trnL-F and rpl16 Sequence Data and Dense Taxon Sampling Reveal Monophyly of Unilocular Anthered Gomphrenoideae (Amaranthaceae) and an Improved Picture of Their Internal Relationships

Abstract

The Amaranthaceae-Chenopodiaceae alliance has been the focus of several phylogenetic studies, but major questions concerning the internal relationships of Amaranthaceae still remain unanswered. This study aims to test the monophyly of the subfamily Gomphrenoideae and to examine the generic relationships within this group. Parsimony and Bayesian analyses of trnL-F and rpl16 show that the subfamily Gomphrenoideae is monophyletic. The clade of Gomphrenoideae represents a large and diverse radiation of the Amaranthaceae in the New World. Unilocular anthers are a morphological synapomorphy for Gomphrenoideae that was derived from bilocular anthers. Three major clades are resolved: the Gomphrenoids, the Alternantheroids, and the Iresinoids, which are largely supported by pollen morphology. The Iresinoid clade is sister to Alternantheroids plus Gomphrenoids, rendering metareticulate pollen as the synapomorphy for the latter two clades. Tribes and subtribes delimited by androecium and inflorescence characters are poly- or paraphyletic. Several genera are monophyletic including the large genus Alternanthera, whereas Gomphrena is polyphyletic. Irenella and Woehleria are resolved within Iresine whereas Blutaparon and Lithophila fall within the polyphyletic Gomphrena. The trnL-F and rpl16 sequence data are the most variable chloroplast regions examined to date for the family and are highly effective in resolving relationships in Amaranthaceae.

The metareticulate pollen morphology ofAlternantheraForssk. (Gomphrenoideae, Amaranthaceae) and its taxonomic implications

“…The mesoporia refers to the tectated areas surrounding two sunken pores. This type of pollen sculpture and aperture organisation is synapomorphic for the core gomphrenoid (Kadereit et al 2003;Müller & Borsch 2005a, 2005b and the gomphrenoids+alternantheroids clade (Sánchez-del Pino et al 2009). Borsch (1998) used pollen shape, mesoporia form (flat or vaulted), tectum sculpture and variants of ektexinous bodies (e.g.…”

“…Pollen-specific characters of Amaranthaceae were used according to several other studies (Skvarla & Nowicke 1976;Zandonella & Lecocq 1977;Eliasson 1988;Borsch 1998;Sánchez-del Pino 2001;Sánchez-del Pino et al 2002). We provide a diagram Pollen of Alternanthera (Amaranthaceae) 3 that shows the structures and morphological landmarks of the pollen grains that were observed and measured here ( Figure 1).…”

“…Pore membrane ornamentation as defined by ektexinous bodies in Amaranthaceae is granulate (Livingstone et al 1973;Sánchez-del Pino 2001), with angular ektexinous bodies (Skvarla & Nowicke 1976) or verrucose (Zandonella & Lecocq 1977). Based on SEM, Borsch (1998) described more than five ektexinous body shapes (tooth-shaped, roundish, polyhedrical, triangular, quadrangular), variations in their number and arrangement and number of microspines on ektexinous bodies.…”

“…-Different terms have been applied for this structure; it has been named torus (Sánchez-del Pino 2001 in Tidestromia); Punt et al (1994) referred to it as an annulus or the area of the exine surrounding a pore that is sharply differentiated from the remainder of the exine, either in ornamentation or thickness. In the present work, we adopt Borsch's (1998) flat ring definition; it is the first, most complete and, in our opinion, the best description for differentiating the flanking area of the pollen pore membrane in Amaranthaceae.…”

“…subfamily Gomprenoideae: Sánchez-del Pino et al 2009) and species and infraspecific categories (e.g. Tidestromia: Sánchez-del Pino 2001;Sánchez-del Pino et al 2002;Sánchez-del Pino & Flores Olvera 2006).…”