Remarkable Case of Anuran Sexual Size Dimorphism: Platymantis rhipiphalcus Is a Junior Synonym of Platymantis boulengeri

Abstract

Abstract Herein I synonymize the ranid frog Platymantis rhipiphalcus, from New Britain, with Platymantis boulengeri, from the same island. The four mensural characters originally used to separate these frogs covary continuously with body size, and sex is highly correlated with body size, with females much larger than males. Consequently, no features other than size separate these presumptive species, and specimens described as P. rhipiphalcus merely represent males and juvenile females of P. boulengeri. Males of P. boulengeri are here recognized as such for the first time, which leads to the discovery that this species has the most extreme sexual size dimorphism yet reported for any anuran. Female body length averages >3 times that for males, and female body mass averages >40 times that for males. The physical mechanics of reproduction in a species exhibiting such extreme size dimorphism are unknown but will certainly merit future investigation.