Louis Nusbaumer

Une nouvelle espèce d'orchidée, Angraecum goldschmidii, est décrite de l'aire protégée de Loky Manambato (région de Daraina), dans le nord de Madagascar. Elle est illustrée et comparée aux espèces similaires du genre, en particulier à celles actuellement placées dans la section Pectinaria (Benth.) Schltr. L'historique nomenclatural et, en particulier, le statut de Pectinaria et de Pectinariella Szlach., Mytnik & Grochocka, sont discutés. La nouvelle espèce est considérée comme la plus proche morphologiquement d'Angraecum polyphemus Hermans & Verlynde. La distribution et l'écologie de la nouvelle espèce sont présentées et son statut de conservation préliminaire est évalué suivant les Catégories et Critères de la Liste rouge de l'UICN. Received: 2 June 2026; Accepted: 27 July 2026; First published online: 9 September 2026

Accurate land-cover mapping in tropical regions remains challenging because of high environmental heterogeneity, complex vegetation structure, and persistent cloud cover. Recent geospatial foundation models provide pre-computed Geo-embeddings that offer a new representation of Earth Observation data (EO), yet their potential for detailed tropical land-cover mapping and their performance relative to, and in combination with, conventional Sentinel-1 and Sentinel-2 satellite image time series remains largely unexplored. This study evaluated AlphaEarth Foundation Geo-embeddings for detailed vegetation mapping in northern Madagascar and investigated whether combining them with satellite image time series processed using the Satellite Image Time Series (SITS) R package could improve classification performance. Geo-embeddings were classified using a Random Forest model (GEO), while four supervised classifiers were trained on Sentinel-1 and Sentinel-2 time series. GEO achieved the highest standalone performance (OA = 0.74), outperforming all classifiers trained on the satellite image time series. Probability-level ensemble models were then used to assess whether both data representations could be beneficially combined. The best-performing ensemble, combining GEO (75%) with Temporal Convolutional Neural Network (TempCNN; 25%), increased overall accuracy from 0.74 to 0.82. These results suggest that Geo-embeddings provide an effective standalone representation for detailed tropical land-cover mapping and indicate that combining them with conventional satellite image time series may exploit complementary information. As geospatial foundation models continue to evolve, understanding how they can be integrated with established Earth observation workflows may support future operational land-cover mapping.

Les recherches taxonomiques et moléculaires sur les genres de la sous-tribu Goodyerinae de Madagascar et des îles adjacentes de l'océan Indien occidental sont discutées. Les caractéristiques de Goodyera R.Br. et Platylepis A.Rich. sont comparées, et leur histoire est présentée. Les espèces actuellement acceptées par les auteurs pour la région sont détaillées. Une nouvelle espèce d'orchidée, Platylepis avaratraensis Hermans & Nusb., est décrite dans la région de Sava, au nord de Madagascar. Elle est illustrée et comparée à d'autres espèces du genre. Elle est la plus proche de P. humicola (Schltr.) Schltr., mais se distingue par ses feuilles plus larges, ses bractées florales plus courtes, la couleur de ses fleurs, des sépales plus étroits et un labelle avec des callosités distinctes. La distribution et l'écologie de la nouvelle espèce sont discutées et son statut de conservation préliminaire est évalué comme «En danger» suivant les Catégories et Critères de la Liste rouge de l'UICN.

We investigated here speciation and diversification mechanisms in Turraea and allied genera (Meliaceae-Turraeeae) from Madagascar and continental Africa, as well as their generic delimitations. Our goal was to contribute to an improved understanding of the origin and diversification of the Malagasy and African floras. Using target-enrichment sequencing, we assembled a nuclear dataset comprising 64 taxa (75% of the group’s species diversity) to reconstruct phylogenetic relationships within the group. We estimated divergence times and diversification rate shifts and assessed the prevalence of incomplete lineage sorting and introgression/hybridization. The group appears to have originated in the Eocene, probably in southern Africa, with a diversification rate shift occurring in the Miocene coinciding with the colonization of Madagascar. This shift, associated with incomplete lineage sorting and introgression/hybridization, suggests a rapid diversification linked to the onset of the Indian Monsoon. We propose a revised generic classification, including a new key and synoptic descriptions of the genera, to accommodate the polyphyly of Turraea. In this context, we place the endemic Malagasy genera Humbertioturraea and Calodecaryia in synonymy under Turraea, and resurrect the South African genus Nurmonia and the Angolan and Indian genus Naregamia. We therefore publish the necessary new combinations in Nurmonia and Turraea.

Desmochaeta (now Cyathula) achyranthoides was described from South America and reported to be a widespread tropical plant in both Africa and the Americas. A revision of herbarium material revealed that inter alia leaf shape differs between the populations of the Eastern and Western Hemispheres. Therefore, we maintain the name C. achyranthoides s.str. for the American populations and re-instate the name C. geminata for most of the African plants. Both species are found in tropical evergreen forests, mainly at low altitudes. Furthermore, two mountain species, C. brevispicata from Madagascar and C. aethiopica from east tropical Africa, which were previously identified as C. achyranthoides, are described as new to science. Compared to both C. achyranthoides and C. geminata, these new species have short inflorescences and longer, recurved or uncinate perianths in the fertile flowers and morphologically resemble C. fernando-poensis; the latter is only known from the mountains of Equatorial Guinea (Bioko Island), south-west and (newly recorded here) North-West Regions of Cameroon. The species under study are compared with one another and with the related, pantropically distributed species C. prostrata; their synonymy is verified and typifications are established. The fine-level partial florescence (cyme) structure of each species is also studied, with further taxonomic implications. Cyathula geminata seems to be restricted to west and central tropical Africa, with its range replaced eastwards by C. aethiopica and in Madagascar by C. brevispicata.