Abstract
La clasificación genérica de varios miembros de la tribu Gnaphalieae (Compositae) y en particular la delimitación genérica del antiguo género Gnaphalium ha sido problemática durante mucho tiempo. El género Pseudognaphalium fue escindido de Gnaphalium por su morfología lo que después fue apoyado por filogenias moleculares. Sin embargo, la identidad genérica de algunas especies todavía es dudosa. Aquí aportamos un estudio morfológico de Pseudognaphalium aldunateoides, que es comparado con las especies tipo de los géneros Gnaphalium (Gnaphalium uliginosum) y Pseudognaphalium (Gnaphalium oxyphyllum). También hemos incluido estas tres especies en filogenias moleculares de la tribu Gnaphalieae basadas en ADN ribosómico nuclear y ADN cloroplástico. Nuestros resultados muestran que P. aldunateoides tiene el vilano dimórfico, carácter que no está presente en el género Pseudognaphalium pero que, sin embargo, es característico del género Gnaphalium. Además, su estereoma muestra características intermedias entre el estereoma no dividido típico del género Gnaphalium y el estereoma fenestrado típico del género Pseudognaphalium. En ambas filogenias, P. aldunateoides se sitúa dentro del clado Gnaphalium s. str., no próximamente emparentado con Pseudognaphalium. Con todas estas evidencias concluimos que P. aldunateoides se clasifica correctamente dentro de Gnaphalium.
Highlights
It has long been known that generic classification of some genera of the tribe Gnaphalieae (Asteraceae) is problematic, specially involving the large and heterogeneous Helichrysum Mill. and Gnaphalium L., as well as some other related genera such as Pseudognaphalium Kirp. (Hilliard & Burtt, 1981; Anderberg, 1991; Galbany-Casals et al, 2014). Hilliard & Burtt (1981) made important advances in establishing new generic delimitations based on a critical and detailed morphological study of most controversial genera in Gnaphalieae
The nrDNA (Fig. 2) and cpDNA (Fig. 3) phylogenetic trees placed the genus Pseudognaphalium within the HAP clade, being part of the clade mainly constituted by the paraphyletic genus Helichrysum, which is in conformity with previous studies (Smissen et al, 2011; Galbany-Casals et al, 2014; Nie et al, 2016)
While the nrDNA phylogeny showed Pseudognaphalium to be constituted by two well-supported and independent clades (Fig. 2, clades A.1 and A.2), cpDNA showed it to be constituted by three independent lineages (Fig. 3, clades A.1, A.2 and A.3)
Summary
It has long been known that generic classification of some genera of the tribe Gnaphalieae (Asteraceae) is problematic, specially involving the large and heterogeneous Helichrysum Mill. and Gnaphalium L., as well as some other related genera such as Pseudognaphalium Kirp. (Hilliard & Burtt, 1981; Anderberg, 1991; Galbany-Casals et al, 2014). Hilliard & Burtt (1981) made important advances in establishing new generic delimitations based on a critical and detailed morphological study of most controversial genera in Gnaphalieae. Hilliard & Burtt (1981) made important advances in establishing new generic delimitations based on a critical and detailed morphological study of most controversial genera in Gnaphalieae. In their work, they proved the value of two features, among others: the nature of the stereome of involucral bracts and of the pappus. In other genera, the stereome may be fenestrated, i.e. some distinct vascular strands lie in a translucent area of unthickened cells sharply distinguishable from the thickened cells of the rest of the stereome (Hilliard & Burtt, 1981)
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