Cynthia Hong-Wa

Intricate patterns of phylogenetic relationships in the olive family as inferred from multi-locus plastid and nuclear DNA sequence analyses: A close-up on Chionanthus and Noronhia (Oleaceae)

Noronhia represents the most successful radiation of the olive family (Oleaceae) in Madagascar with more than 40 named endemic species distributed in all ecoregions from sea level to high mountains. Its position within the subtribe Oleinae has, however, been largely unresolved and its evolutionary history has remained unexplored. In this study, we generated a dataset of plastid (trnL-F, trnT-L, trnS-G, trnK-matK) and nuclear (internal transcribed spacer [ITS]) DNA sequences to infer phylogenetic relationships within Oleinae and to examine evolutionary patterns within Noronhia. Our sample included most species of Noronhia and representatives of the ten other extant genera within the subtribe with an emphasis on Chionanthus. Bayesian inferences and maximum likelihood analyses of plastid and nuclear data indicated several instances of paraphyly and polyphyly within Oleinae, with some geographic signal. Both plastid and ITS data showed a polyphyletic Noronhia that included Indian Ocean species of Chionanthus. They also found close relationships between Noronhia and African Chionanthus. However, the plastid data showed little clear differentiation between Noronhia and the African Chionanthus whereas relationships suggested by the nuclear ITS data were more consistent with taxonomy and geography. We used molecular dating to discriminate between hybridization and lineage sorting/gene duplication as alternative explanations for these topological discordances and to infer the biogeographic history of Noronhia. Hybridization between African Chionanthus and Noronhia could not be ruled out. However, Noronhia has long been established in Madagascar after a likely Cenozoic dispersal from Africa, suggesting any hybridization between representatives of African and Malagasy taxa was ancient. In any case, the African and Indian Ocean Chionanthus and Noronhia together formed a strongly supported monophyletic clade distinct and distant from other Chionanthus, which calls for a revised and more conservative taxonomy for this group.

Endemic families of Madagascar. XII. Resurrection and taxonomic revision of the genera Mediusella (Cavaco) Hutchinson and Xerochlamys Baker (Sarcolaenaceae)

Hong-Wa C. 2009. — Endemic families of Madagascar. XII. Resurrection and taxonomic revision of the genera Mediusella (Cavaco) Hutchinson and Xerochlamys Baker (Sarcolaenaceae). Adansonia, sér. 3, 31 (2): 311-339. ABSTRACT The position of Leptolaena subgenera Mediusella Cavaco and Xerochlamys (Baker) Cavaco with respect to Leptolaena Thouars and Sarcolaena Thouars has long been debated along with the circumscription of species within these two groups. Recent advances in the molecular phylogeny of Sarcolaenaceae indicate that both Mediusella and Xerochlamys are not part of Leptolaena, requiring a generic recircumscription of the entities in the Leptolaena-Sarcolaena-Mediusella-Xerochlamys clade. The results of a previous multivariate analysis of morphological characters also showed that Mediusella and Xerochlamys include two and eight entities respectively, which are recognized here as distinct species. Three species of Xerochlamys (X. coriacea, X. itremoensis and X. undulata) are described as new, and Mediusella arenaria requires a new combination. The three new species are distinguished by their habit, the size, pubescence and margin of their leaves, and the structure of their inflorescences. A key to the species and information on their distribution, ecology and phenology are given. The conservation status of each species is evaluated according to IUCN Red List criteria; six species are considered endangered (EN), two are vulnerable (VU), one is near threatened (NT) and the last is of least concern (LC).

Endemic Families of Madagascar. XIII. New, restricted range species of Eremolaena Baill. and Schizolaena Thouars (Sarcolaenaceae)

Abstract Lowry II, P. P., L. Nusbaumer, A. Randrianasolo, G. E. Schatz & C. Hong-Wa (2014). Endemic Families of Madagascar. XIII. New, restricted range species of Eremolaena Baill. and Schizolaena Thouars (Sarcolaenaceae). Candollea 69: 183–193. In English, French and English abstracts. One new species of Eremolaena Baill. and two new species of Schizolaena Thouars (belonging to the family Sarcolaenaceae) are described, illustrated and compared with the members of their respective genera they most closely resemble. Eremolaena darainensis Nusb. & Lowry is similar to Eremolaena rotundifolia (F. Gérard) Danguy but differs from it by features of the indument on the leaves and the sepals, and occurs only in the Loky-Manambato (Daraina) region of far north-eastern Madagascar, where it occurs in semi-deciduous forest on granite. Schizolaena charlotteae Lowry & G. E. Schatz resembles Schizolaena milleri Lowry & al. but is distinguished by differences in sepal indument, petal color, the number of stamens, and the length of the processes borne on the involucre in fruit. Schizolaena parvipetala Randrian. & Hong-Wa is similar to Schizolaena gereaui Lowry & al. but differs by petal size, leaf acumen length, the number of stamens, and the number of flowers per involucre. Both new species of Schizolaena Thouars are only known from lowland humid forest in far south-eastern Madagascar, in the vicinity of the city of Tolagnaro. The distribution and ecology of each species are discussed and preliminary IUCN conservation assessments are provided.

Taxonomy and conservation of the genus Noronhia Thouars (Oleaceae) in Mauritius

Abstract Hong-Wa, C., M. W. Callmander & C. Baider (2014). Taxonomy and conservation of the genus Noronhia Thouars (Oleaceae) in Mauritius. Candollea 69: 157–163. In English, English abstract. The genus Noronhia Thouars (Oleaceae), formerly known only from Madagascar and the Comoros, also occurs in Continental Africa and the Mascarene Islands. We present a taxonomic and conservation overview of the genus in Mauritius. Two new combinations are proposed for the Mauritian endemic species previously recognized in Chionanthus L. and described in Olea L.: Noronhia macrophylla (Baker) Hong-Wa & Callm. & Noronhia obovata (Baker) Hong-Wa & Callm. while the third species occurring on the island, a Mascarene endemic, already has a valid name in Noronhia: Noronhia broomeana Oliv. Applying the IUCN Red List Categories and Criteria, the three species occurring on Mauritius are considered as threatened with extinction. Discussion on the conservation status of each species is provided.