1 Introduction
Roegneria C, Koch was erected and circumscribed by Koch (1848) according to Roegneria caucasica C. Koch as the type species. Nevski (1934) played a major role in popularizing the genusRoegneria , which he recognized distinct from AgropyronGaertner as an independent genus and described 49 species ofRoegneria . Tzvelev (1976) and Chen et al., (2006) includedRoegneria in Elymus because of their many commonly morphological characters, e.g., plants usually tufted; lemma lanceolate-oblong, rounded abaxially, 5-veined, veins connivent at apex. Despite the criteria used, there is morphological disagreement over circumscription of Elymus and Roegneria , andRoegneria is distinguished from Elymus by single spikelet per rachis node with lanceolate glumes and short and broader palea as well as glume retention after caryopsis abscission. Based on these morphological disagreements as a guide to resolve taxonomic treatment, Baum et al. (1991) recognized only one genus. Cytogenetics and molecular phylogeny provided additional support for the Roegneria as an independent genus (Lu et al., 1988; Yen et al., 2011; Fan et al., 2013), corresponding to genome system of classification in Triticeae. Since then, Roegneria is a large genus in the wheat tribe, Triticeae (Poaceae), which includes approximately 120 species that are of Asian origin and distributed in the Qinghai–Tibetan Plateau, Central Asia, East Asia, West Asia and South-east Europe (Baum et al., 1995; Yen & Yang, 2011). The largest number is found mainly in the mountains of the Qinghai–Tibetan Plateau, with 33 species being recorded. Most species of Roegneria can usually be recognized in the field by a combination of characters: (a) lack of underground rhizomes; (b) spikes often slightly curved to erect, with arrangement of spikelets nearly parallel to and appressed to rachis and only one per node, with long rachis internodes; (c) spikelets functionally disarticulating above the glumes (Baum et al., 1995). Cytologically, all the species ofRoegneria are allotetraploids with StY genomes (Yen & Yang, 2011). The St genome is derived fromPseudoroegneria (Nevski) Á. Löve (Löve, 1984; Wang et al., 1994). It is unknown where the Y genome originates, although it is a fundamental Roegneria genome (Yen & Yang, 2011). Dewey (1984) considered that the Y genome has its origin in Central Asia or the Himalaya region, and may be extinct. Extensive cytogenetic and molecular studies have suggested that the St(Pseudoroegneria ), W [Australopyrum (Tzvelev) Á. Löve], V [Dasypyrum villosum (L.) Candargy], and Xp [Peridictyon O. Seberg, S. Frederiksen & C. Baden] genomes are potential donors of the Y genome (Liu et al., 2006; Sun & Komatsuda, 2010; Fan et al., 2013; Lei et al., 2022; Liu et al., 2022).
Here, we described a new species of Roegneria that was discovered from the Hengduan Mountain Region during an expedition to the Qinghai-Tibetan plateau in 2021 to collect germplasm of various members of the Triticeae. The new species was discovered in stony slope of Haba Snow Mountain with about 3200m and 2500m altitude. A few weeks later, it was collected in stony slope of Yulong Snow Mountain with approximately 3200m altitude. The two localities are more than 90 km apart. This study conducted on morphological observations, sampling of multiple accessions, genomic in situ hybridization (GISH), and phylogenetic reconstruction methods. Our goal was to determine whether this was the case as a new species within Roegneria and, if so, to determine the genomic constitution of the new species and provide it with an appropriate name.