Hybrid origin and hybrid 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 taxonomy and biodiversity conservation, as natural hybrids will usually waste the conservation resource and efforts. During 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 hypothesized a hybrid origin for this taxon. Combing molecular analyzes of the nrDNA ITS and cpDNA (petA-psbJ + psbA-trnH) with morphological analyzes of eight leaf characters, we confirmed that this taxon is truly a hybrid between I. ficoidea and I. pernyi and we therefore to rename it as I. × sanqingshanensis. Despite the presence of intermediate morphological characteristics, this hybrid is sharply distinct from the two parents in almost all tested traits, misleading botanists who treated 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.