How many of Cassini anagrams should there be? Molecular systematics and phylogenetic relationships in the Filago group (Asteraceae, Gnaphalieae), with special focus on the genus Filago

Abstract

The Filago group (Asteraceae, Gnaphalieae) comprises eleven genera, mainly distributed in Eurasia, northern Africa and northern America: Ancistrocarphus, Bombycilaena, Chamaepus, Cymbolaena, Evacidium, Evax, Filago, Logfia, Micropus, Psilocarphus and Stylocline. The main morphological character that defines the group is that the receptacular paleae subtend, and more or less enclose, the female florets. The aims of this work are, with the use of three chloroplast DNA regions (rpl32‐trnL intergenic spacer, trnL intron, and trnL‐trnF intergenic spacer) and two nuclear DNA regions (ITS, ETS), to test whether the Filago group is monophyletic; to place its members within Gnaphalieae using a broad sampling of the tribe; and to investigate in detail the phylogenetic relationships among the Old World members of the Filago group and provide some new insight into the generic circumscription and infrageneric classification based on natural entities. Our results do not show statistical support for a monophyletic Filago group. The traditional generic circumscription of most of the genera, as well as the traditional infrageneric classification of the genus Filago, do not correlate with the inferred phylogenetic relationships. A monophyletic circumscription of Filago and a new subgeneric treatment for this genus are proposed, this involving description of a new subgenus (Filago subg. Crocidion Andrés‐Sánchez & Galbany, subg. nov.) and four new combinations (Filago subg. Pseudevax (DC.) Andrés‐Sánchez & Galbany, comb. et stat. nov.; Filago discolor (DC.) Andrés‐Sánchez & Galbany, comb. nov.; Filago gaditana (Pau) Andrés‐Sánchez & Galbany, comb. et stat. nov. and Filago griffithii (A. Gray) Andrés‐Sánchez & Galbany, comb. nov.). The genera Cymbolaena, Evacidium and Evax are synonymised under Filago. Several incongruences found between chloroplast and nuclear DNA sequence analyses, as well as a notable degree of intraspecific sequence variation in all regions sequenced are documented and discussed.

Molecular phylogeny of the ‘Cape snow’ genus Syncarpha (Asteraceae: Gnaphalieae) reveals a need for generic re-delimitation

“…Within the Gnaphalieae crown radiation we recover both the HAP and FLAG clades identified by previous authors (Smissen et al, 2011;Galbany-Casals et al, 2010). Despite sparse sampling of the HAP clade, our data corroborates that of Bergh et al (2011) …”

“…However, in all these studies the branch lengths subtending these nodes are short and in some cases support values are low, indicating that speciation events occurred in rapid succession and that the true branching order may be difficult to discern. Our analysis supports an alternative arrangement, also retrieved by Galbany-Casals et al (2010; although they did not include any members of the Stoebe clade) and Bengston et al (2011), in which the Stoebe, Ifloga, and Metalasia clades form a monophyletic group (the SIM clade) that is recovered (though not supported) as sister to the 'rest of Gnaphalieae', hereafter re-named the 'crown radiation' (node B, Fig. 2).…”

“…Sister to these (PP = 1.00, BS = 73%) is a clade comprising Vellereophyton dealbatum and Lasiopogon debilis (PP = 1.00; BS = 90%). The sampled representatives of the Filago-Leontopodium-Antennaria-Gamochaeta (FLAG) clade (sensu Galbany-Casals et al, 2010) are monophyletic in our analysis (PP = 1.00; BS = 82) and placed sister to the VellereophytonLasiopogon + Australasian + Edmondia + Syncarpha 1 clade in the MCC tree, but with no support. The Syncarpha 2 clade (PP = 1.00; BS = 100%), comprising S. sordescens, S. striata, S. recurvata, S. chlorochrysum, S. mucronata and S. paniculata is sister to Gnaphalium austroafricanum (PP = 0.95; BS = 75%), the whole in turn being resolved as sister to Plecostachys (node 'C' in Fig.…”

“…2). Our crown radiation is thus the same as the clade so named by Galbany-Casals et al, 2010, and comprises all of Gnaphalieae, excluding the Relhania clade and also excluding the SIM lineages. There are several morphological synapomorphies that support the hypothesis that the SIM clade shares a common ancestor.…”

“…Although Syncarpha has been included in a number of studies exploring phylogenetic relationships within the tribe Gnaphalieae (Bayer et al, 2000;Bergh and Linder, 2009;Galbany-Casals et al, 2010Bergh et al, 2011) these studies have consistently each sampled only a single species of Syncarpha. Thus, while it is now evident that Syncarpha is nested within the "crown radiation" of Gnaphalieae (Ward et al, 2009), it remains unknown whether the genus is monophyletic and, therefore, best treated in a single revision.…”