Trona stercoraria
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Trona stercoraria |
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| Scientific name | ||||||||||||
| Trona stercoraria | ||||||||||||
| ( Linneus , 1758) |
Trona stercoraria is in Atlantic occurring sea snail and the only extant species of the genus Trona from the family of cowries . The two common international common names are “Rat Cowry” (rat cowry) and “Droppings Cowry” based on thename sterco rariagivenby Carl von Linné in 1758, which can be translated as excrement or dung. When Linnaeus named it, it was not decisive that the snail feeds on excrement or is in some other way connected with excrement, rather its appearance reminded him of dung. T. stercoraria probably has no subspecies.
description
The housing of this locally common type usually reach a size between 46 and 80 millimeters; the smallest documented find was 27, the largest 98.6 mm. The coat of T. stercoraria is thin, brown in color and has fine, closely spaced protuberances (papillae). The foot is voluminous. The color, pattern and shape of the cases vary widely. As a rule, the shell is thick-walled, spotted brown and oval to rhombic. The surface is smooth and shiny, but there are exceptions such as irregular patterns, melanism , overgrowths in the form of small bumps (caused by sticking barnacles ) and layers that cover the pattern of the shell ( "overcast" ) much more often than with other species of the family . Only the underside is unmistakable in almost all copies. Characteristic, clearly delimited light-colored teeth with dark brown spaces can be found on both sides of the aperture (the opening of the snail shell on the underside). The drawing ends at the transition from the back to the base, where it turns into a uniform light brown. The fossula is quite large and clearly concave.
Occurrence and habitat
The distribution area extends along the western African coast in Atlantic waters from Mauritania in the north to Luanda ( Angola ) in the south, the populated coastline is about 5000 km. The species is also found on the islands off the coast - such as the Cape Verde Islands or São Tomé and Príncipe .
Little is known about the way of life. Not least because of the often damaged shells, we know that they live in the intertidal zone on rocky ground.
Systematics
In 1758 Linnaeus described the species and assigned it to the genus Cypraea with all the cowries known to him at the time. In 1884, Félix Pierre Jousseaume established the genus Trona and moved Cypraea stercoraria to Trona stercoraria . Today both binomials are used, but Jousseaume's assignment is being used in more recent academic papers.
Trona stercoraria probably has no subspecies and, despite the strongly diverging individuals, only two forms are worth mentioning. On the one hand, there is the particularly small shape called minima and, on the other hand, a shape called rattus , which was described by Lamarck in 1810 . Although this form is considered a subspecies by some authors, the status is uncertain. T. stercoraria stercoraria f. rattus grows to 30 to 86 mm, is strongly arched and very broad.
The following names are used synonymously :
| atrata , Sullioti 1924 | gibba , Gmelin 1791 | nebulosa , Sullioti 1924 |
| cauteriata , Chemnitz 1888 | Gibber , Meuschen 1787 | nigrescens , Sullioti 1924 |
| cineracea , Sullioti 1924 | grummulus , Humphrey 1791 | olivacea , Sullioti 1924 |
| conspurcata , Gmelin 1791 | grummulus , Gray 1828 | tabulalusoria , Chemnitz 1788? |
| fasciata , Gmelin 1791 | ligata , Röding 1798 | tumulosa , Hidalgo 1906 |
| Gibba , Blainville 1826 | majet , Dautzenberg 1891 | viridis , Sullioti 1924 |
Web links
- Biological Library (BioLib): Trona stercoraria
- Hardy's Internet Guide to Marine Gastropods: Trona stercoraria stercoraria
- World Register of Marine Species: Trona stercoraria
literature
- Felix Lorenz & Alex Hubert: A Guide To Worldwide Cowries . 2000, ISBN 3-925919-25-2
- CM Burgess: The Living Cowries . 1970, ISBN 0498066770
- FA Schilder, M. Schilder: A catalog of living and fossil cowries . Memoirs Institut Royal Sciences Naturelle de Belgique, 1971.
Individual evidence
- ↑ EL Heiman: Diagnosting Cowry Species , Israel 2004, ISBN 965-90588-0-2 ; P. 99
- ↑ Donald L. Pisor: Registry Of World Record Size shells . 2008, ISBN 978-3-939767-12-1 ; P. 73
- ↑ Hardy's Internet Guide to Marine Gastropods: Trona stercoraria stercoraria rattus (f)