Hystricella turricula

Hystricella turricula is a species of small, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae. This species is indigenous to the Madeira archipelago, where it only occurs on the islet Ilhéu de Cima.[1]

Hystricella turricula
Scientific classification
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Gastropoda
(unranked):
clade Heterobranchia
clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Stylommatophora
informal group Sigmurethra
Superfamily:
Helicoidea
Family:
Hygromiidae
Subfamily:
Geomitrinae
Tribe:
Geomitrini
Genus:
Hystricella
Species:
H. turricula
Binomial name
Hystricella turricula
(R. T. Lowe, 1831)
Synonyms
  • Discula turricula
  • Geomitra turricula Pilsbry, 1895
  • Ochthephila (Hystricella) turricula (Lowe, 1831)
  • Helix turricula R. T. Lowe, 1831
  • Helix (Hystricella) turricula Lowe, 1855
  • Helix (Hystricella) turricula var. pererosa Wollaston, 1878

Shell description

The shell of these snails is shaped like a discus, or a lens, with a sharp edge around the periphery of the whorls.[2] It may be easily distinguished, through external morphology, from all Hystricella and Wollastonia species from its "peculiarly turreted shell".[3]

Distribution and Ecology

Hystricella turricula is endemic to the coastal slopes and plateaus on the islet Ilhéu de Cima on the southeastern coast of Porto Santo. The species if found under volcanic rocks and debris scattered in open fields. The local form pererosa occurs on steep low-elevation slopes. Referenced collecting localities of De Mattia, Neiber & Groh, 2015 include: Quaternary slope deposits on the southwestern coast of Ilhéu de Cima, 33°03'15"N 16°17'02"W, 40 m; Ilhéu de Cima, top, under stones, 33°03'13"N 16°16'48"W, approx. 100 m.[3]

Conservation status

This species is mentioned in annex IV of the Habitats Directive. De Mattia, Neiber & Groh, 2015 consider this species to be Critically Endangered under criteria B1a,b(ii,v),2a,b(ii,v), as the species' extent of occurrence is less than 1 km2, and is imperiled by grazing and various unrecorded factors. Significant populational declines have been recorded, and the species is now restricted to one location on a high-altitude plateau.[3]

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References
  1. Seddon, M.B. (2011). "Hystricella turricula". IUCN Red List of Threatened Species. 2011: e.T6723A12800477. doi:10.2305/IUCN.UK.2011-1.RLTS.T6723A12800477.en.
  2. Hugh Watson (1923). "The anatomy and general affinities of Ochthephila (= Geomitra) turricula (Lowe)". Proceedings of the Malacological Society of London. 15 (6): 283–93.
  3. Mattia, Willy De; Neiber, Marco T.; Groh, Klaus (24 January 2018). "Revision of the genus-group Hystricella R. T. Lowe, 1855 from Porto Santo (Madeira Archipelago), with descriptions of new recent and fossil taxa (Gastropoda, Helicoidea, Geomitridae)". ZooKeys. 732: 1–125. doi:10.3897/zookeys.732.21677. ISSN 1313-2970.


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