Abstract Detail


Hinojosa-Espinosa, Oscar [1], Potter, Daniel [2].

Phylogeny of the Adenophyllum-Thymophylla clade (Tageteae, Asteraceae).

Adenophyllum and Thymophylla are members of the marigold tribe: Tageteae, within the Asteraceae family. Most members of the tribe (the core Tageteae), bear pellucid oil glands in the leaves and/or involucral bracts. Some species of both Adenophyllum and Thymophylla are used in folk medicine or as ornamentals; others are weedy, and several are narrow endemics. In a previous molecular phylogenetic study of the tribe by Loockerman et al. (2002), the genera Adenophyllum and Thymophylla were recovered as monophyletic, and in most analyses the two genera were nested in the same clade, here referred as the Adenophyllum-Thymophylla clade. However, few species of these two genera were sampled in the analysis. This research aims to investigate further the phylogenetic relationships of this clade and closely related genera within the Tageteae. Field work has been done to collect fresh leaf samples of most taxa. Sampling from herbarium specimens has also been carried out. ITS sequences were determined for most species of Adenophyllum and Thymophylla, as well as for some related genera. Additional sequences were downloaded from Genbank and combined with the newly generated data, the resulting data matrix was subjected to a phylogenetic analysis using Bayesian inference. Adenophyllum was recovered as polyphyletic, although most species were nested in a clade with Dysodiopsis as sister. Two species of Adenophyllum formed an earlier diverging clade with Boeberastrum. Thymophylla was monophyletic, but Strotheria was nested within it, and another species of Adenophyllum was recovered as its sister. All these results were supported by posterior probabilities of 0.99-1.0. The results suggest the need to modify the circumscription of Adenophyllum and Thymophylla to make them monophyletic. Two species of Adenophyllum might be transferred to Boeberastrum, and a new monotypic genus might be erected to account for the isolated A. squamosum. Similarly, Strotheria should be transferred to Thymophylla. It is also desirable to implement additional phylogenetic analyses with other molecular markers, especially plastid genome sequences, to see whether they corroborate these results or not. However, ongoing preliminary analysis using the trnL-trnF intergenic chloroplast spacer seem to at least support the polyphyletic nature of Adenophyllum. Advances in the systematics of these genera will likely improve our ability to conserve endemic species, monitor weeds, and use the potential resources (ornamentals, medicinal plants) that these taxa may represent.

1 - University Of California Davis, 909 Arnold St, Davis, CA, 95618, United States
2 - University Of California, Plant Sciences Mail Stop 2, 1 Shields Avenue, Davis, CA, 95616.0, United States

Marigold tribe
Core Tageteae.

Presentation Type: Oral Paper
Session: SYS1, Systematics I: Asterids I & II
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 11:30 AM
Number: SYS1007
Abstract ID:531
Candidate for Awards:None

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