Matthiola shehbazii Ranjbar & Karami (Brassicaceae) from Markazi Province, central Iran is described as a new species. Diagnostic characters, description, and taxonomic comments on the species are given. The geographical distribution of the new species is also mapped. The IUCN threat category and observations on its population are noted. Its morphological characteristics are compared with M. ovatifolia Boiss. as the most closely related species. Matthiola shehbazii is an allotetraploid plant and possesses 2n 4x 24 chromosomes, consistent with the proposed dibasic numbers of x 6 and x 7. The general meiotic behavior in the new species was nearly regular, with bivalent pairing and normal chromosome segregation at meiosis. However, some meiotic abnormalities were observed in the species including bridges and laggards. Results from morphology and chromosome count supported the separation of M. shehbazii as a new distinctive species.
Pollen morphology of 12 species, representing genera of the tribes Brassiceae, Conringieae, Isatideae and Plagiolobeae were studied using light microscopy (LM) and scanning electron microscopy (SEM). The results demonstrated that the polar diameter, pollen exine ornamentation, mesocolpium width, and exine thickness have important systematic significance. Pollen grains in these genera were tricolpate and their shapes varied from prolate to perprolate, with the polar axis length ranging from 30.28 to 41.05 mm and the equatorial axis length ranging from 17.21 to 23.36 mm. However, fine details can be used to distinguish pollen grains of the different species within the genera. The exine ornamentation varied among genera within the tribes and among species within the same genus. Three pollen types are distinguished based on lumen size. All the studied tribes' pollen were heterogeneous, with reticulate, microreticulate (Conringia orientalis, Plagioloba derakii), or macroreticulate (Moricandia sinaica) ornamentation. The exine thickness ranged from 0.75 to 2.60 mm. Pollen characteristics support: (i) two distinct pollen types (viz. Conringia austriaca and Iljinskaea planisiliqua types) in all four tribes; (ii) the similarity of the pollen shape between tribes Isatideae and Brassiceae; (iii) the transfer of P. crenulata from Zuvanda to Plagioloba, and of I. planisiliqua from Conringia to Iljinskaea. Plagioloba clavata displays great variation in pollen morphological characters and needs to be further studied. A key to the species of the genera was also provided.
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