In: Phyton 53, Fasc. 2 (2013), S. 185–220, with 40 figures
Key words: Boraginaceae, Lithospermeae, Onosma euboica Rech. f., Onosma heterophylla Griseb., Onosma pseudoeuboica Teppner & Karl spec. nova. – Chromosome numbers, karyology, morphology, systematics, taxonomy. – Isoholotype, nomenclature. – Flora of Greece.
The asterotrichous Onosma euboica Rech. f. is a narrow endemic of North Euboea. It is characterized by relatively wide stem leaves of which only the lowermost ones show a short petiole-like part. The species was shown to be diploid with 2n = 14 or n = 7 chromosomes. Plants from N Euboea with narrower leaves and in the lower 1/3 – 1/2 of the flowering stems with distinct petiole-like parts were included in O. euboica till now. However from one population they were proven to be tetraploid with 2n = 26 and n = 13 chromosomes. Thus, these plants are here described as a new species, Onosma pseudoeuboica Teppner & Karl. The species is most probably of allotetraploid origin with diploid O. heterophylla as one parent. Plants from the Nom. Karditsa (Greek mainland), which were also included in O. euboica till now are regarded here as diploid O. heterophylla Griseb. As usual in asterotrichous Onosma with 2n = 14, 26, 28 or 38 in SE Europe, also the three species discussed here can be difficult to distinguish. Our descriptions, the table of characteristics and the figures may help to facilitate accurate determinations.
The term isoholotype is proposed for specimens originating from the same individual as the holotype, but which are preserved in other herbaria than the holotype.