Hemicycla (Hemicycla saulcyi)

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Hemicycla saulcyi
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Hemicycla fact file

Hemicycla description

KingdomAnimalia
PhylumMollusca
ClassGastropoda
OrderStylommatophora
FamilyHelicidae
GenusHemicycla (1)

Rediscovered as recently as 1992, some 150 years after it was first described (3), Hemicycla saulcyi is a medium-sized snail with a dark blue-grey body and a rather attractively marked shell, which is brown with long, irregular white lines that generally run at an angle to the axis of the shell. The shell is more or less spherical, although slightly conical, and the edge of the shell opening (peristome) extends into a well-developed lip (2) (3). Only one subspecies of this snail remains, Hemicycla saulcyi saulcyi; a second, Hemicycla saulcyi carta, is now extinct, and has only been found as fossils (2) (3) (4) (5). H. s. carta differed from H. s. saulcyi mainly in its more solid, wider shell, which had a thicker and wider lip (3).

Size
Length: 24 - 28 mm (2)
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Hemicycla biology

There is no information currently available on the biology or life history of Hemicycla saulcyi, and only around thirty living specimens have been observed to date (2) (6).

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Hemicycla range

Hemicycla saulcyi is endemic to Gran Canaria, in the Canary Islands (Spain) (1) (2) (6) (7). The remaining population occupies an area of less than four square kilometres, in La Isleta, just to the north of the capital, Las Palmas de Gran Canaria (2) (3) (4) (5). Fossils of H. s. carta have also been found in the north of the island, between Agaete and La Isleta (2) (3) (4).

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Hemicycla habitat

This species inhabits a relatively arid area of sparse vegetation and lichen cover on stony-clay soil, at elevations between 120 and 238 metres, with most individuals having been found on north-facing slopes that receive moist sea air. Vegetation in the area includes the spurge Euphorbia aphylla, and shrubs such as Lycium intricatum and Suaeda vera (2) (3) (6).

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Hemicycla status

Classified as Critically Endangered (CR) on the IUCN Red List (1).

IUCN Red List species status – Critically Endangered

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Hemicycla threats

The natural ecosystems of Gran Canaria are highly deteriorated, a situation which has had negative impacts on a variety of endemic species (4). Habitat loss has drastically reduced the range of Hemicycla saulcyi, and the species is now restricted to a small, isolated population occupying a total area of under four square kilometres (2) (4) (5) (6). Most of La Isleta is an old military base, which has so far prevented encroachment by the city of Las Palmas de Gran Canaria. However, this base is being closed, and the likely increase in building and development in the area could be disastrous for this species (2) (5) (7). A further potential threat may come from the spread of introduced snails, which are believed to compete with the endemic snail species, potentially displacing them from some areas (4). Predation by rats, mice and lizards may also be a problem (3).

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Hemicycla conservation

No species of land snail in the Canary Islands currently receives direct legal protection, and therefore indirect protection through preservation of its habitat will be all the more vital to both Hemicycla saulcyi and other threatened endemic snails (2) (4) (7). It has been recommended that the north-western part of La Isleta be made a Special Nature Reserve, in order to prevent building and development in the area. A Recovery Plan has also been recommended to promote the restoration of the natural vegetation (2) (4). With only around thirty living specimens of Hemicycla saulcyi saulcyi observed to date, the total population may be tiny (2) (6), and, without adequate protection, the future for this highly endangered mollusc is uncertain.

View information on this species at the UNEP World Conservation Monitoring Centre.
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Find out more

To find out more about Hemicycla saulcyi and other threatened wildlife in the Canary Islands, see:

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Authentication

Authenticated (17/05/10) by Miguel Ibañez, Species Expert, Canarian land snails. Department of Animal Biology, University of La Laguna, Tenerife.

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Glossary

Endemic
A species or taxonomic group that is only found in one particular country or geographic area.
Lichen
A composite organism made up of a fungus in a co-operative partnership with an alga. Owing to this partnership, lichens can thrive in harsh environments such as mountaintops and polar regions. Characteristically forms a crustlike or branching growth on rocks or tree trunks.
Molluscs
A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
Subspecies
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
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References

  1. IUCN Red List (April, 2010)
    http://www.iucnredlist.org/
  2. Ibáñez, M. and Alonso, M.R. (2009) Hemicycla saulcyi saulcyi (d’Orbigny, 1839). In: Verdú, J.R. and Galante, E. (Eds.) Atlas de los Invertebrados Amenazados de España (Especiés En Peligro Crítico y En Peligro). Dirección General para la Biodiversidad, Ministerio de Medio Ambiente, Madrid. Available at:
    http://www.mma.es/portal/secciones/biodiversidad/inventarios/inb/atlas_inverte_amenazados/pdf/hemicycla_saulcyi.pdf
  3. Groh, K., Alonso, M.R., Ibañez, M. and Henriquez, F.C. (1992) Rediscovery of Hemicycla saulcyi (d’Orbigny, 1839), a revision of its fossil allies (Gastropoda: Helicidae), and description of a new species of Napaeus (Enidae), both from La Isleta, Gran Canaria, Canary Islands. Schriften zur Malakozoologie, 5: 1-12.
  4. Ibáñez, M., Alonso, M.R., Henríquez, F. and Valido, M.J. (1997) Distribution of land snails (Mollusca, Gastropoda, Pulmonata) on the island of Gran Canaria (Canary Islands) in relation to protected natural areas. Biodiversity and Conservation, 6: 627-632.
  5. Ibáñez, M. (2010) Pers. comm.
  6. de Abreu, S.M. (2009) Hemicycla saulcyi saulcyi. In: Evaluación de Especies Catalogadas de Canarias. Gobierno de Canarias, Las Palmas de Gran Canaria. Available at:
    http://www.gobiernodecanarias.org/cmayot/medioambiente/medionatural/biodiversidad/especies/catalogodeespeciesamenazadas/index.html
  7. Ibáñez, M. and Alonso, M.R. (2005) Hemicycla saulcyi saulcyi (D’Orbigny, 1839). In: Verdú, J.R. and Galante, E. (Eds.) Libro Rojo de los Invertebrados de España. Dirección General de Conservación de la Naturaleza, Madrid. Available at:
    http://carn.ua.es/CIBIO/en/lrie/lrie.html
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Image credit

Hemicycla saulcyi  
Hemicycla saulcyi

© Miguel Ibañez

Miguel Ibanez
miban.ull@gmail.com

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