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Species distribution patterns in sharp environmental gradients: downscaling of a biogeographical framework (Daraina region, NE Madagascar)

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Louis Nusbaumer
added 12 research items
A new aroid species endemic to northern Madagascar, Carlephyton darainense, is described and illustrated. The new species differs from the similar C. madagascariense by the male flowers with laxly arranged synandria, each consisting of two stamens with the filaments basally connate but apically free and turned horizontally, and a long cylindric style in the female flowers, whereas in C. madagascariense the male flowers have densely arranged synandria, each consisting of two to six completely connate stamens, and a short conical style in female flowers. The distribution and ecology of C. darainense are briefly discussed, a comparison with the three other species of the genus and a key to all four species are included. Une nouvelle espèce d'Aracée endémique du nord de Madagascar, Carlephyton darainense est décrite et illustrée. Elle diffère principalement de C. madagascariense par ses fleurs mâles avec des synandries lâches et composées de deux étamines dont les filets sont soudés à la base mais libres à l'apex et tournés horizontalement et par ses fleurs femelles composées d'un long style cylindrique alors que chez C. madagascariense, les synandries sont compactes et composées de deux à six étamines soudées et les fleurs femelles sont composées d'un style conique court. La distribution et l'écologie de la nouvelle espèce sont brièvement analysées. Cette espèce est comparée aux autres espèces du genre et une clé de détermination des espèces est incluse.
Cribb, P., L. Nusbaumer & L. Gautier (2012). Angraecum darainense P. J. Cribb & Nusb. and Aeranthes unciformis P. J. Cribb & Nusb. (Orchidaceae), two new species from northern Madagascar. Candollea 67: 269–275. In English. English and French abstracts. Two new orchid species, Angraecum darainense P. J. Cribb & Nusb. and Aeranthes unciformis P. J. Cribb & Nusb. (Orchidaceae) from northern Madagascar are described here, illustrated and compared with other species in their respective genera. Angraecum darainense appears to be related to Angraecum melanostictum Schltr., but differs in having flowers with a longer spur and leaves more densely arranged on the longer stems, leaf blade much shorter and narrower. Aeranthes unciformis appears to be related to Aeranthes caudata Rolfe, but differs by having flowers borne two or three at a time and having a very distinctive transversely elliptic lip tapering into a long acumen at the tip and a distinctive dorsal sepal curving forwards over the column and lip. The distribution, ecology and conservation status of these two orchids species are briefly discussed.
Cadia multifoliolata Nusb. & Labat (Fabaceae, Papilionoideae), a new species from NE Madagascar, is described, illustrated and compared with the other seven species in the genus. This new species differs from the six other endemic species of Madagascar by the large number of leaflets and the morphology of the flowers. With its high leaflet number, Cadia multifoliolata is close to the North-East African and Arabian species Cadia purpurea (G. Piccioli) Aiton, but presents several differences with its shorter inflorescence bracts and its shorter hypanthium. Cadia multifoliolata is only known from the locality in the Daraina (Loky-Manambato) region in NorthEast Madagascar. This area is localized at the crossroads of four main phytogeographic units of Madagascar and presents a very steep environmental gradients.
Louis Nusbaumer
added 3 research items
Cribb, P., L. Gautier & L. Nusbaumer (2013). How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? Candollea 68: 41–49. In English, English and French abstract. The holomycotrophic genus Didymoplexis Griff. (Orchidaceae) is revisited for Madagascar. Two species, Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut. and Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut. are newly described based on recently collected flowering specimens. The relationship between these two species, the recently observed Didymoplexis verrucosa J. Stewart & Hennessy and the cryptic Didymoplexis madagascariensis (H. Perrier) Summerh., only known from two fruiting specimens, is discussed. A key to species in the genus in Madagascar and Africa based on flowering material is provided.
Wahlert, G. A., L. Nusbaumer & L. Gautier (2013). Rinorea ranirisonii Nusb. & Wahlert (Violaceae): a new species from the Daraina region of northern Madagascar. Candollea 68: 87–92. In English, English and French abstracts. Rinorea ranirisonii Nusb. & Wahlert (Violaceae), a new species from the Daraina region of northern Madagascar, is described and illustrated. This species, with opposite leaves and endemic to Madagascar, is immediately distinguished from all other species belonging to Rinorea subsect. Verticillatae Engl. by its young branches, upper and lower leaf surfaces, inflorescence axis, pedicels, sepals, and ovary covered in golden-reddish hispid indumentum. Distribution and ecology of the new species are discussed and a preliminary IUCN conservation assessment is given.
Castillon, J.-P. & L. Nusbaumer (2014). Aloe gautieri J.-P. Castillon & Nusb. (Xanthorrhoeaceae), a new species from the northeastern coast of Madagascar. Candollea 69: 75–80. In English. English and French abstracts. Aloe gautieri J.-P. Castillon & Nusb. (Xanthorrhoeaceae, Asphodeloideae), a new species from the northeastern coast of Madagascar is described and illustrated. The new species is morphologically closely related to Aloe fragilis Lavranos & Röösli but differs in having paler flowers, more elongated racemes, ungrouped cauline leaves forming no compact rosette. The distribution, ecology and conservation status of the new species are presented along with a line drawing and colour pictures.
Louis Nusbaumer
added 2 research items
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.
Wahlert, G. A., L. Nusbaumer & P. Ranirison (2014). Grewia gautieri Wahlert & Nusb. (Malvaceae, Grewioideae): a new species from Madagascar. Candollea 69: 149–155. In English, English and French abstracts. Grewia gautieri Wahlert & Nusb. (Malvaceae, Grewioideae), a new species from Madagascar, is described and illustrated. This new species is similar to Grewia brideliifolia Baill. by its 4-merous flowers, 3-flowered cymes, and drupaceous fruits, but differs by its chartaceous leaves, petals that usually lack a nectariferous gland, and fruits that contain a single pyrene. The distribution and ecology of the species are presented, and an IUCN conservation status is provided.