''Theodoxus valentinus'' is a species of freshwater gastropod in the nerite family, native to natural

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

channels in

Valencia, Spain Valencia ( va, València) is the capital of the autonomous community of Valencia and the third-most populated municipality in Spain, with 791,413 inhabitants. It is also the capital of the province of the same name. The wider urban area also ...

. This species was believed extinct, but has recently been rediscovered to persist in small populations in three different sites.

Description

''T. valentinus'' has a globose shell with four whorls, the last of which occupies much of the shell, and well-developed columnar callosity. The deep groove of the largest whorl and the wavy form of its aperture distinguish it from other Spanish '' Theodoxus''. The shell is highly variable in color, though mostly ranging from deep purple to bright red, with striped and solidly-decorated forms.ALBERTO MARTÍNEZ-ORTÍ, FERNANDO ROBLES, BENJAMÍN GÓMEZ, PAUL BUNJE Y ANA Mª PUJANTE. ''Theodoxus valentinus''.

Ecology and threats

''T. valentinus'' requires highly oxygenated water with a high calcium content of a temperature ranging between 16-18ºC; this specialization makes this species highly susceptible to water pollution and changes in environmental conditions such as drought and water extraction. Its susceptibility to habitat loss has paired with damage from

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

. The species was highly abundant in the original sites until the 1980s, when the species faced significant declines which have not slowed. The species is now only known from three sites along a 10 x 2 km stretch of the Rio Verdu, extirpated from its original Los Santos River habitat. This species is listed as Critically Endangered on the IUCN Red List. ''T. valentinus'' lays many oval-shaped eggs 0.8-1 mm in diameter on hard substrates (those on which it feeds) of which only one hatches. Reproduction occurs throughout the year. ''T. valentinus'' is predated actively upon by ostracods. Longevity among ''T. valentinus'' ranges from 17.8-22 months.

References

{{Taxonbar, from=Q14752158 Neritidae