# Phylogenetic placement of the mysterious Malagasy genus Ambrella H. Perrier (Vandeae, Orchidaceae)

## TL;DR

This study clarifies the evolutionary position of the enigmatic orchid genus Ambrella in Madagascar, revealing its close relatives and divergence timing.

## Contribution

The study provides a resolved phylogenetic placement and divergence timing for Ambrella within the Vandeae orchid tribe.

## Key findings

- Ambrella forms a strongly supported clade with Cryptopus, Oeonia, and Neobathiea.
- Ambrella diverged during the Late Miocene to Early Pliocene (ca. 8.8–3.3 Mya).
- Ambrella retains distinct morphological traits despite its phylogenetic proximity to other genera.

## Abstract

The monotypic genus Ambrella H. Perrier, endemic to Madagascar and traditionally placed within the subtribe Angraecinae, has long poses a challenge in terms of its phylogenetic classification.

To clarify the evolutionary position of Ambrella, analyzed nuclear (ITS) and plastid (matK) markers applying maximum likelihood methods for phylogenetic inference and estimating divergence times using a Bayesian relaxed molecular clock model implemented in BEAST.

Our results show that Ambrella forms a strongly supported clade with the Malagasy genera Cryptopus Lindl., Oeonia Lindl., and Neobathiea Schltr. Despite the phylogenetic proximity, Ambrella remains morphologically distinct, particularly in terms of its floral architecture. According to molecular dating, the lineage leading to Ambrella diverged during the Late Miocene to Early Pliocene (ca. 8.8–3.3 Mya), a period of substantial ecological change in Madagascar.

The results of this study provide new insight into the evolutionary history of Ambrella and clarify its phylogenetic position within Vandeae. Despite forming a well-supported clade with other Malagasy genera such as Cryptopus, Oeonia, and Neobathiea, Ambrella maintains clear morphological distinctiveness, particularly in its floral architecture. This suggests that its most striking morphological features may have evolved independently.