Abstract
The generic status of Winitia Chaowasku (Annonaceae Juss., Miliuseae Hook.f. & Thomson) is reaffirmed by an extensive phylogenetic reconstruction using seven plastome regions (matK, ndhF, rbcL, ycf1 exons; trnL intron; psbA-trnH, trnL-trnF intergenic spacers) and including, among others, seven accessions of Winitia plus two accessions of its sister group, Stelechocarpus Hook.f. & Thomson. The results disclosed a maximally supported clade of Winitia, as well as of Stelechocarpus. The sister relationship of the two genera is still rather poorly supported and the branch uniting them is very short, whereas the branches leading to Winitia and to Stelechocarpus are relatively long, corresponding to their considerable morphological differences. Additionally, in Miliuseae there is a particular indel of eight continuous base pairs in the trnL-trnF intergenic spacer potentially diagnostic for generic discrimination, i.e., members in the same genus possess the same indel structure (absence or presence of a gap), and this indel differentiates Winitia from Stelechocarpus. Winitia cauliflora (Scheff.) Chaowasku appears polyphyletic and Winitia longipes (Craib) Chaowasku & Aongyong comb. nov. based on Stelechocarpus longipes Craib is consequently proposed. Furthermore, our phylogenetic data support a new species, Winitia thailandana Chaowasku & Aongyong sp. nov. from southern Thailand, which is described and illustrated. A key to genera in the sageraeoid clade (Sageraea-Winitia-Stelechocarpus) and a key to the four species of Winitia are provided.
Highlights
Annonaceae Juss. are a large pantropical family of flowering plants prominent in lowland rainforests and consisting of ca 2430 species (Couvreur et al 2019) in 110 genera (Guo et al 2017b; Chaowasku et al 2018a, 2018b; Xue et al 2018)
The genus is distributed from southern Thailand and southern Vietnam through the Malay Peninsula to Sumatra and Borneo, and currently contains two species: the widespread W. cauliflora (Scheff.) Chaowasku (Chaowasku et al 2013; basionym: Scheffer 1881) and the type species W. expansa Chaowasku (Chaowasku et al 2013) endemic to Thailand; so far, only a single accession of each species has been included in phylogenetic analyses (Chaowasku et al 2013: accession of W. cauliflora was from cultivation in Bogor Botanical Garden, Indonesia)
The genus, was subsumed under Stelechocarpus by Turner (2016), principally based on the arguments that (1) the erection of Winitia has caused Stelechocarpus to become a monotypic genus, which conveys little taxonomic information, and (2) Stelechocarpus inclusive of Winitia is identifiable by a raised leaf midrib adaxially
Summary
Annonaceae Juss. are a large pantropical family of flowering plants prominent in lowland rainforests and consisting of ca 2430 species (Couvreur et al 2019) in 110 genera (Guo et al 2017b; Chaowasku et al 2018a, 2018b; Xue et al 2018). In combination with thorough morphological examinations, a number of previously undescribed genera have been established in the past 12 years (Mols et al 2008; Couvreur et al 2009, 2015; Chaowasku et al 2012, 2013, 2015, 2018a, 2018b; Guo et al 2014; Xue et al 2018) One of these is the genus Winitia Chaowasku (Chaowasku et al 2013), which is closely allied to the monotypic genus Stelechocarpus Hook.f. The genus is distributed from southern Thailand and southern Vietnam through the Malay Peninsula to Sumatra and Borneo, and currently contains two species: the widespread W. cauliflora (Scheff.) Chaowasku (Chaowasku et al 2013; basionym: Scheffer 1881) and the type species W. expansa Chaowasku (Chaowasku et al 2013) endemic to Thailand; so far, only a single accession of each species has been included in phylogenetic analyses (Chaowasku et al 2013: accession of W. cauliflora was from cultivation in Bogor Botanical Garden, Indonesia)
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