Austronucula perminima
| Austronucula perminima | ||||||||||||
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| Scientific name | ||||||||||||
| Austronucula perminima | ||||||||||||
| ( Monterosato , 1875) |
Austronucula perminima is a type of mussel from the nut shell family(Nuculidae). It is a very small type of nut shell that is native to the shallow water of the Mediterranean.
features
The bilateral, inflated housing is approximately trapezoidal-ovoid in outline; the maximum length is up to 1.1 millimeters. It is longer than it is tall, about four-fifths of its length in height. The case is unevenly hinged, the vertebra is behind the center (at about a third of the rear end). The anterior dorsal margin is curved, at first a little, then sloping abruptly to the anterior margin. The posterior dorsal margin first gradually falls away from the vertebra and is then truncated. The ventral margin is broadly rounded. The protoconch is rounded, measures about 200 µm in diameter and has a spical indentation. The surface is rough and has small indentations with the exception of the edge, which is almost smooth. The Teleoconch shows fine concentric growth lines and fine radial lines. The radial lines are thin, diverging slightly towards the front and rear, and are closer together than the concentric growth strips. The lock or lock line is bent at an angle (approx. 90 °) and is therefore divided into a slightly longer front and a slightly shorter rear part, which contain both primary and secondary teeth. The primary teeth are narrow and take up approximately half of the lock plate. There are 5 teeth in front of and behind the chondrophor. The secondary teeth are wide and bump-like. There are 3 to 4 teeth in front of and 2 to 3 teeth behind a chondrophor . A chondrophor is a protruding cupped process on which the ligament is attached. The chondrophore lies under the narrowest area of the lock plate. It is broad, and more or less symmetrical, the lower edge is rounded. The anterior and posterior, egg-shaped sphincter muscles are approximately the same size, but hardly pronounced. The jacket line is only weakly pronounced and has no jacket bay. The inner ventral margin is smooth. The periostracum is light greenish-brown.
Similar species
The species is reminiscent of the juvenile forms of other types of nut clams living near the coast, especially Nucula hanleyi , which occurs sympatric with Austronucula perminima . This species differs mainly in its adult size (up to 18 mm). In the case of Nucula hanleyi, there are also no primary teeth formed in this way in the size stage around 1 mm. The radial lines on the early part of the teleoconch in Austronucula perminima are much denser than in other European nuculids. The roughly trapezoidal outline of the housing is also characteristic. Condylonucula bicornis is very similar in adult size and lock , but differs in its housing outline and protoconch.
Geographical distribution and habitat
The species is known from Sicily , the French Mediterranean coast and the Alborán Island in the western Mediterranean. It lives there between algae on hard soils near the coast at depths of 5 to 40 m.
In 2013 Thanasis Manousis and Sofia Galinou-Mitsoudi found a small nut shell in the Aegean Sea (Greece), which they called Nucula sp. which, however, coincides with Austronucula perminima in most of its characteristics .
Taxonomy
The taxon was established in 1875 by Tommaso di Maria Allery Monterosato as Nucula perminima . The species is assigned to the genus Austronucula Powell, 1939 by MolluscaBase . The species was described again by Godas and Salas under the name Nucula recondita ; this name is thus a more recent synonym of Austronucula perminima (Monterosato, 1875). The holotype of Austronucula perminima is said to be kept in the Museo Civico di Zoologia di Roma in Rome (Italy). The holotype and 3 paratypes of Nucula recondita are in the Museo Nacional de Ciencias Naturales in Madrid (Spain). Other paratypes are kept in the Muséum national d'histoire naturelle in Paris (France).
literature
- Serge Gofas, Carmen Salas: Small Nuculidae (Bivalvia) with functional primary hinge in the adults. Journal of Conchology 35 (5): 427-435, 1996 ResearchGate
Individual evidence
- ↑ www.micromolluschimediterranei.it: Austronucula perminima (Monterosato, 1875) (pictures)
- ↑ Thanasis Manousis, Sofia Galinou-Mitsoudi: New and uncommon Bivalvia Mollusca of Thermaikos Gulf (NW Aegean Sea). Journal of Biological Research-Thessaloniki 20: 339-366, 2013 PDF
- ↑ Tommaso di Maria Allery Monterosato: Poche note sulla Conchiologia Mediterranea. 15 p., Palermo, Tipografia del Giornale di Sicilia, 1875. (not seen)
- ↑ MolluscaBase: Austronucula perminima (Monterosato, 1875)