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Helisoma duryi (Wetherby, 1879)
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Species name:
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Helisoma duryi (Wetherby, 1879)
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Taxon name:
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Planorbis (Helisoma) duryi Wetherby, 1879
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Originally described in:
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Wetherby, A. G. 1879. Notes on some new or little known North American Limnæidæ. - Journal of the Cincinnati Society of Natural History 2 (2): 93-100.
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Distribution:
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Originally from S USA (Florida), introduced to South Africa, E Africa, Peru, Brazil, Hawaii, in Europe reported from isolated spots in various countries
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Diagnosis:
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Shell light orange or yellowish, smaller than Planorbarius corneus, lower side flat with blunt edge at the peripery, upper side with deep umbilicus, 4-4.5 whorls, last whorl not too much inflated, apertural margin not reflected.
Animal with pigment spots.
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Size:
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Up to 10 x 25 mm
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Biology:
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Snails feed on desintegrating plants, detritus, dead aquaria animals, algae, fish food and vegetables. Animals can survive short periods of drought, they withdraw deeply inside the shell.
In Europe restricted to artificially warmed waters, in temperate zones there are probably no permanent populations. In Sicily restricted to small artificial ponds and fountains. One population in Austria was established in the 1980s, but has ceased to exist before 2002.
The species is sold for aquaria in Europe.
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Threatened:
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Family:
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Planorbidae
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Higher group:
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Gastropoda
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Comments:
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References: Wetherby 1879, Falkner 1990: 132, Falkner et al. 2001: 28, Glöer 2002: 247 ("Rheinland"), Falkner et al. 2002: 98 (Corse), Alexandrowicz 2003 (Lago Albano (Italy), Austria at Baden and Villach), Beckmann 2007: 49 (Mallorca), Reitano et al. 2007: 313 (Sicily), www.faunaeur.org (1/2007), De Oliveira 2010 (Coimbra), Welter-Schultes 2012: 66 (range map Europe).
12.2011: Google Scholar had 793 hits for Helisoma duryi, 120 hits for Planorbella duryi.
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