Alabes dorsalis

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Alabes dorsalis
Alabes dorsalis

Alabes dorsalis

Systematics
Perch relatives (Percomorphaceae)
Ovalentaria
Order : Gobiesociformes
Family : Tortoiseshell fish (Gobiesocidae)
Genre : Alabes
Type : Alabes dorsalis
Scientific name
Alabes dorsalis
( Richardson , 1845)

Alabes dorsalis , called “shore eel” in its South Australian homeland, is a small fish from the family of tortoiseshells (Gobiesocidae).

description

The color of the approx. 12 cm long alabes dorsalis is grass to olive green, brown or yellow-red (fixed animals in the museum mostly red), often with some large round dark spots on the sides. The body is almost round, at least ten times as long as it is high; the unpaired fins are connected to a low rim, but rays exist only in the caudal fin area (C 7-8), which tapers to a point. The pectoral fins have disappeared. The eyes are quite large, the muzzle is short and blunt. The jaw teeth are strong (one row of pointed teeth).

In the dorsal artery , the abdominal suction cup is still recognizable (V 3), in the other eight species it is completely reduced. The gill openings are shifted ventrally , fused and surrounded as a transverse gap by a small bulge (the "lips"). This creates a great external resemblance to the freshwater Synbranchidae . The premaxillary has a very long ascending process (although the mouth cannot be extended - hence no rostral cartilage); a submaxillary cartilage is present. The palatine is quite reduced and has no contact with the rest of the jockstrap. The hyomandibular is directed at the front only on the sphenoticum (otherwise in fish mostly also on the prooticum). The interhyal does not steer inside the hyomandibular (-end) e as usual, but rather on the outside. Only three Branchiostegal radii. Gills only on three gill arches. Side lines of the head incomplete, in particular the preoperculo-mandibular canal is missing. The front narine is briefly extended like a tentacle. 66-78 vertebrae, 22 of which are precaudal vertebrae (vertebrae in front of the caudal spine).

Distribution, habitat and way of life

The "beach eel" occurs only on the south coast of Australia , including most of the east coast of New South Wales , and the northeast coast of Tasmania . Its habitat are the intertidal (tidal zone) and flat subtidal zones of reef and seagrass areas. It can also be found in tidal pools , where it can lie in hiding for hours without an influx of fresh water. It often lives hidden under stones and shells and in seaweed or algae lawns to a depth of about 10 m, but is more often discovered than other beach eels due to its size. The diet consists of invertebrates, especially crustaceans . The species (like its relatives) is not of economic importance. In Tasmania, 250 specimens may be caught annually for the aquarium industry.

Systematics

The Alabes species are grouped together in the subfamily Cheilobranchinae, which is endemic to Australia . Alabes is the only genus in Cheilobranchinae. Without a suction cup, the close relationship to the Gobiesocidae was unclear for a long time, so that the fish were isolated as Cheilobranchidae or as "Alabetidae" (which is grammatically incorrect again - only Alabidae would be correct); V. Springer (1976) even rejects a separate subfamily because it is not characterized by a positive attribute. The clearest indication of the close relationship is the ball joint between the Supracleithrum and Cleithrum in the shoulder girdle. According to Springer, Alabes appears to be most closely related to gastrocymbe .

literature

  • Victor Gruschka Springer and Thomas H. Fraser (1976): Synonymy of the fish families Cheilobranchidae (= Alabetidae) and Gobiesocidae, with descriptions of two new species of Alabes. - Smithsonian Contributions to Zoology 234. 27 pp. ( Online ; PDF; 12.5 MB)
  • Barry Hutchins (2006): Description of two new species of shore-eels (Gobiesocidae: Cheilobranchinae: Alabes) from south-eastern Australia and Norfolk Island. In: Memoirs of Museum Victoria 63 (1): 25–28. (Differentiation of the species, online ; PDF; 248 kB).

References and footnotes

  1. ↑ Alabes dorsalis on Fishbase.org (English)
  2. ↑ a b Barry Hutchins, Sue Morrison: Five New Fish Species of the Genus Alabes (Gobiesocidae: Cheilobranchinae). In: Records of the Australian Museum (2004) Vol. 56: 147-158. ISSN  0067-1975 ( Online ; PDF; 206 kB)
  3. ↑ JL Baker: Gobiesocidae. Chapter in: Baker, JL (2012) Marine Species of Conservation Concern in South Australia: Volume 1 - Bony and Cartilaginous Fishes. 2009, p. 4. ( Online ( Memento from May 12, 2013 in the Internet Archive ))
  4. ↑ The name of a subfamily does not have to be changed, even if the genus that gave it its name has been renamed.

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