PECOS GAMBUSIA Gambusia nobilis (Baird and Girard, 1853) 



Order: ATHERINIFORMES Family; POECILIIDAE 



Distinguishing characteristics : A member of the nobilis species group distinguished by 

 having a large elbow on gonopodial ray 4a and this ray equal to or exceeding ray 4p; 

 lateral body stripe threadlike; caudal fin with dark margin; orominent dark margins on 

 scale pockets; predorsal streak strong . 



Present distribution : Now limited to spring-fed ditches about Toyahvale and to a spring 

 near Fort Stockton, both in Texas . 



Former distribution : Springs and spring-fed ditches of the Pecos River drainage in 

 southwestern Texas and eastern New Mexico . 



Status : Now extinct at the two localities (Leon and Comanche Springs, Texas) from 

 which it was described, and greatly depleted elsewhere. 



Estimated numbers : Not available . 



Fecundity : Unknown . 



Reasons for decline : Introduction of Gambusia affinis and other exotic predators; 

 desiccation of habitat (e.g., Comanche Spring ) . 



Protective measures already taken : None . 



Measures proposed : Designate the cave source of Phantom Lake Spring and a suitable 

 length of its outflow as a wildlife monument; remove exotic species and erect barriers 

 against their re-entry. 



Number in captivity : None . 



Breeding potential in captivity : Unknown . 



Remarks : This species is now common only in the outlet ditch of Phantom Lake Spring 

 near Toyahvale, Texas. Data provided by Dr. Clark Hubbs, University of Texas, Austin. 



Reference : 



Hubbs, C. and V . G. Springer. 1957. A revision of the Gambusia nobilis species 

 group, with description of three new species, and notes on their variation, 

 ecology, and evolution . Texas Jour. Sci., Vol. 9, No. 3, p. 279-327. 



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