Enlarging the monotypic Monocarpieae (Annonaceae, Malmeoideae): recognition of a second genus from Vietnam informed by morphology and molecular phylogenetics

Abstract

Recent botanical expeditions in central Vietnam yielded an unknown species of Annonaceae that could not be confidently identified to subfamily, tribe, and genus. Preliminary BLAST® searches based on plastid data have suggested that this taxon is genetically closely-related to the following tribes of subfamily Malmeoideae: Malmeeae, Fenerivieae, Maasieae, Phoenicantheae, Dendrokingstonieae, Monocarpieae, and Miliuseae. Using representatives of Piptostigmateae, another tribe of Malmeoideae, as outgroups and including representatives of all other tribes of Malmeoideae, molecular phylogenetic analyses of seven combined plastid markers (rbcL, matK, ndhF, ycf1 exons; trnL intron; trnL-trnF, psbA-trnH intergenic spacers) inferred the enigmatic Vietnamese taxon as belonging to the monotypic tribe Monocarpieae. Detailed morphological comparisons between this taxon and its sister group, Monocarpia Miq., warranted the recognition of a second genus of Monocarpieae to accommodate our unknown taxon: Leoheo Chaowasku with a single species, Leoheo domatiophorus Chaowasku, D.T. Ngo & H.T. Le. The morphology of the new genus agrees well with the diagnostic traits of Monocarpieae, e.g., a percurrent tertiary venation of the leaves, a highly reduced number of carpels per flower, enlarged and lobed stigmas, multiple ovules/seeds per ovary/monocarp, considerably large monocarps with a hardened pericarp when dry, and spiniform ruminations of the endosperm. However, the new genus does not exhibit two characteristic features of Monocarpia: terminal inflorescences and generally distinct intramarginal leaf veins. In addition, the new genus possesses three autapomorphic characters: hairy domatia on the lower leaf surface, longitudinal ridges on the monocarp surface, and subsessile monocarps with a stout stipe. The tribe Monocarpieae is consequently enlarged to include the genus Leoheo. The enlarged Monocarpieae, along with the recently established monotypic tribe Phoenicantheae and two other related tribes, Dendrokingstonieae and Miliuseae, are discussed.

Phylogenomics of the Major Tropical Plant Family Annonaceae Using Targeted Enrichment of Nuclear Genes

“…Annonaceae is a pantropical family of trees, shrubs and lianas and is among the most species-rich lineages of tropical rain forest plants (Chatrou et al, 2012a). To date Annonaceae contain 110 genera and around 2,430 species (Chatrou et al, 2012b; Guo et al, 2017b; Chaowasku et al, 2018; Xue et al, 2018). Phylogenetic analyses of the family started in the 1990's with a morphology-based phylogenetic tree published by Doyle and Le Thomas (1994) providing a first cladistic understanding of relationships within the family.…”

Artabotrys angustipetalus (Annonaceae), a new species from Thailand, including a plastid phylogeny and character evolutionary analyses of thorn occurrence in Artabotrys

“…DNA extraction, amplification and sequencing, including primer sequences, used in the present study followed Chaowasku & al. (2018aChaowasku & al.…”

Toward a phylogenetic reclassification of the subfamily Ambavioideae (Annonaceae): establishment of a new subfamily and a new tribe

“…All methods for DNA extraction, amplification, and sequencing used in the present study were the same as those described in Chaowasku et al (2018a;. For plastid regions not included in Chaowasku et al (2018a;, their primer sequences for the amplification and sequencing were obtained from Hoot et al (1995) and Scharaschkin & Doyle (2005) for atpB-rbcL intergenic spacer, with internal primers newly designed for the present study: ATPB-RBCL-INT-A (5'-GGATGCTGAAATAAAGAACAACAGCC -3') and ATPB-RBCL-INT-B (5'-GGCTGTTGTTCTTTATTTCAGCATCC -3'); and Hamilton (1999) for trnS-trnG intergenic spacer, with internal primers newly designed for the present study: TRNSG-NEW-F-SHORT (5'-CCTCTTTGATTCCGTACGAAAGG -3'), TRNSG-NEW-R (5'-GTCGAATAAGCGAATGAGACG -3'), and TRNSG-INT-R-SHORT (5'-GGAATGGAAATAGCCTTTGTCAC -3').…”

“…Annonaceae, a pantropical family of flowering plants prominent in lowland rainforests, consist of 110 genera (Guo et al 2017;Chaowasku et al 2018a;Xue et al 2018) and approximately 2430 species (Chatrou et al 2018). The family has been classified into four subfamilies, viz., Anaxagoreoideae, Ambavioideae, Annonoideae, and Malmeoideae; the last two subfamilies, which constitute the majority of generic and species diversity in the family, have each been further subdivided into tribes (Chatrou et al 2012).…”