Callmander, M.W., R.E. Gereau, B. Offroy, C.M. Taylor, L.G. Lohmann, M.T. Strong, L. Biral & J. Calvo (2024). History of plants sent by Jean-Baptiste Leblond to the Société d'histoire naturelle de Paris and typification of names published by Louis Claude Richard in 1792. Candollea 79: 3–52. In English, English abstract. DOI: http://dx.doi.org/10.15553/c2024v791a2

After Jean-Baptiste-Christian Fusée Aublet, the botanist who spent two years in French Guiana (1762–1764) under the auspices of Louis XV, other botanists and naturalists were sent to the region to look for useful plants, among them, Louis Claude Richard and Jean-Baptiste Leblond. The latter sent natural history collections gathered mostly from French Guiana, together with some from the Antilles, to the Société d'histoire naturelle de Paris [SHNP]. These collections were described in 1792 in the Actes de la Société d'histoire naturelle de Paris and the plant material was treated by Richard. At the breakup of the SHNP, Étienne Pierre-Ventenat bought Leblond's original collections, which were deposited in G by the descendants of Benjamin Delessert. Richard's herbarium was subsequently acquired by Emmanuel Drake del Castillo and ultimately bequeathed to P. Most of the names published in the Actes by Richard were listed in his Catalogus Plantarum manuscript dated 1790 and indicated on his own collections now at P. Therefore, original material of the names published in 1792 can be sought in both the first set of Leblond, now at G, and Richard's herbarium at P. Due to in-depth search of original material in G, P, P-LA, and P-JU, we can here provide a comprehensive list of the 143 names (including 5 new genera) validated by Richard in 1792 as well as information on typification and currently accepted names. Among those names, four remain doubtful because no original material has been traced, and 76 names are still in use today either as originally published or as basionyms of later combinations. Lectotypes are designated for 82 names, including 15 for which a second step lectotypification is necessary, plus one neotype. Two new combinations and a replacement name are further published: Fridericia pilulifera (Rich.) L.G. Lohmann & Callm. (Bignoniaceae), Monteverdia ramiflora (Rich.) Biral & Callm. (Celastraceae), and Ouratea richardii Callm. & J. Calvo (Ochnaceae).

Klackenberg J. & S.G. Razafimandimbison (2024). New rare and threatened species of Peponidium and Pyrostria (Rubiaceae, Vanguerieae) from the drylands of Madagascar. Candollea 79: 53–62. In English, English and French abstracts. DOI: http://dx.doi.org/10.15553/c2024v791a3

Four new species of the tribe Vanguerieae (Rubiaceae) from southern, southwestern and western Madagascar are described and illustrated. Two species belong to the genus Pyrostria Comm. ex Juss.: P. costata Klack. & Razafim. with small leaves and distinctly ribbed pollen presenters and fruits, and P. macrocarpa Klack. & Razafim. characterized by its large, obconical, 5–6-lobed fruits. The other two species belong to the Malagasy subendemic genus Peponidium Arènes: P. leroyi Klack. & Razafim., characterized by hairy leaves with ciliate margins, sparsely pubescent flowers and ribbed pollen presenters, and P. sessile Klack. & Razafim., distinct by its cordate almost sessile leaves and double-tipped corolla lobes. Risk of extinction assessments for all four species are presented, as well as the respective distribution maps.

Klackenberg J. & S.G. Razafimandimbison (2024). Nouvelles espèces rares et menacées dans les genres Peponidium et Pyrostria (Rubiaceae, Vanguerieae) des zones arides de Madagascar. Candollea 79: 53–62. En anglais, résumés anglais et français. DOI: http://dx.doi.org/10.15553/c2024v791a3

Quatre nouvelles espèces de la tribu des Vanguerieae (Rubiaceae) du sud, du sud-ouest et de l'ouest de Madagascar sont décrites et illustrées. Deux espèces appartiennent au genre Pyrostria Comm. ex Juss., à savoir P. costata Klack. & Razafim. avec de petites feuilles et des présentateurs de pollen ainsi que des fruits nettement côtelés, et P. macrocarpa Klack. & Razafim., caractérisée par ses gros fruits obconiques à 5–6 lobes. Les deux autres espèces du genre sous-endémique malgache Peponidium Arènes: P. leroyi Klack. & Razafim., caractérisée par des feuilles poilues à bords ciliés, des fleurs peu pubescentes et des présentateurs de pollen côtelés, et P. sessile Klack. & Razafim., se distinguant par ses feuilles cordées presque sessiles et ses lobes de corolle à double pointe. Les évaluations du risque d'extinction des quatre espèces sont présentées, ainsi que les cartes de répartition respectives.

Chatelain, C., A. Garcin, A. Dobignard, M. Chambouleyron, J.-F. Léger, D. Hoffman & F. Médail (2024). Bioregionalization of the Atlantic Sahara (North Africa): a contribution to the phytogeography of a poorly known area of the largest desert of the world. Candollea 79: 63–96. In English, English abstract. DOI: http://dx.doi.org/10.15553/c2024v791a4

The flora and biogeography of the Atlantic Sahara have been little studied, and most of the corresponding literature was published between 1935 and 1950. The paucity of data on the region reflects, in part, the extreme climate in much of the Atlantic Sahara, but also logistical and geopolitical obstacles. Many biogeographical questions remain unresolved. This paper presents an analysis of 22,000 vascular plant records for southern Morocco, northern Mauritania, and western Algeria. The floristic richness of the Atlantic Sahara (s.str.) is estimated at 578 taxa and subspecies, 78 being endemic (s.l.), yielding an endemism rate of 13 %. Biogeographic and bioclimatic analyses suggest that this area, positioned between the Mediterranean and Afro-tropical regions, forms an important gradient; the Atlantic Sahara may thus be best characterized as an ecotone or transition zone, as it was proposed by White in 1986 for the Sahara as a whole. Based on our geostatistical analyses of climate data and plant occurrences, and supported by recent collections and field observations, we propose a new phytogeographical bioregionalization for the Atlantic Sahara, including four new subregions, conforming to the framework of “Ecoregions of the World”.