Phylogenetic studies in the Hoya group (Apocynaceae, Marsdenieae): the position of Anatropanthus and Oreosparte

Michele Rodda,Tatyana Livshultz,Sri Rahayu,Enrico Ercole,Gillian Khew,Matti Niissalo,Nadhanielle Simonsson

doi:10.3372/wi.50.50112

Abstract

Recent molecular phylogenetic studies have shown that Hoya is paraphyletic without Absolmsia, Clemensiella, Madangia, and Micholitzia. These genera have been placed in synonymy with Hoya, but the monophyly of Hoya sensu lato relative to other genera of the broader Hoya group (Dischidia, Anatropanthus and Oreosparte, the latter two never included in a molecular phylogenetic analysis) remained unclear. Furthermore, no analysis has included both a significant sample of the Hoya group and outgroup genera of Marsdenieae to test the monophyly of the Hoya group and its position within the tribe. To address these gaps, we assembled two data sets: (1) the chloroplast trnT-trnL-trnF locus from 110 species and (2) three chloroplast loci (trnT-trnL-trnF, atpB-psbA spacer and matK) and two nuclear loci (nrDNA ITS and ETS) from 54 species. The Hoya group is monophyletic and nested in an Asian/Australian clade of Marsdenia s.l. The genus Hoya is paraphyletic unless Anatropanthus, Dischidia and Oreosparte are included. However, current evidence is not sufficient to synonymize Dischidia and Oreosparte with Hoya. Support for synonymy of Anatropanthus with Hoya is strong and the new name H. insularis is proposed. A clade of three new species with Oreosparte-like morphology is sister to the rest of the Hoya group and is described as the new genus Papuahoya.Citation: Rodda M., Simonsson N., Ercole E., Khew G., Niissalo M., Rahayu S. & Livshultz T. 2020: Phylogenetic studies in the Hoya group (Apocynaceae, Marsdenieae): the position of Anatropanthus and Oreosparte. – Willdenowia 50: 119–138. doi: https://doi.org/10.3372/wi.50.50112Version of record first published online on 27 March 2020 ahead of inclusion in April 2020 issue.

Highlights

We excluded the species of Periplocoi deae, which are only distantly related to Asclepiadoideae (Straub & al. 2014), the single unidentified Marsdenia species, and the Hoya group species, and added 54 species of Marsdenieae, primarily of the Hoya group, and a sample of Vincetoxicum flexuosum
Sequencing — In total 227 new sequences were generated for this study (Appendix 1 in Supplemental Content online), including 15 from species previously sampled by Wanntorp & al. (2014), two from Hoya corymbosa Rodda & Simonsson, previously sampled in Rodda & al. (2013), two from H. papaschonii Rodda, previously sampled in Rodda & Ercole (2014), and 209 from 34 newly sampled species
The only moderately to strongly supported incongruence between chloroplast and nuclear loci concerns the position of Dischidia milnei Hemsl., which was supported as sister to D. major (Vahl) Merr. by the cp loci (ML BS 90 ) versus sister to the rest of the ant-house-leaved Dischidia species by the nuclear loci (ML BS 97)

Summary

Introduction

(Fig. 1A, B) (Marsdenieae, Asclepiadoi deae) is the largest genus in Apocynaceae, comprising 350 – 450 species of Asian and Australasian succulent epiphytic and terrestrial vines and shrubs (Rodda 2015) that are highly prized horticulturally for their showy “wax” flowers. The flowers of Hoya are characterized by the presence of a staminal corona with the proximal (apical) part of the lobe entire, distal (basal) part of the lobe with an “anther skirt” and revolute margins containing nectaries. The anther guide rails lack inner edges and the pollinia have a pellucid margin along the outer edge The Hoya group — Hoya has been associated with a number of smaller genera including Absolmsia Kuntze (1 sp.), Anatropanthus Schltr. (1 sp.) (Fig. 2), Clemen siella Schltr.

Methods

Results

Discussion

Conclusion