Further cytogenetical studies on diploid and polyploid species of Eryngium L. (Saniculoideae, Apiaceae) from Argentina

Meiotic studies are carried out in 7 species of Eryngium L. (Saniculoideae, Apiaceae), belonging to both sections Foetida and Panniculata. The chromosome number of E. dorae Norm. (n = 8) (Foetida) is reported for the first time, while the gametic chromosome number of E. nudicaule Lam. (n = 7) (Foetida) and E. eburneum Decne. (n = 8), E. horridum Malme (n = 8), E. megapotamicum Malme (n = 16), E. mesopotamicum Pedersen (n = 24), and E. pandanifolium Cham. et Schlechtd. (n = 24) (all belonging to Panniculata) is confirmed in several natural populations. Whereas in section Foetida all species are diploids and two basic chromosome numbers are present (x = 8 and x = 7), in section Panniculata all species are x = 8 but there are three different ploidy levels (diploid, tetraploid, hexaploid). This study reveals that meiosis in all species is normal, with regular bivalent formation in all studied cells. Furthermore, the pollen stainability is above 80% in all cases. These data, together with the previous karyotype analyses, will contribute to the clarification of the relationships between members of both sections, where different mechanisms of speciation have been postulated.