Hybrid origin and status of the endangered Ilex sanqingshanensis revealed by molecular and morphological evidence

Abstract

Identification of natural hybrids considered as endangered species is of vital importance in biodiversity conservation and taxonomy, as natural hybrids will usually waste the conservation resource and obscure the divergences between distinct species. During the field surveys in the Sanqing Mountain, we found the endangered endemic species, Ilex sanqingshanensis, strictly co-occurred with I. ficoidea and I. pernyi and then supposed a hybrid origin for this taxon. Combing the molecular analyses of ITS and cpDNA (petA-psbJ + psbA-trnH) with the morphological analyses of eight leaf characters, we confirmed this taxon to be a hybrid between I. ficoidea and I. pernyi and accepted it as I. × sanqingshanensis. Despite the presence of intermediacy in morphology, this hybrid is sharply distinct from the two parents in all tested traits, misleading the botanists to treat it as a species. Considering the inadequacies of morphological distinctions in distinguishing holly hybrids, we have emphasized the necessity of molecular evidence for erecting Ilex species.