Phylogenetic analysis of the Neotropical genus Mezilaurus and reestablishment of Clinostemon (Lauraceae)

Abstract

The delimitation of the genus Mezilaurus (Lauraceae) has always been controversial and depended on the weight given to some characters over others. This study is the first molecular phylogeny of Mezilaurus. It aims to test the monophyly of the genus and its relationships within the Mezilaurus group or other closely related genera. The Mezilaurus group had emerged as monophyletic in previous phylogenetic studies, and includes Anaueria, Chlorocardium, Mezilaurus, Sextonia, and Williamodendron. The phylogenetic analysis of Mezilaurus and related genera was based on trnH–psbA and ITS of ten species of Mezilaurus and thirteen outgroup species. Maximum parsimony and Bayesian inference were performed for each marker separately and for combined datasets. The combined analyses confirmed the monophyly of the Mezilaurus group, but did not support sister relationships of Anaueria and Chlorocardium. The Mezilauroids, containing Mezilaurus, Sextonia, and Williamodendron, formed a well–supported clade. However, the genus Mezilaurus, as currently defined, is not monophyletic and the Mezilaurus mahuba group (Mezilaurus mahuba, M. triunca) emerged as sister to Sextonia. Therefore, we suggest to remove the Mezilaurus mahuba group from Mezilaurus and re–establish it as Clinostemon. Mezilaurus and Clinostemon share rythmic branching with distally clustered leaves, bisexual flowers, three fertile stamens, representing the third androecial whorl, 2–locular anthers and a minute discoid cupule. Clinostemon, however, has stamens with downward recurved anthers and one pair of glands at the base of the filaments, while in Mezilaurus the anthers are erect and glands are absent.

Areas of endemism of Lauraceae: new insights on the biogeographic regionalization of the Espinhaço Range, Brazil

“…Lauraceae include about 50 genera with 2500–3500 species, mostly from tropical areas with only a few species occurring in temperate regions (Rohwer, 1993a). These numbers, however, are obsolete, because of the discovery of new species and the delimitation of new genera (e.g., Alves and Souza, 2013; Trofimov et al., 2016; Rohde, et al., 2017; van der Werff, 2017; Trofimov et al., 2019; Assunção‐Silva et al., 2020), and so a revision of the number of genera and species is needed. The family is primarily represented by shrubs and trees, with an exception being the parasitic twiners of the genus Cassytha L. (Rohwer, 1993a).…”

New insights into the plastome evolution of Lauraceae using herbariomics

“…The Mezilaurus group is monophyletic and consists of six genera including Anaueria , Chlorocardium , Clinostemon , Mezilaurus , Sextonia and Williamodendron [ 2 ]. This group is sister to the core Lauraceae clade according to previous molecular studies based on nuclear and plastid markers [ 2 , 10 , 11 , 19 , 45 ]. Our phylogenomic tree confirms that the Mezilaurus group is monophyletic and the sister relationship of this group to the core Lauraceae clade receives high support (Fig.…”

“…6 , S4 ). However, no synapomorphy has been recorded in morphology and anatomy of the clade to date due to high variability [ 45 , 46 ]. Neither does the plastome structure provide useful taxonomic characters to unite all genera of this group together.…”

A synopsis of Lauraceae (excluding Ocotea) from the Reserva Natural Vale, Linhares, Espírito Santo, Brazil

“…Neotropical genus comprising about 24 species (van der Werff, ; Alves and Souza, ; Moraes et al., ; Moraes, ), distributed from Bolivia, Colombia, Ecuador, Peru, Venezuela, Guyana, French Guiana, Suriname to southeast Brazil, 18 species occurring in Brazil, mostly in Amazonia. In Espírito Santo, there are three species, one recently described from collections made in the Reserva Natural Vale.…”