Phylogeny of Callibaetis (Ephemeroptera: Baetidae) based on morphology of nymphs and adults

Abstract

Callibaetis is considered to be one of the most problematic genera among mayflies by a series of taxonomic inaccuracies that have accumulated over the last two centuries. Despite these taxonomic problems, two independent hypotheses of species groups have been proposed. In the first hypothesis, three species groups for North America were proposed, and in the second, three species groups were proposed for South American. In these hypotheses, the generic delimitation and monophyly of Callibaetis have not been evaluated under a cladistic framework. Taking this into account, the objectives of this study were to verify the monophyly of Callibaetis and whether the groups of species proposed for the genus are corroborated as natural. The matrix included 128 morphological characters and one habitat character, 119 discrete characters were compiled (101 of nymphs and 18 of adults), and six imaginal characters are related to pigmentation pattern. Continuous characters were ratios and were represented by 10 characters (nine for nymphs and one for adults). The data set was analysed under implied weights. Group support was estimated with relative Bremer support and frequency differences. The results corroborated the monophyletic nature of Callibaetis and the generic status of Callibaetoides; however, the groups proposed for North and South American Callibaetis species were not corroborated. Our study indicated four groups of species for the genus, which we proposed as subgenera: Callibaetis, Abaetetuba subgen. n. Aiso subgen. n. and Cunhaporanga subgen. n. © 2016 Royal Swedish Academy of Sciences