Cytology and morphology of Pseudoroegneria deweyi (Poaceae: Triticeae): a new species from the foot hills of the Caucasus Mountains (Russia)
Cytological and morphological characteristics of a new species, Pseudoroegneria deweyi K. B. Jensen, from the Karachayevo-Cherkesskaya Avtonomnaya Oblast' Region of Russia are described. This species is cytologically stable, genomically similar to Pseudoroegneria tauri, highly fertile (cross-pollinating), and morphologically unique compared with most other species in the genus. Pseudoroegneria deweyi differs from other closely related species in the number of rachis nodes in the inflorescence. Pseudoroegneria stipifolia (2n = 2x = 14, SS) and Agropyron cristatum (2n = 2x = 14, PP) were used as male parents in crosses with P. deweyi. All three P. deweyi accessions studied were tetraploids (2n = 28) and behaved meiotically as allotetraploids with a mean chromosome association of 0.03 I + 13.30 II + 0.03 III + 0.26 IV per cell. In the hybrid P. deweyi × A. cristatum, average chromosome association was 5.92 I + 4.55 II + 1.83 III + 0.09 IV per cell, while the average chromosome association in P. deweyi × P. stipifolia was 4.98 I + 5.23 II + 1.73 III 0.04 IV per cell. Pseudoroegneria deweyi joins P. tauri as the only other known naturally occurring species with the genomic formula of SSPP. Cluster analysis of 21 morphological characters supports the inclusion of P. deweyi as part of the genus Pseudoroegneria rather than Agropyron. Key words: Agropyron, Pseudoroegneria, chromosome pairing, meiosis, Triticeae, new species.