Arapaima agassizii
| Arapaima agassizii | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Contemporary illustration from 1829 by Louis Agassiz and Johann Baptist von Spix . Above presumably the holotype (according to Stewart), below the osteological section of the holotype. |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Arapaima agassizii | ||||||||||||
| ( Valenciennes in Cuvier & Valenciennes, 1847) |
Arapaima agassizii is a little-known freshwater fish from the order of Knochenzünglerartigen (Osteoglossiformes). The fish wasdescribedas Vastres agassizii by the French zoologist and ichthyologist Achille Valenciennes in 1847, but was later synonymous with Arapaima gigas . The holotype , the only known specimen of the species to date, wascaughtbetween 1817 and 1820 in a now unknown location in the lowlands of the Brazilian Amazon basin . He was lost in World War II . However, since the first description containedprecise osteological drawings, the species was re-described and revalidated in 2013 by the American ichthyologist Donald Stewart. The exact range of the species as well as its possible endangerment remain unknown for the time being.
features
Arapaima agassizii differs from Arapaima gigas by a total of nine morphological features. The number of teeth on the dental (the tooth-bearing part of the lower jaw) is 44 (21-37 in Arapaima gigas ), the number of teeth on the maxillary is 43 (21-38 in A. gigas ). The diameter of the orbit (eye socket) is 1.5% of the standard length (SL), the distance between the orbita is 4.1% of the SL, while in other arapaimas it is 5.3 to 6.5% of the SL and the The diameter of the orbit can be up to 2.8% of the SL. The paired parietal bones have pronounced, pointed posterior outgrowths that curve in a curvilinear manner towards the midline. These are missing in A. gigas . The caudal stalk has a length of 9.7% of the standard length (3.2 to 5.5% in A. gigas ), so that the distance between the dorsal and anal fin and the caudal fin is greater. The anal fin has only 26 fin rays (30 to 40 in A. gigas ). Their base is significantly shorter than that of the dorsal fin. The dorsal and anal fins are much lower than in A. gigas . The tip of the first pectoral fin ray towards the body is roughly the same size as the subsequent pectoral fin rays, while it is significantly enlarged in A. gigas .
literature
- Donald J. Stewart 2013. Re-description of Arapaima agassizii (Valenciennes), a Rare Fish from Brazil (Osteoglossomorpha: Osteoglossidae). Copeia . 2013 (1): 38-51, doi: 10.1643 / CI-12-013
- Leandro Castello, Donald J. Stewart: Assessing Cites Non-Detriment Findings Procedures for Arapaima in Brazil, online (PDF; 752 kB)
- Valenciennes, A. in Cuvier, G. & A. Valenciennes (1847): Histoire naturelle des poissons. Tome dix-neuvième. Suite du livre dix-neuvième. Brochets ou Lucioïdes. Livre vingtième. De quelques familles de Malacoptérygiens, intermédiaires entre les Brochets et les Clupes . P. Bertrand, Paris. v. 19: 456.
- Reis, RE, Kullander, SO and CJ Ferraris Jr. (2003): Check list of the freshwater fishes of South and Central America . CLOFFSCA. EDIPUCRS, Porto Alegre.
Web links
- Arapaima agassizii on Fishbase.org (English)