DISCRIMINANT FUNCTIONS FOR SEX IDENTIFICATION IN 2 MIDWIFE TOADS (ALYTES-OBSTETRICANS AND ALYTES-CISTERNASII)

Determining the sex of midwife toads in the field is not easy. Non-pre gnant females and males not tending clutches are difficult to sex with out dissection. We provide a method to determine the sex of individual s based on the study of linear variables. Fifteen morphological variab les were measured from samples of two species of midwife toad in the I berian Peninsula (Alytes obstetricans and Alytes cisternasii). Some va riables, corrected for the size of the animal, show significant differ ences between sexes. A discriminant analysis between the sexes in both species shows a high power for discrimination (95% in A. obstetricans and 97.6% in A. cisternasii). The significant variables in A. obstetr icans were: snout-urostyle length, distance between the nostrils, dist ance between the anterior end of the middle metacarpal tubercle and th e tip of the third finger, and distance from elbow to third finger tip . The significant variables in A, cisternasii were: head width, jaw bo ttom length, vertical diameter of the tympanum, distance between the n ostrils, and tibia-fibula length.