Identification of priority areas for plant conservation in Madagascar using Red List criteria: rare and threatened Pandanaceae indicate sites in need of protection

A major problem in establishing effective protocols for conserving Madagascar's biodiversity is the lack of reliable information for the identification of priority sites in need of protection. Analyses of field data and information from herbarium collections for members of the plant family Pandanaceae (85 spp. of Pandanus; 6 spp. of Martellidendron) showed how risk of extinction assessments can inform conservation planning. Application of IUCN Red List categories and criteria showed that 91% of the species are threatened. Mapping occurrence revealed centres of richness and rarity as well as gaps in Madagascar's existing protected area network. Protection of 10 additional sites would be required to encompass the 19 species currently lacking representation in the reserve network, within which east coast littoral forests are particularly under represented and important. The effect of scale on assessments of risk of extinction was explored by applying different grid cell sizes to estimate area of occupancy. Using a grid cell size within the range suggested by IUCN overestimates threatened status if based solely upon specimen data. For poorly inventoried countries such as Madagascar measures of range size based on such data should be complemented with field observations to determine population size, sensitivity to disturbance, and specific threats to habitat and therefore potential population decline. The analysis of such data can make an important contribution to the conservation planning process by identifying threatened species and revealing the highest priority sites for their conservatio

Nouvelles données sur le genre <i>Pandanus</i> sect. <i>Imerinenses</i> et sect. <i>Rykiella</i> (Pandanaceae) de Madagascar.

Pandanus imerinensis de la côte est de Madagascar était, jusqu\u27à récemment, placé dans la section Rykiella mais trop de caractères isolent cette espèce des autres espèces de la section (stigmates spiniformes non-caduques, architecture et micromorphologie foliaire). Cette espèce a été placée comme type de la section monospécifique Imerinenses alors que P. macrophyllus, une autre espèce remarquable de la côte est, forme seule la section monospécifique Rykiella. Leurs positions taxonomiques restent peu claires. La découverte récente d\u27un individu mâle de P. imerinensis et d\u27une infrutescence mature de P. macrophyllus permet de mieux comprendre ces espèces isolées morphologiquement. La fleur mâle ainsi que la morphologie du pollen de P. imerinensis, et l\u27infrutescence mature de P. macrophyllus sont décrites pour la première fois. Les relations taxonomiques au sein du genre sont discutées ainsi que leur rôle important dans la biogéographie de l\u27Océan Indien. Une clé des espèces à stigmates spinescents des Pandanus de Madagascar est présentée.Pandanus imerinensis from the east coast of Madagascar was, until recently, assigned to sect. Rykiella but many characters distinguish this species from other taxa found in the section (non-deciduous spiniform stigmas, habit and micromorphology). This species has been placed in the monospecific section Imerinenses. Pandanus macrophyllus, another outstanding species from the east coast is therefore the only species found in section Rykiella. Their taxonomic positions remain unclear. Recently, a staminate plant of P. imerinensis and a mature pistillate plant of P. macrophyllus has been found. These discoveries greatly extend our knowledge of these outstanding species. The staminate flower and pollen morphology of P. imerinensis, the mature pistillate plant of P. macrophyllus are here described for the first time. The taxonomic relationships within the genus are discussed as well as their important role in Indian Ocean biogeography. A key to the spiniform stigmas species of Pandanus in Madagascar is presented

Une nouvelle section du genre <i>Pandanus</i> (Pandanaceae) à Madagascar : <i>Pandanus</i> sect. <i>Tridentistigma</i>

Une récente expédition dans le massif peu connu du Tsaratanana au nord-ouest de Madagascar a permis de décrire une nouvelle section (sect. Tridentistigma), taxonomiquement et biogéographiquement isolée au sein des Pandanus malgaches. Le stigmate, terminé par trois dents, est un caractère connu seulement du sous-genre indomalaysien Rykia. Avec les espèces montagnardes de la sect. Acanthostyla, c\u27est la deuxième section dont des membres se trouvent en haute altitude, dans les massifs du nord de Madagascar. Sa position systématique et biogéographique est discutée.A recent expedition in the north-west Massif of Tsaratanana in Madagascar has allowed us to describe a new section (sect. Tridentistigma), taxonomically and biogeographically isolated in the Madagascan Pandanus. Its stigma is terminated by three teeth, a feature currently known only in the subgenus Rykia from Indomalaysia. This section is the second one growing at high altitude in the northern massif of Madagascar. Its systematic and biogeographic position is discussed.</p