Brachidontes pharaonis

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Brachidontes pharaonis
Brachidontes pharaonis

Brachidontes pharaonis

Systematics
Order : Mytiloida
Superfamily : Mytiloidea
Family : Blue mussels (Mytilidae)
Subfamily : Brachidontinae
Genre : Brachidontes
Type : Brachidontes pharaonis
Scientific name
Brachidontes pharaonis
( P. Fischer , 1870)

Brachidontes pharaonis is a shell - type from the family of mussels (Mytilidae). According to recent molecular biological studies was brachidontes pharaonis an endemic of the Red Sea and emigrated before 1876 (or was abducted with ships) as Lessepsscher migrants through the Suez Canal in the southeast Mediterranean one.

features

The evenly folded, moderately expanded housing is up to 40 mm long. It is oblong-wedge-shaped to slightly curved. Fischer gives the following dimensions (length to height to thickness) 35:16:13 mm. The highest point is roughly in the middle of the case. It is highly unequal and the vertebrae are at the front end or very close to the front end of the case. The outline and the ratio of length to height are somewhat variable. The dorsal margin rises with a slight curvature to the highest point and then merges with a slight curvature into the front edge. The ventral margin is concave, the ventral side relatively broad. The ligament is external, but deeply sunk in a longitudinal groove, with reinforcing shell ridges (nymphae or pseudonymphae), which extends from the vertebra to well over half of the rising dorsal edge (and below the highest point). The lock has some dysodontic teeth in front of and behind the ligament. The front and rear sphincters are of different sizes. The anterior sphincter sits on the ventral margin very close to the anterior end and is egg-shaped. It is not half the size of the posterior, egg-shaped sphincter. It sits in the rear part of the case, but clearly away from the rear end below the dorsal margin. There is no jacket bay.

The shell is quite firm. The ornamentation consists of numerous, strong ribs that repeatedly divide towards the rear end, which also become stronger towards the rear end. The spaces between the ribs show fine concentric stripes. The inner edge of the case is notched. The thick periostracum is black-brown, the inner surface is white with varying degrees of violet-black tint.

Similar Art

Brachidontes pharaonis can only be confused with the similar Septifer bilocularis in the area of ​​distribution . This species differs, however, by the septum under the vertebrae in the foremost part of the housing, and by the light green color (with reddish spots).

Geographical distribution, habitat and way of life

The original range of Brachidontes pharaonis is the Red Sea, so it was endemic there . According to the molecular biological investigations by Terranova et al. approved. Today it occurs as a Lessepsian migrant in large parts of the Mediterranean.

In 1876 the species was detected in Port Said , at the northern exit of the Suez Canal. Evidence followed in Lebanon in 1931, and off the Israeli coast in 1937 (at that time still Palestine ). It was detected in Sicily in 1971, in Greece in 1979 , and in Syria and southern Turkey in 1985 . In 1997 it was found for the first time in the Adriatic , both on the Italian and Croatian sides. By 2007 it had expanded into Sardinia and the French Mediterranean coast in the western Mediterranean . A further expansion of the distribution area cannot be ruled out.

The animals are typical inhabitants of the Felslitorals in the area of ​​the water level or only a few meters below, where they are attached with byssus threads to hard substrates or stones, larger shell fragments or coral fragments. They form colonies with a high density of individuals that can cover entire rocky coasts. The animals are suspension filter feeders that feed on phytoplankton and organic detritus in the water.

development

The animals are of separate sex. The sex products are released into the open water, where the eggs are fertilized. After hatching, a trochophora larva forms first , which transforms into a Veliger larva after about a day and drifts in the water for several weeks before it changes to metamorphosis and soil life.

Taxonomy

The taxon was established by Paul Fischer in 1870 as Mytilus pharaonis . The type locality is unfortunately not precisely named, but it can be safely assumed in the area of ​​the northern Red Sea ( Gulf of Suez , Gulf of Aqaba ). Until recently it was not always accepted as an independent species, but was instead included in the synonymy of Brachidontes variabilis Krauss, 1848. It is now accepted as a distinct species. This is supported by molecular biological work. The closest related species to Brachidontes pharaonis is Brachidontes variabilis . However, the (alleged) Pacific population of Brachidontes variabilis differed so clearly from that of the Indian Ocean that it can be artificially separated from it. Brachidontes pharaonis and Brachidontes variabilis (Indian Ocean) are more closely related than Brachidontes variabilis (Indian Ocean) and the (alleged) Brachidontes variabilis (Pacific Ocean).

Markus Huber put Brachidontes pharaonis in the synonymy of Brachidontes ustulatus (Lamarck, 1819). This species has its type-locality and its range in Western Australia. He also submitted that Mytilus variabilis Krauss, 1848 by Mytilus variabilis Fischer de Waldheim, was preoccupied in 1807. However, Cosel, Gofas and Poutiers made it clear in 2014 that the latter name is a forgotten name ( nomen oblitum ) and that it no longer needs to be renamed.

literature

  • Argyro Zenetos, Serge Gofas, Giovanni Russo, José Templado: CIESM Atlas of Exotic Species in the Mediterranean. Vol.3 Mollusca. CIESM (Frédéric Briand, ed.), Monaco, 2003 ISBN 92-990003-3-6 (p. 230/231, text online )

Individual evidence

  1. ↑ a b c Margherita Sirna Terranova, Sabrina Lo Brutto, Marco Arculeo, Jeffry B. Mitton: Population structure of Brachidontes pharaonis (P. Fisher, 1870) (Bivalvia, Mytilidae) in the Mediterranean Sea, and evolution of a novel mtDNA polymorphism. Marine Biology, 150: 89-101, 2006 doi : 10.1007 / s00227-006-0330-4
  2. ↑ a b c d Margherita Sirna Terranova, Sabrina Lo Brutto, Marco Arculeo, Jeffry B. Mitton: A mitochondrial phylogeography of Brachidontes variabilis (Bivalvia: Mytilidae) reveals three cryptic species. Journal of Zoological Systemat Evol Res 45 (4): 289-298, 2007 doi : 10.1111 / j.1439-0469.2007.00421.x
  3. ^ Paul: Fischer: Sur la faune conchyliologique marine des baies de Suez et de l'Akabah. Journal de Conchyliologie, 18: 161-179, Paris 1870 Online at www.biodiversitylibrary.org (p. 178)
  4. ↑ Peter Graham Oliver, Kevin Thomas (images): Bivalved seashells of the Red Sea. 330 pp., Wiesbaden, Hemmen et al. a., 1992 ISBN 3-925919-08-2 (p. 48 in Synonymy of Brachidontes variabilis )
  5. ↑ MolluscaBase: Brachidontes pharaonis (P. Fischer, 1870)
  6. ↑ Rudo von Cosel, Serge Gofas, JM Poutiers: Nomenclatural notes on some European and West African marine bivalve species. Iberus. 32 (1): 65-85, 2014