Capurodendron is the largest endemic genus of plants from Madagascar, with around 76% of its species threatened by deforestation and illegal logging. However, some species are not well circumscribed and many of them remain undescribed, impeding a confident evaluation of their conservation status. Here we focus on taxa delimitation and conservation of two species complexes within Capurodendron: the Arid and Western complexes, each containing undescribed morphologies as well as intermediate specimens alongside well-delimited taxa. To solve these taxonomic issues, we studied 381 specimens morphologically and selected 85 of them to obtain intergenic, intronic, and exonic protein-coding sequences of 794 nuclear genes and 227 microsatellite loci. These data were used to test species limits and putative hybrid patterns using different approaches such as phylogenies, PCA, structure analyses, heterozygosity level, FST, and ABBA-BABA tests. The potential distributions were furthermore estimated for each inferred species. The results show that the Capurodendron Western Complex contains three well-delimited species, C. oblongifolium, C. perrieri, and C. pervillei, the first two hybridizing sporadically with the last and producing morphologies similar to, but genetically distinct from C. pervillei. The Arid Complex shows a more intricate situation, as it contains three species morphologically well-delimited but genetically intermixed. Capurodendron mikeorum nom. prov. is shown to be an undescribed species with a restricted distribution, while C. androyense and C. mandrarense have wider and mostly sympatric distributions. Each of the latter two species contains two major genetic pools, one showing interspecific admixture in areas where both taxa coexist, and the other being less admixed and comprising allopatric populations having fewer contacts with the other species. Only two specimens out of 172 showed clear genetic and morphological signals of recent hybridization, while all the others were morphologically well-delimited, independent of their degree of genetic admixture. Hybridization between Capurodendron androyense and C. microphyllum, the sister species of the Arid Complex, was additionally detected in areas where both species coexist, producing intermediate morphologies. Among the two complexes, species are well-defined morphologically with the exception of seven specimens (1.8%) displaying intermediate patterns and genetic signals compatible with a F1 hybridization. A provisional conservation assessment for each species is provided.
Timber of the family Sapotaceae are appreciated for their physical properties internationally as well as locally, which often put a serious pressure on species survival. Taxonomic efforts are badly needed before producing reliable conservation assessments for the Malagasy species. In the framework of the revision of three related Sapotaceae genera, all endemic from Madagascar and surrounding islands of the Western Indian Ocean, a new species of Labramia A. DC. has been identified. It is described and illustrated here. Labramia ambondrombeensis L. Gaut. & Randriarisoa is one of the two Labramia species that have relatively small leaves. It is compared to Labramia platanoides Capuron ex Aubrév., the other small-leaved species from which it differs in leaf shape, pedicel size and ovary cell number. Labramia ambondrombeensis is known from a single collection that comes from a littoral forest in the Northeastern coast of the island, lacking any legal protection and is preliminary assessed as "Critically Endangered" using the IUCN Red List Criteria. RésuméRANDRIARISOA, A., Y. NACIRI & L. GAUTIER (2020). Labramia ambondrombeensis (Sapotaceae), une nouvelle espèce en danger critique d' extinction de Madagascar. Candollea 75: 83 -87. En anglais, résumés anglais et français.
Previous phylogenetic studies have demonstrated that the Manilkarinae are a monophyletic subtribe if Northia is excluded. The subtribe consists of four genera: Faucherea, Labourdonnaisia, Labramia and Manilkara. However, the same phylogenetic studies also raised taxonomic issues concerning unclear generic delimitations and unresolved relationships. The current study's aims are: to resolve these taxonomic issues using a molecular phylogeny based on hundreds of nuclear markers sequenced from a representative sampling of taxa across the four genera; to find relevant morphological characters allowing the distinction of the clades retrieved with the phylogeny; and finally to understand the evolutionary history of the subtribe by conducting a divergence time estimation and ancestral state reconstructions. Our phylogeny shows a well‐resolved backbone with four main lineages: the Labramia clade, the main clade of Manilkara, a clade in which all species of Labourdonnaisia and Faucherea are mixed, and a clade of three Pacific Manilkara species. The main clade of Manilkara is retrieved as sister to Labramia, and the Labourdonnaisia‐Faucherea clade is clearly assessed as sister to the three Pacific Manilkara species. As a consequence, Faucherea is synonymized with Labourdonnaisia, and the three Pacific Manilkara are considered to be a separate genus, for which the name Abebaia is resurrected. We provide emended descriptions for Labourdonnaisia and Abebaia as well as the necessary new combinations. The ancestral state reconstruction of flower characters shows that ancestral Manilkarinae were characterized by a hexamerous corolla, well‐developed dorsal appendages and staminodes, and a pubescent ovary. These character states have been retained in the main Manilkara clade, but surprisingly also in Abebaia, which appears as a cryptic genus. The lack of dorsal appendages and the reduction of staminodes observed in Labourdonnaisia appeared after the split from Abebaia. The increase in corolla merism observed mainly in the Mascarene Labourdonnaisia, which was used to separate it from Faucherea, appears to be a derived state, which evolved separately in a few species during the radiation of Labourdonnaisia on Madagascar and the Mascarenes. The glabrous ovary state observed in Labramia also constitutes a derived synapomorphic state in the genus.
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