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The Geographic Variation of Ambystoma macrodactylum Baird, with the Description of Two New Subspecies

Denzel E. Ferguson
The American Midland Naturalist
Vol. 65, No. 2 (Apr., 1961), pp. 311-338
DOI: 10.2307/2422958
Stable URL: http://www.jstor.org/stable/2422958
Page Count: 28
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The Geographic Variation of Ambystoma macrodactylum Baird, with the Description of Two New Subspecies
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Abstract

The taxonomic history of the salamander Ambystoma macrodactylum is briefly reviewed. The recently described race A. m. croceum is accepted. Certain differences in color and color pattern of adult animals, especially as concern the dorsal band, indicate the existence of four additional races: A. m. columbianum and A. m. sigillatum, heretofore unrecognized subspecies; A. m. krausei and A. m. macrodactylum, restricted and redefined. For each subspecies, description, distinguishing characteristics, distribution, variations or known local deviants and a list of specimens examined are presented. Sexual dimorphism of the vent is described. Specimens of the four races are pooled into four samples and the means of 14 ratios formed from measurements and counts are compared using a completely randomized Factorial Design, the Analysis of Variance and the Individual Degree of Freedom based on the F distribution. A number of significant differences are demonstrated, lending additional support to the taxonomic separation of the species into the proposed races. A key to adults of the subspecies is given. Life history data pertaining to breeding, larval development and habitat preferences are presented and compared for the various races.

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