Phylogeny of Impatiens (Balsaminaceae): integrating molecular and morphological evidence into a new classification

Abstract

Impatiens L. is one of the largest angiosperm genera, containing over 1000 species, and is notorious for its taxonomic difficulty. Here, we present, to our knowledge, the most comprehensive phylogenetic analysis of the genus to date based on a total evidence approach. Forty-six morphological characters, mainly obtained from our own investigations, are combined with sequence data from three genetic regions, including nuclear ribosomal ITS and plastid atpB-rbcL and trnL-F. We include 150 Impatiens species representing all clades recovered by previous phylogenetic analyses as well as three outgroups. Maximum-parsimony and Bayesian inference methods were used to infer phylogenetic relationships. Our analyses concur with previous studies, but in most cases provide stronger support. Impatiens splits into two major clades. For the first time, we report that species with three-colpate pollen and four carpels form a monophyletic group (clade I). Within clade II, seven well-supported subclades are recognized. Within this phylogenetic framework, character evolution is reconstructed, and diagnostic morphological characters for different clades and subclades are identified and discussed. Based on both morphological and molecular evidence, a new classification outline is presented, in which Impatiens is divided into two subgenera, subgen. Clavicarpa and subgen. Impatiens; the latter is further subdivided into seven sections.

Three new species of Impatiens (Balsaminaceae) from Myanmar

“…Impatiens sect. Uniflorae (Yu et al 2015) (Fig. 7) and closely related to the Burmese species I. florulenta and I. decurva rather than to the species it resembles most closely in morphological characters, i.e., I. patula from Thailand.…”

“…Impatiens L. (Yu et al 2015: 13). The latter is further divided into seven sections (Yu et al 2015). Of these, sect.…”

“…Uniflorae Hook. f. & Thomson (1860: 113) is characterized by a 5-locular ovary and a short fusiform capsule (Yu et al 2015).…”

“…Based on these studies, we discovered three new species, all of which are described here. We place the species within the infrageneric classification of Yu et al (2015) by using comparative morphology and molecular phylogenetics. similar species was selected for comparative analyses.…”

Impatiens tanintharyiensis (Balsaminaceae), a new species from Southern Myanmar

“…Fischer & Rahelivololona 2007a, 2007b, Suksathan & Triboun 2009, Pusalkar & Singh 2010, Janssens et al 2010, Shui et al 2011, Bhaskar 2012, Utami 2012, Souvannakhoummane & Suksathan 2015, Yu et al 2015. The availability of detailed regional taxonomic studies of Impatiens is unevenly distributed, and some areas have received remarkably little attention, despite their promising geography in relation to Impatiens diversity.…”