Introduction

The Cyanus group was first described by Miller (1754) as a genus. Subsequently, Candolle (1838) reduced this genus to a section of Centaurea L., a position followed by some botanists (Bentham, 1873; Boissier, 1875; Hoffmann, 1893; Stefanov & Gheorghiev, 1931; Dittrich, 1968; Wagenitz, 1975). Others recognized it as a subgenus of Centaurea (Czerepanov, 1963; Dostál, 1976). Molecular studies of Centaureinae by Garcia-Jacas et al. (2001) and Wagenitz et al. (2006) have shown that the Cyanus group is sister to the genus Centaurea s.s. Currently the most widely-accepted taxonomic position recognizes Cyanus as a separate genus (Soják, 1972; Holub, 1977; Dostál, 1984; Bancheva & Raimondo, 2003; Greuter, 2003, 2008; Hellwig, 2004; Bancheva & Greilhuber, 2006; Wagenitz, 2006; Bancheva & Stoyanov, 2009; Kaya & Bancheva, 2009; Olšavská et al., 2009, 2011; Ranjbar & Negaresh, 2012; Olšavská et al., 2013; Ranjbar et al., 2013a, 2013b; Stoyanov, 2016).

Cyanus Mill. is distributed throughout central and southern Europe, North Africa, Asia Minor, and the Caucasus, with some species appearing as far east as Iran and Afghanistan and currently includes 32 species (Hellwig, 2004; Bancheva & Stoyanov, 2009; Kaya & Bancheva, 2009; Boršić et al., 2011; Ranjbar & Negaresh, 2012; Olšavská et al., 2013; Ranjbar et al., 2013a, 2013b; Stoyanov, 2016). The genus is distinct within the Centaureinae by phyllaries with scarious and spineless appendages that are decurrent nearly to the phyllary base, and by blue or purplish blue florets (with only a few exceptions of cream- or pale pink-flowered taxa) (Wagenitz & Hellwig, 1996; Boršić et al., 2011). This genus has been divided into annual group containing 6 species and perennial group containing 26 species (Olšavská et al., 2013). Annual species show a complex dysploid chromosome series with gametic chromosome numbers x = 8, 9, 10 and 12, whereas perennial species are more uniform in their gametic chromosome numbers, with x = 10 or 11 (Wagenitz & Hellwig, 1996; Uysal et al., 2009; Boršić et al., 2011; Olšavská et al., 2013).

Recently, Bancheva & Kaya (2015) described Centaurea raimondoi Bancheva & Kaya as a new species for the flora of Turkey. They did correctly place it in Cyanus but, as they did not recognize that genus, they included it in Centaurea. According to them, it is closely related to Cyanus eflanensis Kaya & Bancheva. A detailed comparison of the description and type photograph confirms that Centaurea raimondoi belongs to the Cyanus because of its violet-blue florets, peripheral florets radiant and devoid of staminodes, phyllary appendages spineless with scarious margin decurrent nearly to the base. Indeed, in agreement with Bancheva & Kaya's treatment (Bancheva & Kaya, 2015) and the current concept of Cyanus, we propose the new combination. With this species included, the total number of species in Cyanus increases to 33.

Nomenclature and taxonomy