Sex identification and growth measurement in the black iguana (Ctenosaura pectinata) in juvenile and newborn stages

Abstract

THE PRESENT STUDY WAS CARRIED OUT TO IDENTIFY SEX IN THE BLACK IGUANA (CTENOSAURA PECTINATA), BY MEANS OF MORPHOLOGIC CHARACTERISTICS AT THE JUVENILE STAGE AND RETROSPECTIVELY, AT THE NEWBORN STAGE. SIXTY-TWO JUVENILES OF UNKNOWN SEX WERE USED IN THIS STUDY. THE CHARACTERISTICS MEASURED AT BIRTH TO DETERMINE SEX WERE: WEIGHT (G), SNOUT-CLOACA LENGTH (MM), TOTAL LENGTH (MM), HEAD, AND JAW LENGTH. IN THE JUVENILE STAGE, THE SAME MEASUREMENTS WERE RECORDED AT 6, 12, 18 AND 21 MONTHS OF AGE AS WELL AS THE DEVELOPMENT OF THE DORSAL CREST, FEMORAL PORES, AND SWELLING OF THE HEMIPENIS. RESULTS WERE STATISTICALLY ANALYZED USING CHI-SQUARE AND STUDENT'S T TESTS. IN THE 21-MONTH-OLD JUVENILE IGUANAS, SEXES WERE DISTINGUISHABLE (P < 0.01) BY MEANS OF THE DEVELOPMENT OF THE DORSAL CREST, FEMORAL PORES, SWELLING OF THE HEMIPENIS, WEIGHT AND HEAD LENGTH. DIFFERENCES WERE NOT OBSERVED (P > 0.05) IN MALES OR FEMALES AT BIRTH IN TERMS OF WEIGHT (G), SNOUT-CLOACA LENGTH (MM), TOTAL LENGTH, HEAD LENGTH AND JAW LENGTH. IT IS CONCLUDED THAT IN THE NEWBORN, THE MORPHOLOGIC CHARACTERISTICS EVALUATED DO NOT ALLOW MALES AND FEMALES TO BE DISTINGUISHED; HOWEVER THE DEVELOPMENT OF FEMORAL PORES, DORSAL CREST, HEMIPENIS, WEIGHT AND HEAD LENGTH DO ALLOW THE IDENTIFICATION OF SEX AT 21 MONTHS OF AGE.