Retroculus
| Retroculus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Retroculus lapidifer , drawing from Castelnau's Expédition dans les parties centrales de l'Amérique du Sud, de Rio de Janeiro à Lima, et de Lima au Para: exécutée par ordre du gouvernement Français pendant les années 1843 à 1847. - Paris: P. Bertrand , 1850-1857 |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name of the tribe | ||||||||||||
| Retro culini | ||||||||||||
| Kullander , 1998 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Retroculus | ||||||||||||
| Eigenmann & Bray , 1894 |
Retroculus is a genus of South American cichlids . The scientific name alludes to the eyes, which are far back compared to other cichlids ( Latin : retro = backwards; oculus = eye).
features
Retroculus species are 14 to 20 centimeters long. Their shape is similar to that of the geophagine cichlid genera Geophagus and Satanoperca . The head is big and looks beefy, the thick-lipped mouth is pointed. The eyes are far back and above. The color of the fish is greenish to brownish. The head and torso are patterned with shiny metallic dots and lines. There is a black spot in the back of the dorsal fin. The caudal fin shows clear vertical stripes in two species, in Retroculus lapidifer it is unstriated . The fins are not drawn out long, only the middle ray of the broad, short pectoral fins is elongated. The swim bladder has receded. This means that retroculus species cannot float in the water. When resting, they support themselves with their pelvic fins on the bottom of the water. The number of scales in a central longitudinal row (mLR) is 34 to 41. The ventral scales are small.
Fin formula : Dorsal XIV – XVII / 10–12, Anale III / 6–7.
Plesiomorphies , which show the originality of the genus, are the five sensory pores on the lower jaw, the seven sensory pores on the gill cover , the lips, which resemble those of African cichlids, and the numerous gill rays (10 to 15).
Way of life
Retroculus species live in clear water rivers of the Guiana Mountains and the Eastern Brazilian Shield in rapids and areas with strong currents. They look for their food at the bottom of the water. Mosquitoes , caddis flies , and mayfly larvae make up the bulk of their diet.
Reproduction
The reproduction is little known. The retroculus species dig a pit in the bottom of the water during the breeding season, in which the eggs are laid. The pit can reach a diameter of half a meter and is covered with larger pebbles after the eggs are laid to protect the eggs. Both parents take part in the brood care. Observations in aquariums do not extend beyond the first day after the eggs were laid; the eggs may then have been eaten by the parents.
Systematics
Retroculus was originally assigned to the cichlid subfamily Geophaginae. The Swedish ichthyologist Sven O. Kullander found in 1998 that the genus occupies a basic position within the New World cichlids and placed the genus in its own subfamily, the Retroculinae.
Types and distribution
There are four scientifically described species that are found in northeastern South America.
- Retroculus acherontos Landim et al., 2015, catchment area of the Rio Tocantins .
- Retroculus lapidifer (Castelnau, 1855), 20 cm, Southeast Amazonia (catchment area of the Rio Tocantins and the Rio Araguaia ).
- Retroculus septentrionalis Gosse, 1971, 20 cm, Oyapock between French Guiana and Brazil .
- Retroculus xinguensis Gosse, 1971, 14 cm, Rio Xingu .
Two other species from the Rio Tapajós and the Rio Tocantins are still undescribed.
literature
- Claus Schaefer: Retroculus. In: Claus Schaefer, Torsten Schröer (Hrsg.): The large lexicon of aquaristics. Eugen Ulmer, Stuttgart 2004, ISBN 3-8001-7497-9 , pp. 854 f.
Web links
- Retroculus on Fishbase.org (English)
- Website of the Swedish cichlid specialist Sven O. Kullander: Retroculus Eigenmann & Bray