Philotheca glasshousiensis

Batty, Erin L., Holmes, Gareth D., Murphy, Daniel J., Forster, Paul I., Neal, Will C. & Bayly, Michael J., 2022, Phylogeny, classification and biogeography of Philotheca sect. Erionema (Rutaceae) based on nrDNA sequences, Australian Systematic Botany 35 (4), pp. 326-338 : 336

Polyphyly of Philotheca glasshousiensis

The polyphyly of P. glasshousiensis provides strong evidence that northern and southern populations should be recognised as two distinct species. The southern populations, from the Glasshouse Mountains and Mount Cooroora, represent P. glasshousiensis sensu stricto, the type being from the Glasshouse Mountains (Mount Coonowrin). These southern populations are most closely related to but clearly distinct from P. queenslandica , being separated by long branches on the phylogenetic tree ( Fig. 2 ). Although these two species both occur in south-eastern Qld, there is a clear ecological separation between them, with P. glasshousiensis growing in rocky areas towards the summits of the mountains and P. queenslandica restricted to lowland heaths in wallum vegetation that is periodically inundated.

Herbarium specimens from the northern populations, at Cania Gorge (not sequenced here) and Kroombit Tops, were included in the circumscription of P. glasshousiensis (or P. myoporoides subsp. leichhardtii (Benth.) Paul G. Wilson ) by Bayly (1998) and Forster (2005) on the basis of morphological resemblance and their occurrence in similar cliff line habitat. Our recent, preliminary comparisons indicate that, although the northern populations resemble P. glasshousiensis sensu stricto in most qualitative features (many of which are highly conserved across sect. Erionema), they usually have larger leaves than those of P. glasshousiensis sensu stricto but there is overlap in leaf sizes. More detailed study is needed to clarify the extent to which the two genetic groups can be distinguished morphologically.

Figures

Fig. 2. Majority rule consensus tree based on BI analysis of combined ITS and ETS dataset, showing mean branch lengths. Bayesian posterior probabilities are shown (either first, or above branches) along with MP bootstrap values (either second or below branches; only shown where bootstrap support is>50%). Dashed branches were not present on the MP strict consensus tree.