Ruling out the boys from the girls: Can subtle morphological differences identify sex of the apparently monomorphic frog, Leiopelma pakeka?

• Published in: New Zealand journal of zoology Vol. 38; no. 2; pp. 161 - 171
• Main Authors: Germano, JM, Cree, A, Bishop, PJ
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.06.2011; Taylor & Francis Ltd
• Subjects: amphibian; Anura; Discriminant analysis; Frogs; Leiopelma pakeka; Maud Island Frog; sex identification; sexual dimorphism; sexual monomorphism; New Zealand
• ISSN: 0301-4223; 1175-8821
• DOI: 10.1080/03014223.2010.548076

New Zealand's endemic leiopelmatid frogs are all threatened with extinction. There is no obvious physical or behavioural difference between males and females of three of the four species and this lack of a sex identification technique is hindering conservation management. Twenty-one morphological features were measured for 67 live Leiopelma pakeka of known sex to determine whether a slight morphological difference existed that could be used for sex identification. Females were significantly longer in snout-to-vent length (SVL) than males, but as a great deal of overlap exists between sexes, this is not an ideal sex identification trait. No other physical characteristic was significantly different between sexes when adjusted for SVL. Discriminant analysis using a suite of traits was also unable to discriminate between sexes for frogs in the male-female overlap size range. The measurement of physical characteristics is inadequate for identifying sex in L.pakeka and other methods for sex identification must be developed. The reasons for the lack of sexual difference are unknown.