Oxytropis ikhbogdicus (Section Mesogaea, Fabaceae), A New Species From Mongolia Based on Morphological and Molecular...

Oxytropis ikhbogdicus, a new species endemic to Mongolia, belonging to section Mesogaea (Fabaceae), is described and illustrated. The new species was resolved by phylogenetic analysis based on the complete plastome genome, as well as morphological characteristics. Morphologically, the new species closely resembles O. kansuensis, O. ochroleuca and O. ochrocephala within the section Mesogaea; but it is distinguished by stems with 1 or 2 conspicuous internodes (vs. stems with 2-5 conspicuous internodes in O. kansuensis, O. ochroleuca, and O. ochrocephala); calyx campanulate, 6-7 mm long (vs. campanulate, 6.5-11.5 mm long in O. kansuensis; broadly cylindric, 7-8 mm long in O. ochroleuca; cylindric, 6-8 mm long in O. ochrocephala); and standard 8.5-9.0 mm long, lamina rhombic-oblanceolate, apex rounded to emarginate (vs. 10-17 mm long, lamina ovate, apex emarginate in O. kansuensis; 12-16 mm long, lamina orbicular-ovate, apex 2-lobed in O. ochroleuca; 10-17 mm long, lamina broadly obovate, apex emarginate in O. ochrocephala). Additionally, O. ikhbogdicus is geographically distinct from other morphologically similar species, found on Altai Mountain in Mongolia, while O. ochroleuca occurs in Tien Shan in China, Kazakhstan, and Kyrgyzstan, O. kansuensis and O. ochrocephala occur Qinghai-Tibetan Plateau in China.