The genus Adenodaphne is currently considered endemic to New Caledonia, but its distinction from Litsea is questionable based on morphological similarity. An earlier phylogenetic analysis (ITS) including one species of Adenodaphne and two Asian species of Litsea did support their close relationship but did not permit resolution of their generic boundary. We sampled the four species of Adenodaphne currently recognized (11 accessions) and 11 of the 13 endemic species of Litsea currently recognized, plus one undescribed species (24 accessions in total). Based on our extensive herbarium studies, field work, and especially our molecular phylogenetic analyses (ITS) we conclude that Adenodaphne is not distinct from Litsea and that all species of Adenodaphne should be recognized within Litsea, thereby necessitating the creation of two new species synonymies and one nomen novum. As well, Litsea paoueensis is here synonymized with L. deplanchei.

In this study we generated internal transcribed spacer region (ITS) sequence data for 43 new samples (Litsea, 31; Adenodaphne, 11; Actinodaphne, 1). We selected the ITS region as it has been successfully used across the Lauraceae at different taxonomic levels (Chanderbali et al. 2001; Jian-Feng et al. 2016; Li et al. 2004; Li et al. 2008; Li et al. 2011; Liu et al. 2013; Rohde et al. 2017), and provides the highest level of resolution at the species level (China Plant Bol Group et al. 2011; Liu et al. 2017).

Thirty-three samples were collected in New Caledonia, six during an expedition in Papua New Guinea (see Munzinger et al. 2020), one in New Zealand, and one in Wallis and Futuna. The New Caledonian samples represent the four species of Adenodaphne accepted by Kostermans in the Flore as well as eleven of the thirteen Litsea species that he considered there, plus two individuals from Ouaième, that we could not relate to any Litsea or Adenodaphne species described. We also included ITS sequences from GenBank from published studies that included vouchered specimens, among them that of the type species for the genus Litsea, L. glutinosa (Lour.) C.B.Rob. We did not include Litsea paoueensis, known only from the type Hürlimann 1158, or Litsea imbricata Guillaumin (known only from two collections), both of which we searched for in the field in vain. As well, we excluded L. mackeei Kosterm., which Kostermans (1977) described 3 years after the publication of his treatment in the Flore, as it belongs to the Oleaceae (Munzinger and McPherson 2017). All taxa are listed in Table 1, which includes the code of the herbarium (sensu Thiers 2021) where the vouchers are deposited.

All samples included in this study are vouchered. Please acknowledge the collector and collector number when using these samples.