Boronia humifusa

Duretto, Marco F., Heslewood, Margaret M. & Bayly, Michael J., 2023, A molecular phylogeny of Boronia (Rutaceae): placement of enigmatic taxa and a revised infrageneric classification, Australian Systematic Botany 36 (2), pp. 81-106 : 97

Placement of Boronia humifusa , B. ovata , B. scabra and B. series Ovatae

Boronia humifusa , B. ovata and B. scabra (all from SW Austr.) form a robustly supported clade that is clearly separated from section Boronia , confirming the conclusions of Bayly et al. (2015). Series Ovatae was described by Wilson (1971) under section Imbricatae to accommodate B. ovata and B. scabra , although later, when reviewing the genus, Wilson (1998) included the series as a synonym of a broadly defined series Boronia . Boronia humifusa was described by Wilson (1998) who noted the species was distinct in series Boronia (equivalent to the section Boronia of Bayly et al. 2015) in having petals with only one medial vein and lacking an apiculum on the abaxial surface, as well as a unique seed type. Boronia humifusa , B. ovata and B. scabra form a strongly supported clade with B. humifusa , sister to a clade containing the other two species, and all species are separated by long branches. This clade is possibly sister to a clade comprising section Boronia ( Fig. 1 ), although this relationship is not supported in the separate analyses, and so warrants a similar rank. All three species have simple leaves, terminal inflorescences and seeds that are smooth or minutely tuberculate with a dorsal hilum that may or may not be in a shallow groove ( Wilson 1971, 1998; Choi et al. 2012; Duretto et al. 2013). These three characteristics could be morphological synapomorphies for the group, although they are homoplasious characters in Boronia . Series Ovatae is raised to the rank of a section below (see Taxonomy).

Figures

Fig. 1. Bayesian 50% majority-rule consensus tree from the combined analysis of two nuclear (ITS, ETS) and three plastid markers (psbA–trnH, trnL–trnF and rbcL), with thick lines showing supported clades (≥0.95 PP). Jackknife percentages from MP analysis are indicated with symbols above branches: 100% JK (closed triangle); 90–99% JK (closed circle); 75–89% JK (open triangle); 50–74% JK (open circle). New or revised sectional assignments are indicated in bold. Section Boronia clade has been collapsed and is shown in detail in Fig. 2.