A re-examination of the circumscription of Saxifraga mengtzeana (Saxifragaceae)

Abstract

In the Flora of China account (Pan et al. 2001) of Saxifraga mengtzeana Engl. & Irmsch., eight synonyms were attributed to it and one variant, recognised as S. epiphylla Gornall & Ohba, was split from it. This study re-evaluates the taxonomic status of some of the synonyms and of the segregated species in the light of new evidence presented here. Morphological and molecular evidence demonstrate that populations from north-western Yunnan and Sichuan are genetically differentiated from those in south-eastern Yunnan and neighbouring Guangxi. Observations in the field and in cultivation show that the peltate petiole attachment diagnostic of S. mengtzeana var. peltifolia Engl. & Irmsch. is developmentally labile. Similar observations combined with molecular data show that viviparous phenotypes, formerly treated as S. epiphylla, although largely under genetic control, occur sporadically throughout the ranges of both northern and southern taxa. Populations from north-western Yunnan and Sichuan are best recognised as S. geifolia Balf.f., whereas those from south-eastern Yunnan and neighbouring Guangxi are S. mengtzeana. Peltate-leaved variants of the latter are given no status and are relegated to complete synonymy. Viviparous phenotypes of S. mengtzeana are demoted to the rank of forma, as f. epiphylla; analogous phenotypes of S. geifolia are newly described as f. vivipara. Keywords China, Saxifragaceae, Phylogeny, Morphology, Taxonomy

Saxifraga cataphracta (Saxifragaceae), a new species from Southwest China

“…It is worth noting that S. geifolia was restored, and S. epiphylla (with foliar embryos) was synonymized underS. mengtzeana recently (Zhang et al 2022a). Of these three species with foliar embryos, S. cataphracta is morphologically similar to S. geifolia , as the leaf blade of these two species is rotund to reniform, more or less isodiametric, while the leaf blade ofS.…”