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Morphometrics, sexual dimorphism, and growth in the Angonoka tortoise (Geochelone yniphora) of western Madagascar

January 1, 2001

The most recent description of the morphology of the rare endemic Madagascar tortoise,Geochelone yniphora was based on fewer than 20 specimens. We collected morphological data for 200 free‐ranging tortoises from five populations over a four‐year period. Tortoises ranged in size from 43.5 mm carapace length at hatching to a maximum of 481 mm in an adult male. We were able to develop a logistic regression model to predict the sex of adult tortoises in one of the five populations using principal component analysis; the model correctly predicted the sex of 25 of 26 adult tortoises. Growth of 40 tortoises was monitored and as in other chelonians, the annual relative growth rate decreased with age. The relative growth rate in adults was approximately 5% per year as compared to approximately 16% in juveniles. Juvenile tortoises accrued one scute growth layer per year.

Citation Information

Publication Year 2001
Title Morphometrics, sexual dimorphism, and growth in the Angonoka tortoise (<i>Geochelone yniphora</i>) of western Madagascar
DOI 10.1080/21564574.2001.9635446
Authors Lora L. Smith, Miguel Pedrono, Robert M. Dorazio, Jack Bishko
Publication Type Article
Publication Subtype Journal Article
Series Title African Journal of Herpetology
Series Number
Index ID 70162305
Record Source USGS Publications Warehouse
USGS Organization Southeast Ecological Science Center

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