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The Life History of the Mexican Salamander Ambystoma ordinarium Taylor
James D. Anderson and Richard D. Worthington
Vol. 27, No. 2 (Jun., 1971), pp. 165-176
Stable URL: http://www.jstor.org/stable/3891075
Page Count: 12
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Ambystoma ordinarium inhabits and regularly reproduces in mountain streams in the state of Michoacan, Mexico. Eggs are deposited singly to undersurfaces of objects in the streams. Clutch size averaged 109. Ova have an average diameter of 2.8 mm and three distinct capsules not including the vitelline membrane and capsular cavity. Eggs laid in summer and winter, the uniform size classes of larvae, and the presence of animals in breeding condition summer and winter indicate reproduction through most or all of the year. Neoteny is common but some individuals metamorphose in all populations studied. Sexual maturity is attained at 70-75 mm SVL. Larvae and neotenic adults show some adaptations to the stream environment: reduced fins, reduced gills, loss of balancers, early development of limbs and digits. However, the persistence of the ypsiloid cartilage, fully developed fins in hatchlings, and only slight morphological changes in larvae towards the stream type suggest a recent invasion of the stream environment.
Herpetologica © 1971 Herpetologists' League