Eriostemon, Sm.

Duretto, Marco F., Heslewood, Margaret M. & Bayly, Michael J., 2023, Generic and infrageneric limits of Phebalium and its allies (Rutaceae: Zanthoxyloideae), Australian Systematic Botany 36 (2), pp. 107-142 : 133

Eriostemon , Philotheca and their relatives ( Crowea , Drummondita , Geleznowia , Muiriantha )

The large genus Philotheca is represented here by 18 species (of ~55 total) and all four sections were included in this study. Closely related genera are also well represented in this study, including Eriostemon (both species sampled), Crowea (all three species sampled), Drummondita (3 of 10 species sampled), Geleznowia (1 of 2 species sampled), and Muiriantha (monotypic, sampled). Philotheca is polyphyletic ( Fig. 1 , 2 , S 1 , S 2 ), confirming results presented by Bayly et al. (2013), Duretto et al. (2020) and Appelhans et al. (2021), although those analyses included fewer species. Each of the four sections was monophyletic and there was strong to robust support for each of the following relationships: species of P. section Philotheca in a clade with Geleznowia and Drummondita (1.00 PP, 100% JK); that clade being sister to P. section Erionema with strong support (1.00 PP, 99% JK); P. section Cyanochlamys (F.Muell.) F.Muell. being sister to the monotypic Muiriantha (1.00 PP, 100% JK); and P. section Corynonema grouping with Eriostemon and Crowea in the combined analyses with more modest support (0.99 PP). Wilson (1998 a) discussed the relationships among the sections and noted that P. section Philotheca is similar to Geleznowia in seed morphology. Of note is the clear split between the south-western Australian species of Crowea from the clade containing both south-eastern Australian species. With further study, Crowea may require further division. On the basis of the single exemplars in our molecular analyses, the specific status of C. saligna Andrews is open to question, being embedded within the C. exalata F.Muell. clade with three sampled subspecies. The entire Philotheca assemblage is polyphyletic and the relationships recovered among the larger clades differ between analyses. Philotheca and its relationships are part of another study (see e.g. Batty et al. 2022), with greater taxon sampling and using whole plastid sequences ( H. Orel, pers. comm.), and will not be discussed in detail further here. Philotheca section Philotheca is also discussed under Pollination below.

Figures

Fig. 1. Simplified version of the Bayesian 50% majority-rule consensus tree of combined molecular data, with thick lines showing supported clades (≥0.95 PP). Genera have been collapsed on the basis of sampling density, to provide a snapshot of the overall relationships.

Fig. 2. (Caption on next page)