Oreochromis hunteri

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Oreochromis hunteri
Drawing from Catalog of the fresh-water fishes of Africa in the British Museum, Volume 3, 1915

Drawing from Catalog of the fresh-water fishes of Africa in the British Museum , Volume 3, 1915

Systematics
Order : Cichliformes
Family : Cichlids (Cichlidae)
Subfamily : Pseudocrenilabrinae
Tribe : Oreochromini
Genre : Oreochromis
Type : Oreochromis hunteri
Scientific name
Oreochromis hunteri
Günther , 1889

Oreochromis hunteri is a species of fish from the cichlid family (Cichlidae), which is endemic to Lake Chala on the border between Kenya and Tanzania.

features

Oreochromis hunteri reaches a length of 30 cm. Its body is about 2.8 times as long as it is high. The snout is long, the mouth is terminal. The teeth, arranged in rows, are very small. The pharyngealia is narrow. Their width is about 26% of the head length. It is covered with small teeth, which are mainly located in the back of the pharyngealia. The scales on the chest and stomach are very small and the transition from the larger scales on the sides of the body to the small chest and stomach scales is made abrupt in some individuals. In some specimens, the scales on the back are also small. The tail stalk is 1.3 times longer than it is high. Males have a light blue-gray basic color and show a dark pattern of spots on the head and on the sides of the body. The back is darker than the belly. In sexually mature males, the dorsal, anal and caudal fins and pectoral fins are dark. The dorsal fin has an orange border. Females are uniformly gray to olive in color with a light belly.

  • Fin formula: Dorsal XVI – XVII / 11–13; Anal III-IV / 10-16.
  • Vertebra: 31-34.

Way of life and exposure

Chala lake

Oreochromis hunteri occurs exclusively in the East African Chala Lake, a 4.2 km² crater lake with a maximum depth of 90 meters. The fish feed on algae and detritus and are maternal mouth brooders , i.e. the mother does the mouth brooding. Since the fish have become rare in the meantime, probably due to competition from three species of cichlid that were originally not native to Lake Chala, the species is now critically endangered. The feared hybridizations with Oreochromis cf. korogwe , which was introduced into the lake around 1990, have not yet occurred. The three species of cichlid introduced by humans are now more common than Oreochromis hunteri .

Systematics

The species was first scientifically described in 1889 by the German ichthyologist Albert Günther . A new genus was also introduced, oreochromis , which translates as "mountain chromis" (from gr. Óreios "mountain dwelling " and chromis ), as the fish come from the area around Kilimanjaro . Oreochromis hunteri is the type species of the genus Oreochromis . It belongs to a small radiation of three closely related Oreochromis species in the catchment area of the upper Pangani . Oreochromis jipe from Lake Jipe is the most closely related species to Oreochromis hunteri . Based on the genetic variability, it is concluded that the ancestors of Oreochromis hunteri arrived in Lake Chala about 25,000 years ago.

supporting documents

  1. ↑ a b Oreochromis hunteri on Fishbase.org (English)
  2. ↑ Ethelwynn Trewavas (1983). Tilapiine fishes of the genera Sarotherodon , Oreochromis , and Danakilia /. London: British Museum (Natural History). doi: 10.5962 / bhl.title.123198 , pages 369-374.
  3. ↑ Oreochromis hunteri in the endangered Red List species the IUCN 2006. Posted by: Bayona, JDR, Odhiambo, EA & Hanssens, M., 2006. Accessed April 27 of 2019.
  4. ↑ a b Dieleman, J., Muschick, M., Nyingi, WD & Verschuren, D. (2018): Species integrity and origin of Oreochromis hunteri (Pisces: Cichlidae), endemic to crater Lake Chala (Kenya – Tanzania). Hydrobiologia, April 2019, Volume 832, Issue 1. DOI: 10.1007 / s10750-018-3570-7
  5. ↑ Moser, FN, van Rijssel, JC, Ngatunga, B., Mwaiko, S. & Seehausen, O. (2018): The origin and future of an endangered crater lake endemic; phylogeography and ecology of Oreochromis hunteri and its invasive relatives. Hydrobiologia, April 2019, Volume 832, Issue 1. DOI: 10.1007 / s10750-018-3780-z
  6. ^ Albert CLG Günther (1889): On some fishes from Kilima-Njaro District. Proceedings of the Zoological Society of London, 1889 (1): 70-72.