Phylogenetic reconstruction prompts taxonomic changes in <I>Sauropus</I>, <I>Synostemon</I> and <I>Breynia</I> (<I>Phyllanthaceae</I> tribe <I>Phyllantheae</I>)

Abstract

Previous molecular phylogenetic studies indicated expansion of Breynia with inclusion of Sauropus s.str. (excluding Synostemon). The present study adds qualitative and quantitative morphological characters to molecular data to find more resolution and/or higher support for the subgroups within Breynia s.lat. However, the results show that combined molecular and morphological characters provide limited synergy. Morphology confirms and makes the infrageneric groups recognisable within Breynia s.lat. The status of the Sauropus androgynus complex is discussed. Nomenclatural changes of Sauropus species to Breynia are formalised. The genus Synostemon is reinstated.

Historical biogeography of Breynia (Phyllanthaceae): what caused speciation?

“…Here we will follow the nomenclature of van Welzen et al . () in which Breynia and Sauropus are united under Breynia and Synostemon is reinstated. Breynia and Synostemon have their own area of diversification.…”

Reduction of Breynia subgenus Hemisauropus to B. section Cryptogynium and discussion of the B. quadrangularis complex (Phyllanthaceae)

“…It is obvious that Chakrabarty and colleagues prefer to maintain entities in the Breynia quadrangularis complex (sect. Cryptogynium) as distinct species (Chakrabarty & Gangopadhyay 1996, under Sauropus;Chakrabarty & Balakrishnan 2015), while I (Van Welzen 2003Van Welzen et al 2014) regard them as one single, variable species. These species were also partly used as infraspecific entities (var.…”

“…The subgenus Breynia clade splits again in two groups, recognised as section Breynia (equalling the genus Breynia before union with Sauropus) and section Cryptogynium (Müll.Arg.) Welzen & Pruesapan (Van Welzen et al 2014). The infrageneric classification thus reflects the phylogeny.…”

“…Two options exist to address the paraphyly. Phyllanthus can be made monophyletic by either subsuming the non-included genera into a gigantic Phyllanthus (Hoffmann et al 2006) or Phyllanthus may be split into morphologically recognisable monophyletic genera (Van Welzen et al 2014). Van Welzen et al (2014) opt for the latter solution and based on phylogenetic evidence (Pruesapan et al 2012) they recognised the genera Synostemon F.Muell.…”

“…The raise to subgeneric level disrupts the phylogenetic information (Pruesapan et al 2012, Van Welzen et al 2014, because Chakrabarty & Balakrishnan (2015) only retain section Breynia, while section Cryptogynium (their subgenus Hemisauropus) is of equal standing. In their classification it seems that their subgenus Hemisauropus equals subgenus Sauropus and might be a sister-group, which it is not.…”