Tag Archives: Hemicycla

Hemicycla montefortiana Beck & Rähle

Monteforte Land Snail (Hemicycla montefortiana)

This species was described in 2006, its (sub)fossil shells were found in fossil beds in the Barranco de Monforte on the island of La Gomera, Canary Islands.

The shells reach sizes of about 4,6 cm in diameter, they are very similar to those of another extinct member of this genus, Mousson’s Land Snail (Hemicycla moussoniana (Wollaston)) but are larger. [1]

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The fossil beds of La Gomera have been dated to Late Pleistocene to Holocene age, thus the Monteforte Land Snail may very well have survived into the Holocene.

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References:

[1] T. Beck; W. Rähle: Description of a newly discovered extinct repreentative of the genus Hemicycla Swainson, 1840 (Gastropoda, Pulmonata, Helicidae) from La Gomera, Canary Islands. Basteria 70: 53-56. 2006

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edited: 05.12.2018

Hemicycla hedybia (Mabille)

Hedybia Land Snail (Hemicycla hedybia)

The Hedybia Land Snail was described in the year 1882, it is resp. was endemic to the Canary Islands, that is all that’s known, since the author (J. Mabille) did not mention any further data about the locality.  

The species may quite well still exist.

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Depiction from: ‘George W. Tryon; Henry A. Pilsbry; a.o.: Manual of Conchology. Second Series: Pulmonata Vol. 4, Helicidae Vol. 2. 1888’  

(public domain)

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edited: 17.10.2020

Hemicycla maugeana (Shuttleworth)

Valverde Land Snail (Hemicycla maugeana)

The quite variable Valverde Land Snail, described in 1852, was endemic to the island of El Hierro, Canary Islands, where it apparently was restricted exclusively to the lowland regions in the southern part of the island.

The species was not found during recent searches (around 2010) and may be extinct. 

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Depiction from: ‘George W. Tryon; Henry A. Pilsbry; a.o.: Manual of Conchology. Second Series: Pulmonata Vol. 4, Helicidae Vol. 2. 1888’  

(public domain)

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edited: 04.12.2018

Hemicycla gomerensis (Morelet)

La Gomera Land Snail (Hemicycla gomerensis)

This species was described in 1864, it is or was endemic the the island of La Gomera, Canary Islands.

The shell reaches a size of about 2,1 cm in diameter.

In proportion to its size the shell is extremely thin and fragile, being more than usually sub-diaphanous when held up to the light; and its colour is a deep castaneous-brwon, but rather paler (or more olivaceous) beneath, with extremely indistinct indications of three obsolete darker bands, – one of which is just below the dorsal line, another immediately above it, and the third a little behind the suture (the space between this last one and the suture being sometimes, apparently, though not in the specimens now before me, of a more lively ochreous yellow).” [1]

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The La Gomera Snail is listed in the Red List of the IUCN as ‘data deficient’, but may be already extinct.

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References:

[1] T. Vernon Wollaston: Testacea Atlantica: or the Land and Freshwater Shells of the Azores, Madeiras, Salvages, Canaries, Cape Verdes, and Saint Helena. London: L. Reeve & Co. 1878

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Depiction from: ‘George W. Tryon; Henry A. Pilsbry; a.o.: Manual of Conchology. Second Series: Pulmonata Vol. 4, Helicidae Vol. 2. 1888’

(public domain)

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edited: 05.12.2018

Hemicycla guanartemes (Grasset)

Guanarteme Land Snail (Hemicycla guanartemes)

This species was described in 1857, it is/was endemic to the island of Gran Canaria, Canary Islands.

The shell reaches/reached a size of about 2 cm in diameter.

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The Guanarteme Land Snail appears to have been quite common formerly.:

The present Helix was taken in Gran Canary both by Grasset and Fritsch, and subsequently in considerable abundance by Mr. Lowe and myself. We found it principally in and around the little town of Teror (on one occasion even within the house of Don Pedro Manrique), but likewise in the region of El Monte, – particularly in the hollows of old trees at the Laurealos, ….” [1]

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The species is listed (as Hemicycla guamartemes) in the Red List of the IUCN as ‘data deficient’, but, since it apparently was not found during recent searches, may be already extinct.

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References:

[1] T. Vernon Wollaston: Testacea Atlantica: or the Land and Freshwater Shells of the Azores, Madeiras, Salvages, Canaries, Cape Verdes, and Saint Helena. London: L. Reeve & Co. 1878

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Depiction from: ‘George W. Tryon; Henry A. Pilsbry; a.o.: Manual of Conchology. Second Series: Pulmonata Vol. 4, Helicidae Vol. 2. 1888’ 

(public domain)

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edited: 05.12.2018