After the discovery of a female sex call emitted by the Fiji lslands Treefrog Platymantis vitiensis (Boistel & Sueur, 1997), we researched the anuran female vocalisations already reported in the herpetological literature. Although female vocalisations are commonly supposed to be extremely rare, it appears that they are produced by 58 species, belonging to 29 genus of 13 families in all regions excepted Australia. Females are able to produce six types of vocalisations: sex call, courtship call, territorial call, release call, aggressive call and distress call. The sex, courtship and territorial calls illustrate a possible case of sex role reversal. The aggressive call is an aposematic mimetism similar to the warning hiss of snakes. These vocalisations share common acoustic features probably explained in part by the lack of vocal sacs: (1) a fundamental frequency of greater intensity (dominant frequency), (2) a fundamental frequency lower than those of males, related to the larger female body size (except the case of Platymantis vitiensis), (3) a lower sound pressure level than those of males. Following Bush (1997), the emergence of such sound production is related to eco- ethological factors as the operational sex ratio and the microhabitat. The population density and the period of reproduction may be also determinant. Furthermore, the female calls have undoubtedly evolved in correlation with the reproductive and parental investments as it is suggested by Marquez & Verrel (1991). Because both "ancestral'' and "modern'' families are concerned, female vocalisations have probably emerged independently several times during the evolution of Amphibians.
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