CLEAR CREEK GAMBUSIA Gambusia heterochir (Hubbs, 1957) 



Order: ATHERINIFORMES Family: POECILIIDAE 



Distinguishing characteristics : Pectoral fin of male with deep indentation; no yellow 

 pigment in dorsal or anal fins; dusky lateral stripe indistinct; "elbow" of gonopod very 

 large . 



Present distribution : Headwaters of Clear Creek, 10.4 miles west of Menard, Menard 

 County , Texas . 



Former distribution : Probably somewhat greater than present . 



Status : In peril . Threatened by competition with Gambusia affinis and proposed 

 construction of a dam, thereby altering its restricted habitat. 



Estimated numbers : Fewer than 1,000 . 



Fecundity : Adequate when undisturbed . 



Reasons for decline : See Status , above . 



Protective measures already taken : None . 



Measures proposed : Set aside extreme headwaters of Clear Creek as a wildlife sanctuary. 



Number in captivity : None . 



Culture potential in captivity : Satisfactory . 



Remarks : The existence of this very localized endemic is not only threatened by its 

 very restricted distribution and the proposed dam but also by possible genetic swamping 

 with G. affinis , with which it hybridizes. Data submitted by Dr. Robert R. Miller, 

 University of Michigan. 



References: 



Hubbs, C. 1957. Gambusia heterochir , a new poeciliid fish from Texas, with 



and account of its hybridization with G. affinis . Tulane Stud. Zool . , Vol. 5, 

 No. 1, p. 1-16. 



. 1959 . Population analysis of a hybrid swarm between Gambusia 



affinis and G . heterochir . Evolution, Vol. 13, No. 2, p. 236-246. 



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