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Radix Montfort, 1810

Diagnostic features

Small to large, oval to ear-shaped freshwater lymnaeid snails with a large aperture. The animal has large triangular tentacles.

Species of Radix have shells sculptured with fine axial lamellae and the prostate has a single large fold. Many species with a solid black band parallel to the mantle collar and there is a uterine appendix.  Species of Radix have 17 pairs of chromosomes, compared with 16 pairs in Austropeplea and Bullastra and 18 pairs in Lymnaea and Pseudosuccinea.

Classification

Class Gastropoda

Subclass Heterobranchia

Order Hygrophila

Superfamily Lymnoidea

Family Lymnaeidae

Subfamily: Amphipepleinae

Genus Radix Montfort, 1810

Type species: Radix auriculatus Montfort, 1810.

Original reference: Montfort D. de (1810). Conchyliologie systématique, et classification méthodique des coquilles; offrant leurs figures, leur arrangement générique, leurs descriptions caractéristiques, leurs noms; ainsi que leur synonymie en plusieurs langues. Ouvrage destiné à faciliter l'étude des coquilles, ainsi que leur disposition dans les cabinets d'histoire naturelle. Coquilles univalves, non cloisonnées. Tome second. pp. [1-3], 1-676. Paris: Schoell.

Type locality: Europe.

Synonyms: Gulnaria Leach in Turton, 1831; Neritostoma Klein in H. & A. Adams, 1855; Auriculariana Servain, 1881.

We treat three species assigned to Radix in this resource but there are others that may be introduced and some have been intercepted by Australian Biosecurity officials. These include the species illustrated below.

State of taxonomy

Lymnaeid taxonomy is in urgent need of a comprehensive review.

Biology and ecology

On submerged water plants in ponds, swamps and poorly drained pasture, and along edges of streams, commonly on damp mud above water line. Biology similar to other lymnaeids. Feeds on algae and detritus. Egg mass a crescent-shaped jelly strip containing many small eggs. Development direct.

Distribution

Species are found in Eurasia, North America, north Africa, South America, India and Asia, including Indonesia.

Introduced to many other parts of the world.

Notes

Like Austropeplea, this genus is a host of liver fluke (Fasciola hepatica), a parasite that infects livestock and sometimes humans. The genus is also known to host many parasites in Europe and Asia, including Fasciola gigantica, a parasite of cattle and sheep.

We treat three species of Radix individually but three additional species are illustrated here that are sometimes intercepted by Australian Biosecurity.

Further reading

Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.

Boray, J. C. (1978). The potential impact of exotic Lymnaea spp. on fascioliasis in Australasia. Veterinary Parasitology 4: 127-141. 

Correa, A. C., Escobar, J. S., Durand, P., Renaud, F., David, P., Jarne, P., Pointier, J.-P. & Hurtrez-Boussès, S. (2010). Bridging gaps in the molecular phylogeny of the Lymnaeidae (Gastropoda: Pulmonata), vectors of Fascioliasis. BMC Evolutionary Biology 10 381(1-12)..

Hubendick, B. (1951). Recent Lymnaeidae: their variation, morphology, taxonomy, nomenclature and distribution. Kongliga Svenska Vetenskapsakademiens Handlingar 3: 1-223.

Kershaw, R. C. (1975). Tasmanian aquatic non-marine Mollusca. Part 1. Lymnaea. Tasmanian Naturalist 40: 1-4.

Kershaw, R. C. (1991). Snail and Slug Pests of Tasmania, Queen Victoria Museum and Art Gallery.

Ng, T.H., Tan, S.K., Wong, W.H., Meier, R., Chan, S-Y., Tan, H.H. and Yeo, D.C.J. 2016. Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade. PLOS One. DOI:10.1371/journal.pone.0161130.

Pfenninger, M, Cordellier, M. & Streit, B. (2006). Comparing the efficacy of morphologic and DNA-based taxonomy in the freshwater gastropod genus Radix (Basommatophora, Pulmonata).BMC Evolutionary Biology 6: 100 (1-14).

Remigio, E. (2002). Molecular phylogenetic relationships in the aquatic snail genus Lymnaea, the intermediate host of the causative agent of fascioliasis: insights from broader taxon sampling.Parasitology Research 88: 687-696.Smith, B. J. & Kershaw, R. C. (1979). Field guide to the non-marine Molluscs of South-eastern Australia. Canberra, A.N.U. Press.

Smith, B. J. & Kershaw, R. C. (1981). Tasmanian Land and Freshwater Molluscs. Hobart, University of Tasmania.