Allium species of section Rhizomatosa, early members of the Central Asian steppe vegetation

Abstract

The genus Allium is one of the largest genera in the family of Amaryllidaceae. It comprises over 1000 species, and the number is still increasing. The new intergeneric classification system, based on molecular sequence data, subdivided the genus into 15 subgenera and more than seventy sections. In some sections, the phylogenetic position of species remained unresolved. This is also the case regarding the sections Caespitosoprason and Rhizomatosa. These two sections are confined to Central Asia, where they inhabit steppe habitats. For this study we conducted a phylogenetic analysis of most of the taxa of sections Caespitosoprason and Rhizomatosa with the nuclear marker ITS and three different chloroplast regions (trnQ-rps16, trnL-trnF and rpl32-trnL). Taxonomical remarks, identification key and distribution maps for all species of section Rhizomatosa (including all species of section Caespitosoprason) are presented. A newly discovered Allium bellulum from the Katun Valley (Altai, Russia) was cytologically compared (flow cytometry and karyology) with the other two known localities from Tuva, Russia, and the Buchtarma Valley, Altai, Kazakhstan, and the disjunctive distribution discussed. Divergence time estimates of the species of section Rhizomatosa and their distribution are in agreement with the origin and climate/landscape history of the Central Asian steppe since the Lower Miocene.