Tonga Escolar
| Tonga Escolar | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Tongaichthys | ||||||||||||
| Nakamura & Fujii, 1983 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Tongaichthys robustus | ||||||||||||
| Nakamura & Fujii , 1983 |
The Tonga Escolar ( Tongaichthys robustus ) is a fish from the family of the mackerel (Gempylidae) that was first discovered and described in 1983 . As far as we know so far, it occurs only in a very limited marine area and is also conspicuous in that its body proportions resemble a sexually mature form of youth - earlier this could have been classified as neoteny . However, as the fin formula shows, it is by no means a neotene form of a known genus. Like the common Escolar and quite different from other genera of the Gempylidae family, this fish approximates the mackerel and tuna ("torpedo") shape (it is called semifusiform: fusus "spindle"). This genus is also monotypical .
features
The body is slightly compressed, the head takes up just under 1/3 of the total length (approx. 30 cm) - the mouth and eyes are therefore large, the muzzle quite blunt. The front of the upper jaw is covered with (small) fangs (1–3), otherwise (like the lower jaw) with a number of smaller, flat dog teeth (in the upper jaw approx. 40, in the lower jaw less dense, approx. 10, but larger, especially in the middle of the row), the vomer with about 13, the palatine with about 30 small teeth. The spines of the gill trap are complex (finely toothed). The pseudo branch is well developed.
Fin formula : D1 XV – XVI (delicate spines, not very high), D2 I / 14–17, AI (delicate) / 14–16; both followed by 5 to 6 flakes. P (short, low angle) I (tender) / 16–18, VI / 5 (short). Tail root with indistinct keel on both sides.
The sideline runs from the upper end of the gill cover column arched to the C. Scales of the “cheek” enlarged. 33 vertebrae (of which 18 are pre-caudally, i.e. in the trunk, on the body cavity) - Back dark brown, otherwise partly lighter, partly (e.g. front part of the D1) black. According to the dentition, the food is likely to consist of smaller fish (among others) - no information is available yet.
Occurrence
38 individuals were caught over the Tonga Ridge , some near Fiji and one on the Flinders Reef (off Queensland ), at a depth of approx. 300 m, apparently living meso- to bathy pelagic (probably sociable).
literature
- Izumi Nakamura, Nikolaj V. Parin: Snake mackerels and cutlassfishes of the world. An annotated and illustrated catalog of the Snake Mackerels, Snoeks, Escolars, Gemfishes, Sackfishes, Domine, Oilfish, Cutlassfishes, Scabbardfishes, Hairtails, and Frostfishes known to date (= FAO Species Catalog. Vol. 15 = FAO Fisheries Synopsis. No. 125 , Vol. 15). Food and Agriculture Organization of the United Nations, Rome 1993, ISBN 92-5-103124-X .
Web link
- Tonga-Escolar on Fishbase.org (English)