Northern mountain sword bearer
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Northern mountain swordtail ( Xiphophorus nezahualcoyotl ), male |
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| Xiphophorus nezahualcoyotl | ||||||||||||
| Smokingberger , Kallman & Morizot , 1990 |
The Northern Mountain swordtail ( Xiphophorus Nezahualcoyotl ) is a freshwater ornamental fish from the family of viviparous tooth-carps .
features
This small representative of the swordtail reaches a body length of four to five centimeters, females grow up to six centimeters. In addition, the males have a greenish-yellow sword that is up to four centimeters long, outlined in black and slightly curved upwards. The basic body color is gray-brown or gray-blue in both sexes, the abdominal region remains somewhat lighter. Four to five dark zigzag lines adorn the side of the body. The pages shimmer bluish in the light. All fins are slightly yellowish, the dorsal fin also has a number of dark spots. Some males have a dark spot at the base of the caudal fin. In both sexes, irregular black spots called macromelanophores can be present on the sides of the body.
Occurrence and way of life
The occurrence is limited to the catchment area of the Río Tamesí , with the Río el Salto , Río Tanchachin and Río los Gatos and their tributaries, in the Mexican state of San Luis Potosí . The fish can be found there at water temperatures of 22 to 24 ° C in strong currents near aquatic plants. Nothing is known about the diet in nature, the diet in the aquarium should be varied and consist of live, frozen and flake food .
Reproduction
This species of fish is viviparous . In order to fertilize the eggs in the female's body, the males have the so-called gonopodium , which is typical of the viviparous toothcarps . After a gestation period of an average of 24 days, the females give birth to between 20 and 40 fry. The fry are initially seven to eight millimeters long and grow slowly.
Systematics
For a long time, the northern mountain swordtail was considered a subspecies of the Montezuma swordtail ( Xiphophorus montezumae ). But as early as 1964, employees of the University of Hamburg had doubts about the species belonging to X. montezumae and called him Xiphophorus "Hamburg 1964". However, it was not described as an independent species until 1990.
Together with its sister species Xiphophorus montezumae and Xiphophorus continens it forms a monophyletic group . Of the representatives of this group living in the highlands of Mexico, it has the northernmost distribution area, from which the German name is derived.
Origin of name
Due to the close relationship to the Montezuma swordtail and because it was long regarded as its subspecies, the authors of the first description decided to name it after Nezahualcóyotl , a ruler equal to Montezuma , as well as philosopher and poet.
Individual evidence
- ↑ Lothar Wischnath: Atlas of Livebearers of the World , 1993, ISBN 0-86622-368-1 , p 246
- ^ Mary Rauchberger, Klaus D. Kallman, Donald C. Morizot: Monophyly and Geography of the Río Pánuco Basin Swordtails (Genus Xiphophorus ) with Descriptions of Four New Species. In: American Museum Novitates. , No. 2975, 1990, ISSN 0003-0082 , p. 22 ( [1] ).
literature
- Lothar Wischnath: Atlas of Livebearers of the World. 1993, ISBN 0-86622-368-1 .
Web links
- Northern Mountain Sword Bearer on Fishbase.org (English)