelcypoda in 1915, a vast amount of knowledge has accumulated on the fresh water molluscs. Starmühlner (1974) published a monograph on the fresh water gastropods, in which he listed 31 species of freshwater snails from Sri Lanka. Until the early 20th century, malacologists used mainly conchological characters to describe species. However, the shells of freshwater gastropods are highly variable, show ecological plasticity, and are known to suffer from convergence and homoplasy, and therefore do not always reliably reflect systematic boundaries. It is already known that other groups of freshwater organisms in Sri Lanka including fish and crabs show high levels of endemism within individual river basins. It remains to be discovered whether molluscs too, show such basin-level endemism. These studies also found that there was significant altitudinal stratification and basin-level endemism of species, a factor that remains to be assessed for aquatic molluscs. In order to address these questions, and assess the diversity of this fauna, we surveyed the freshwater mollusc fauna (focusing mainly on the genus Paludomus) in the Mahaweli, Kelani, Kalu, Gin and Maha-Oya River basins of Sri Lanka. A total of 10 morphospecies were recorded, based on examination of 20 specimens of each species from 20 locations in the altitude range 100-2000 m above mean sea level. Species-level identification is in progress, and further surveys are needed to assess the full diversity of this important fauna.

Annotated nomenclator of extant and fossil taxa of the Paludomidae (Caenogastropoda, Cerithioidea)

“…33.5.1), as the reference to Chemnitz (1786: 175) suggests that Gmelin was aware of the correct etymology of the species epithet. The name Helixlanschaurica has rarely been used as the valid name of a taxon (Rees 1819; Woodarch 1820; Wodarch and Mawe 1822, 1825, 1827, 1831, 1833; Bosc 1802, 1824, 1836; Pfeiffer 1840, 1841) and to our knowledge only once after 1900 (Coan and Petit 2011), whereas Helixtanschaurica is comparatively frequently used (e.g., Gmelin 1792; Frauenfeld 1864 as Helixtanschaurica ; Schmidt 1818 as Melaniatanschaurica ; Gray 1855 as Paludinatanschaurica ; Hanley and Theobald 1876; Preston 1915b; Seshaiya, 1929, 1934; Jacob 1959; Satyamurty 1960; Starobogatov 1970; Subba Rao and Mitra 1979; Brown 1980, 1994; Fretter 1984; Brown and Mandahl-Barth 1989; Daniel et al 1998; Dillon 2000; Strong and Glaubrecht 2002; Thasun Amarasinghe and Krishnarajah 2009; Strong et al 2011 as Paludomustanschaurica ; Starmühlner 1974, 1977, 1979; Subba Rao 1989 as Paludomustanschauricus ) and usually attributed to Gmelin (1791) (although sometimes with a wrong date). Paludomussanschauricus as used by Adams and Adams (1853–1854) is an incorrect subsequent spelling.…”