Abstract: A taxonomic revision of Helichrysum sect. Stoechadina, a section with a Mediterranean distribution, is presented. Taxonomic, nomenclatural, morphological, chromosomal, geographical, and ecological data are provided for each taxon. Eleven taxa are recognized, two lectotypifications are proposed, and a taxonomic key and a sectional description are included. The following new combinations are proposed: Helichrysum italicum subsp. siculum (Jord. & Fourr.) Galbany, L. Saez & Benedi comb. nov. and Helichrysum italicum subsp. picardii (Boiss. & Reut.) Galbany, L. Saez & Benedi comb. nov.
Key words: Asteraceae, Gnaphalieae, endemism, Helichrysum, Mediterranean region, infraspecific variation.
Resume: Les auteurs presentent une revision taxonomique des Helichrysum sect. Stoechadina, incluant toutes les especes avec distribution mediterraneenne. On presente pour chaque taxon des donnees sur la taxonomie, la nomenclature, la morphologie, les chromosomes, la geographie et l'ecologie. On reconnait 11 taxons, on propose deux lectotypifications et une cle taxonomique, ainsi qu'une description de la section. On propose les combinaisons nouvelles suivantes : Helichrysum italicum subsp. Siculum (Jord. & Fourr.) Galbany, L. Saez & Benedi comb. nov. et Helichrysum italicum subsp. picardii (Boiss. & Reut.) Galbany, L. Saez & Benedi comb. nov.
Mots cles: Asteraceae, Gnaphalieae, endemisme, Helichrysum, region mediterraneenne, variation intraspecifique.
[Traduit par la Redaction]
Introduction
The genus Helichrysum Mill. (Gnaphalieae) is distributed throughout the African continent, Madagascar, the Mediterranean basin, Macaronesia, central Asia, and India (Anderberg 1991), and comprises ca. 500 (Hilliard 1983) to ca. 600 (Anderberg 1991) species. The only exhaustive infrageneric classification of the entire genus is that provided by de Candolle (1838). However, de Candolle's classification did not always reflect natural phylogenetic relationships among species, and several more species have since been described. The Mediterranean, European, western Asian, and central Asian Helichrysum species are morphologically characterized as having the following characters: homogamous or heterogamous capitula, with hermaphroditic flowers outnumbering the pistillate ones; phyllaries with a fenestrated stereome; smooth or alveolate receptacle; cypselae glabrous or with duplex hairs; monomorphic uniseriate pappus, consisting of several free scabrid bristles, with patent cilia at the base. Our previous phylogenetic studies on this genus based on ITS sequences (Galbany-Casals et al. 2004a) showed this group to be monophyletic and derived from African ancestors, findings supported by the fact that they constitute a rather uniform group with regards to the gross morphology of vegetative characters, as well as most of the reproductive character morphology. The only exception was that two species, Helichrysum frigidum (Labill.) Willd. and H. montelinasanum Schmid, appeared grouped with the outgroups in the phylogenetic tree obtained, not within the Mediterranean Helichrysum clade nor the main Helichrysum clade. Following a detailed study based on morphological traits, these two species were tranferred to a new genus, Castroviejoa Galbany, L. Saez & Benedi: Castroviejoa frigida (Labill.) Galbany, L. Saez & Benedi and Castroviejoa montelinasana (Schmid) Galbany, L. Saez & Benedi (Galbany-Casals et al. 2004b, 2004c).
The Mediterranean, European, western Asian and central Asian Helichrysum species have been classified into two main groups (see Table 1 for main infrageneric classifications), which in the latest treatment (Clapham 1976) are recognised at...