Evolution of secondary heads in Nassauviinae (Asteraceae, Mutisieae)

Abstract

The evolution of the inflorescence head in Asteraceae is important in the diversification of this largest angiosperm family. The aggregation of heads into higher-order capitulescences (secondary heads or syncephalia) is considered evolutionarily advanced. The genera Moscharia, Nassauvia, Polyachyrus, and Triptilion of the subtribe Nassauviinae (Mutisieae) have syncephalia with differing degrees of capitula condensation. ITS and plastid trnL-trnF regions were analyzed separately and together using maximum parsimony and maximum likelihood to examine the evolution of syncephalia in the Nassauviinae. The four genera displaying syncephalia do not form a clade minus taxa without syncephalia, indicating that secondary heads in Nassauviinae have either convergently evolved twice in the subtribe (or, very unlikely) once with multiple reversions. Strong support was obtained for a sister relationship between Leucheria (without syncephalium) and Polyachyrus, and both sister to Moscharia. Nassauvia and Triptilion form a distinct clade but are sister to other genera, Perezia and Panphalea, without syncephalium. Previous hypotheses postulated the evolution from simple to more complex secondary heads. We show that the ancestor of Moscharia, Polyachyrus, and Leucheria, in a more arid habitat, had a complex type of secondary head, and loss of complexity occurred in response to a shift from arid to mesic conditions.

Phylogenetic insights into Andean plant diversification

“…Malesherbia (Malesherbiaceae), where Gengler-Nowak (2002) argued for Pleistocene or even Holocene floristic exchanges. Phylogenetic and biogeographical analyses of the allied genera Polyachyrus, Moscharia and Oxyphyllum (Asteraceae; Katinas and Crisci, 2000;Katinas et al, 2008;Luebert et al, 2009) would also suggest this pattern, with Pleistocene southwards colonizations from the Central Andes to central Chile, but no dating analysis is available for these groups.…”

Una nueva especie de Leucheria (Asteraceae), endémica de Chile.

“…Además, la mayoría de las especies de Leucheria presenta una característica única en la tribu Nassauvieae que es la curiosa disposición de las filarias más internas del involucro como si fueran páleas del receptáculo (Crisci, 1976;Katinas et al, 2008b). Estas filarias varían su orientación sobre el receptáculo rodeando a las flores del margen, ya sea con la cara cóncava hacia el centro del capítulo, con la cara cóncava hacia el exterior del capítulo, o dispuestas en forma perpendicular al centro del capítulo.…”

A New Species of Leucheria (Asteraceae, Mutisieae) from Chile

“…The pollen grains of Leucheria are of the Oxyphyllum Philippi pollen type, with the ectosexine and endosexine of the same thickness, separated by a thin internal tectum in zigzag, a characteristic shared with the genera Nassauvia Commerson ex Jussieu, Triptilion Ruiz & Pavón, and Polyachyrus Lagasca (Crisci, 1974). Recent molecular studies (Katinas et al, 2008) show a sister relationship between Leucheria and Polyachyrus, and both are sister of Moscharia Ruiz & Pavón.…”