Danionella

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Danionella
Systematics
without rank: Otophysa
Order : Carp-like (Cypriniformes)
Subordination : Carp fish-like (Cyprinoidei)
Family : Bärblings (Danionidae)
Subfamily : Danioninae
Genre : Danionella
Scientific name
Danionella
Roberts , 1986

Danionella is a genus of very small carp fish found in Myanmar and in the Jorai River, a tributary of the Brahmaputra in the north of the Indian state of West Bengal near the border with Assam .

features

Danionella species are only 11 to 17 mm long and are among the smallest carp fish and the smallest fish at all. They differ from all other carp fish in the small number of fin rays in the pectoral fins, the ventral fins and the caudal fin (7-9 / 9-7). They also have a characteristic large cartilage between the lower jaw and maxillary (absent in Danionella dracula ) and a cartilage that connects the fourth gill arch with the fifth ceratobranchial (lower “pharynx”). Both cartilages are not found in any other species of carp fish. Danionella differs from most other carp fish by the single row of four three-pronged pharyngeal teeth on the pharyngealia . Scales and barbels are missing, a sideline is not visible. The trunk is round in cross section. The number of vertebrae is 32 to 37. The front and rear chambers of the swim bladder are far apart, while the two chambers of all other carp fish are close together or the front part of the rear chamber connects directly to the front chamber. The bowel is simple and straight.

The dorsal fin sits over the back of the body and is supported by two simple and six branched fin rays. The large anal fin, which is roughly below the middle of the body, has two simple and 11 to 14 branched fin rays. The caudal fin is slightly forked. Their simple main fin rays are the same diameter as the branched ones. The innermost rays of the pectoral and pelvic fins are large and fully developed (only weakly developed in Rasbora ).

species

So far, four types have been described:

literature

Web links