Xiphophorus nigrensis és una espècie de peix de la família dels pecílids i de l'ordre dels ciprinodontiformes.[2]
Tant els mascles com les femelles poden assolir els 6 cm de longitud total.[3]
Es troba a Amèrica: Mèxic (San Luis Potosí).[3]
Xiphophorus nigrensis és una espècie de peix de la família dels pecílids i de l'ordre dels ciprinodontiformes.
Xiphophorus nigrensis, the Panuco swordtail, is a species of fish in the family Poeciliidae[2] that is endemic to a small part of the Pánuco River basin in Mexico.[1][3][4]
Being a small swordtail, Xiphophorus nigrensis was originally considered a subspecies of X. pygmaeus.[5] Today it is recognized, along with X. multilineatus, as the closest related species to X. pygmaeus.[6] The three species form a clade within the larger clade of northern swordtails.[7] The similarity of the large males of X. nigrensis to the small males of X. cortezi, another northern swordtail, points to a close evolutionary relationship between these two species.[5]
The body of Xiphophorus nigrensis is larger and deeper than that of X. pygmaeus. The males possess on their caudal fin a moderately to well-developed sword set off by a black line, from which the specific epithet nigrensis (niger meaning black and ensis sword in Latin) is derived. Pregnant females exhibit a dusky gravid spot on their bellies. Larger individuals are deeper-bodied and develop brilliant iridescent blue on their sides and flanks, which may somewhat conceal their midlateral black stripe.[5]
Populations regularly contain both large (up to 40 mm) and small adult males (down to 18 mm).[5] Large males possess swords, while small males do not. Small males are slender and of solid gold color.[7]
Xiphophorus nigrensis is found in Rio Choy.[7] The species inhabits clear, deep, fast-flowing waters along undercut slopes of river and stream beds. The depth can be as great as 3 m (9.8 ft).[5]
Xiphophorus nigrensis readily hybridizes with X. pygmaeus; in fact, females of the latter species prefer X. nigrensis males to those of their own species because large X. nigrensis males court females while X. pygmaeus males merely sneak up and chase them instead. Small X. nigrensis males also exhibit sneak-chase behavior.[8]
Xiphophorus nigrensis, the Panuco swordtail, is a species of fish in the family Poeciliidae that is endemic to a small part of the Pánuco River basin in Mexico.
Xiphophorus nigrensis es una especie de peces de la familia de los pecílidos en el orden de los ciprinodontiformes.[2]
Tanto los machos como las hembrass pueden alcanzar los 6 cm de longitud total.[3]
Se encuentran en América: México (Estado de San Luis Potosí).[3]
Xiphophorus nigrensis es una especie de peces de la familia de los pecílidos en el orden de los ciprinodontiformes.
Xiphophorus nigrensis Xiphophorus generoko animalia da. Arrainen barruko Poeciliidae familian sailkatzen da.
Xiphophorus nigrensis Xiphophorus generoko animalia da. Arrainen barruko Poeciliidae familian sailkatzen da.
Xiphophorus nigrensis is een straalvinnige vissensoort uit de familie van de levendbarende tandkarpers (Poeciliidae).[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1960 door Rosen.
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尼加拉瓜劍尾魚，為輻鰭魚綱鯉齒目鯉齒亞目花鳉科的其中一種，分布於中美洲墨西哥Panuco河流域，體長可達6公分，棲息在植被生長、水流湍急的溪流，屬肉食性，生活習性不明，可作為觀賞魚。
这是一篇關於魚類的小作品。你可以通过编辑或修订扩充其内容。 
