Leontodon, sensu Widder, 1975

Zidorn, Neela Enke Birgit Gemeinholzer Christian, 2012, Molecular and phytochemical systematics of the subtribe Hypochaeridinae (Asteraceae, Cichorieae), Organisms Diversity & Evolution (New York, N. Y.) 12 (1), pp. 1-16 : 9-10

Leontodon

The genus Leontodon s.l. Widder (1975) is scattered among three well supported clades: the first clade includes the genus Hedypnois (type species: Hedypnois rhagadioloides ) and Leontodon sections Asterothrix and Leontodon and thus also the type species of the genus, Leontodon hispidus L.; the second clade comprises only Leontodon section Thrincia ; and third only the genus Scorzoneroides (former Leontodon sections Kalbfussia and Oporinia ). Due to the fact that the other Leontodon sections are related more closely to the genera Helminthotheca , Hypochaeris , Picris , and Robertia than to Scorzoneroides , Scorzoneroides has to be classified as a genus distinct from Leontodon as already proposed by Samuel et al. (2006). Nomenclatural consequences for species from the Euro-Mediterranean were drawn by Greuter et al. (2006). The separation of Scorzoneroides is also supported by cytological evidence as the prevailing basic chromosome number is x 0 5 ( Fig. 1 )—a number so far not reported from Leontodon species.

Leontodon boryi , L. rosani , and L. villarsii constitute the sister clade to Hedypnois and L. siculus ( Fig. 1 ). These species are presumably of hybrid origin—a hypothesis supported by their intermediate position (with respect to their supposed parental species) in the phylogeny as well as by their aberrant karyotype ( Samuel et al. 2006). The species of Leontodon section Asterothrix have 2 n 0 8 chromosomes, the species of Leontodon section Leontodon 2 n 0 14. Hedypnois rhagadioloides forms a polymorphic complex with varying chromosome numbers (2 n 0 8, 11, 12, 13, 14, 16; Nordenstam 1971; Carr et al. 1999). Leontodon boryi and L. villarsii have a chromosome number of x 0 7, whereas L. rosani has a chromosome number of x 0 11 ( Lippi and Garbari 2004; Samuel et al. 2006; Fig. 1 ). The former two taxa could result from two ancestral taxa with 2 n 0 14 ( Samuel et al. 2006). Leontodon rosani is thought to have originated from an L. villarsii -like ancestor (x 0 7) and a member of Leontodon section Asterothrix (x 0 4) ( Pittoni 1974; Samuel et al. 2006). However, an ancestor from Hedypnois instead of a parent from either former Leontodon section Asterothrix (x 0 4) or former Leontodon section Leontodon (x 0 7) is also a possibility as some Hedypnois taxa can possess either x 0 4 or x 0 7.

As Leontodon section Leontodon is paraphyletic in its current circumscription, we propose to incorporate Leontodon section Asterothrix as well as the former genus Hedypnois into Leontodon section Leontodon , which is then well supported (100/99/1.00, Figs. 1 , 2 )

The species found in the clade Thrincia all belong to Leontodon section Thrincia sensu Widder (1975) and share the basic chromosome number x 0 4 ( Fig. 1 ). Stebbins et al. (1953) assumed a trend towards a reduction of chromosome numbers within the tribe Cichorieae (also see Babcock 1947a, 1947b). Therefore, section Thrincia was considered to be derived within Leontodon s.l. due to its low chromosome number (x 0 4; Izuzquiza and Feliner 1991). Molecular and karyological studies in other genera of the Cichorieae suggest that chromosome number reductions as well as increases can coexist within one genus (e.g. Crepis ; Enke and Gemeinholzer 2008; Enke et al. 2011) and are therefore not always suitable to infer phylogenetic relationships. The question of whether Thrincia , as part of the sister group of the clade encompassing Hedypnois and Leontodon sections Asterothrix and Leontodon , constitutes a separate genus or a section of Leontodon needs further investigation.

Figures

Fig. 1 Maximum likelihood (ML) phylogram. Bootstrap support values of ML and posterior probabilities of the Bayesian Likelihood (BL) analysis are given above branches (ML/BL). H I and H II denote clades

Fig. 2 Maximum parsimony (MP) 50% majority rule consensus tree. Bootstrap support values given above branches. Clades contain species according to Fig. 1