Thyrophorella thomensis
| Thyrophorella thomensis | ||||||||||||
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Thyrophorella thomensis |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Thyrophorellidae | ||||||||||||
| Girard , 1895 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Thyrophorella | ||||||||||||
| Greeff , 1882 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Thyrophorella thomensis | ||||||||||||
| Greeff , 1882 |
Thyrophorella thomensis is a species from the suborder of land snails (Stylommatophora). It is the only species in the genus Thyrophorella , which in turn is the only genus in the Thyrophorellidae family . The species is endemic to the island of São Tomé .
features
The case is left-handed and low-tapered. They reach 9 mm in diameter and 4 mm in height. At first they have a weakly pronounced lateral shoulder, which becomes a sharp edge on the end turn. The turns are strongly arched at the bottom; especially the end turn increases very strongly in thickness at the bottom. In total, only about three turns are formed.
The shell is relatively thin and translucent. The color varies from yellowish to horn-colored. The embryonic convolutions are provided with weak, radial folds, which merge into fine, irregularly curved radial striae on the following convolutions. The mouth is semicircular and is almost perpendicular to the coil axis. The mouth edges are simple and sharply pointed. The upper edge is straight and the lower edge is semicircular. The opening can be closed with a kind of operculum . However, it is not homologous with the operculum of other groups of snails , but is an extension of the upper part of the peristome . It is connected to this by a flexible zone consisting of periostracum . This secondary mechanism to close the housing is unique within the screw. Housing growth appears to be in spurts. The operculum is only formed in phases in which the casing does not grow much. In phases of strong growth, it is calcified, integrated into the growing housing and the animal does not have a lid for a short time. The cover cannot be moved by muscle power, but falls when the animal is withdrawn into the housing or is pushed open when the animal comes out of the housing again. The navel is wide and open.
In the male part of the sexual apparatus, the penis is relatively long with a pulling muscle attached to the end of the penis. In the female part, the vagina is very distended and the atrium is very narrow. The stem of the sperm library is very short.
Geographical distribution, occurrence and way of life
The species occurs only on the island of São Tomé in the Gulf of Guinea in the South Atlantic. Since the last more detailed description in 1895, evidence of this species was not found again until 1993, when a living animal could be photographed. Little is known about the way of life. The specimens found in 1882 were found at Monte Café at an altitude of around 800–900 m, those from 1895 at an altitude of around 1000 m.
swell
Individual evidence
- ^ A b Edmund Gittenberger: Adaptations of the aperture in terrestrial gastropod-pulmonate shells. Netherlands Journal of Zoology, 46 (3-4): 191-205, 1996 doi : 10.1163 / 156854295X00159
- ^ A b Albert Alexandre Girard: Sur le "Throphorella thomensis", Greeff. Gastéropode terrestre muni d'un faux opercule á charnière . Journal de sciencias mathematicas, physicas e naturaes, 4: 28–31, 1897 Google Book Search (US)
- ^ Richard Greeff: About the land snail fauna of the island of São Thomé . Zoologischer Anzeiger, 5 (101–128): 516–521, 1882 Google Book Search (US)
literature
- Anatolij A. Schileyko: Treatise on Recent terrestrial pulmonate molluscs. Part 7: Endodontidae, Thyrophorellidae, Charopidae. Ruthenica, Supplement, 2 (7): 881-1034, Moscow 2001 ISSN 0136-0027
Web links
- Image of Thyrophorella thomensis
- Thyrophorella thomensis inthe IUCN 2013 Red List of Threatened Species . Listed by: Gasgoigne, A, 1996. Retrieved September 16, 2013.