TAXONOMIC NOTES ON ONOSMA SECT. APONOSMA FROM IRAN (BORAGINACEAE)

Abstract

Onosma mahabadensis Ranjbar & Almasi (Boraginaceae), a new species endemic to Iran, is described. This species belongs to Onosma sect. Aponosma DC. and is confined to the western part of Iran (West Azerbaijan Province). It is closely related to Onosma sericea Willd. and is distinguished by its subpatent-bristly indumentum (vs. appressed-sericeous) with sparse short hairs (vs. dense), and bracts 14–16 mm long (vs. 6–8 mm long). A cytogenetic analysis indicates that Onosma mahabadensis is a tetraploid species, 2n = 4x = 32, consistent with the proposed base number of x = 8 for Onosma sect. Aponosma