A revision of the indusiate scaly tree ferns (Cyatheaceae, Cyathea subgen. Alsophila sect. Alsophila) in Madagascar, the Comoros and the Seychelles Thomas JANSSEN Muséum national d’Histoire naturelle, Département Systématique et Évolution, UMR-CNRS 5202 / USM 0602, case postale 39, 57 rue Cuvier, F-75231 Paris cedex 05 (France) and Albrecht von Haller Institute of Plant Sciences, Department of Systematic Botany, Georg August University Göttingen, Untere Karspüle 2, D-37073 Göttingen (Germany) current address: Research Institute Senckenberg, Department of Botany, Senckenberganlage 25, D-60325 Frankfurt (Germany) [email protected] France RAKOTONDRAINIBE École Pratique des Hautes Études and Muséum national d’Histoire naturelle, Département Systématique et Évolution, UMR-CNRS 5202 / USM 0602, case postale 39, 57 rue Cuvier, F-75231 Paris cedex 05 (France) [email protected] Janssen T. & Rakotondrainibe F. 2008. — A revision of the indusiate scaly tree ferns (Cyathe- aceae, Cyathea subgen. Alsophila sect. Alsophila) in Madagascar, the Comoros and the Seychelles. Adansonia, sér. 3, 30 (2) : 221-376. ABSTRACT Based on the examination of herbarium specimens including numerous recent collections and on observations of most species in situ, we herein present a revi- sion of the indusiate scaly tree ferns (Cyathea sect. Alsophila) for Madagascar, the Comoros and the Seychelles. One endemic species occurs on the Seychelles and three taxa (one endemic) are found on the Comoros. For Madagascar, we describe 55 taxa (40 species and 15 varieties), 51 of which are endemic. Among these, 11 species and 12 varieties are new. Th e species newly described for Madagascar com- prise C. basirotundata Rakotondr. & Janssen, C. conferta Janssen & Rakotondr., C. dilatata Rakotondr. & Janssen, C. emilei Janssen & Rakotondr., C. hebes Janssen & Rakotondr., C. lisiae Janssen & Rakotondr., C. longispina Janssen & Rakotondr., C. meridionalis Janssen & Rakotondr., C. obtecta Rakotondr. & Janssen, C. pseudo- bellisquamata Janssen & Rakotondr., and C. valdesquamata Janssen & Rakotondr. Th e newly described varieties are C. acutula (R.M.Tryon) Janssen & Rakotondr. var. deltoidea Janssen & Rakotondr., C. a. var. rufescens Janssen & Rakotondr., C. bellisquamata Bonap. var. ambrensis Janssen & Rakotondr., C. b. var. australis ADANSONIA, sér. 3 • 2008 • 30 (2) © Publications Scientifi ques du Muséum national d’Histoire naturelle, Paris. www.adansonia.com 221 Janssen T. & Rakotondrainibe F. Janssen & Rakotondr., C. boivinii Mett. ex Kuhn var. andringitrensis Janssen & Rakotondr., C. b. var. bevolo Janssen & Rakotondr., C. b. var. parahildebrandtii Janssen & Rakotondr., C. decrescens Mett. ex Kuhn var. cristata Janssen & Rako- tondr., C. d. var. manongarivensis Janssen & Rakotondr., C. emilei var. dauphinensis Janssen & Rakotondr., C. similis C.Chr. var. leptoderma Rakotondr. & Janssen, and C. s. var. montana Janssen & Rakotondr. Th e descriptions of previously rec- ognized taxa have been completed and where necessary corrected. Especially such KEY WORDS characters have been added, that can be observed only in situ, e.g. trunk morphol- Cyatheaceae, Alsophila, ogy and measurements of the entire leaf. Descriptions are accompanied by plates Cyathea, with detailed illustrations and by distribution maps. We thoroughly reviewed the Comoros, Madagascar, nomenclatural status and typifi cation of all names. We provide determination keys Seychelles, down to the varietal level including all taxa of Cyatheaceae of the Madagascan diversity centre, region. Photographic documentation of the trunk and habit of most species will new species, new variety, facilitate determination in the fi eld. Finally, we briefl y comment on the distribu- typifi cation. tion of the tree fern diversity in the Madagascan rainforests. RÉSUMÉ Révision des fougères arborescentes indusiées à écailles (Cyatheaceae, Cyathea subgen. Alsophila sect. Alsophila) à Madagascar, aux Comores et aux Seychelles. Nous présentons ici une révision des fougères arborescentes indusiées à écailles (Cyathea sect. Alsophila) pour Madagascar, les Comores et les Seychelles basée sur l’étude de spécimens d’herbier provenant en grande partie de récoltes récentes et sur l’observation de la majorité des espèces in situ. Une espèce endémique croît aux Seychelles ; trois taxons, dont un endémique, ont été recensés aux Comores ; pour Madagascar, nous décrivons 55 taxons (40 espèces et 15 variétés) dont 51 sont endémiques. Parmi eux, 11 espèces et 12 variétés sont nouvelles. Les espèces nouvellement décrites à Madagascar sont Cyathea basirotundata Rakotondr. & Janssen, C. conferta Janssen & Rakotondr., C. dilatata Rakotondr. & Janssen, C. emilei Janssen & Rakotondr., C. hebes Janssen & Rakotondr., C. lisiae Jans- sen & Rakotondr., C. longispina Janssen & Rakotondr., C. meridionalis Janssen & Rakotondr., C. obtecta Rakotondr. & Janssen, C. pseudobellisquamata Janssen & Rakotondr. et C. valdesquamata Janssen & Rakotondr. Les variétés nouvelles sont C. acutula (R.M.Tryon) Janssen & Rakotondr. var. deltoidea Janssen & Rakotondr., C. a. var. rufescens Janssen & Rakotondr., C. bellisquamata Bonap. var. ambrensis Janssen & Rakotondr., C. b. var. australis Janssen & Rakotondr., C. boivinii Mett. ex Kuhn var. andringitrensis Janssen & Rakotondr., C. b. var. bevolo Janssen & Rakotondr., C. b. var. parahildebrandtii Janssen & Rako- tondr., C. decrescens Mett. ex Kuhn var. cristata Janssen & Rakotondr., C. d. var. manongarivensis Janssen & Rakotondr., C. emilei var. dauphinensis Janssen & Rakotondr., C. similis C.Chr. var. leptoderma Rakotondr. & Janssen et C. s. var. montana Janssen & Rakotondr. Les descriptions des taxons déjà connus ont été élargies et corrigées si nécessaire. Elles ont été notamment complétées avec les caractères observables uniquement in situ tels l’aspect du tronc et les dimensions MOTS CLÉS de la feuille entière. Les descriptions sont accompagnées de planches de dessins Cyatheaceae, Alsophila, détaillées et de cartes de répartition. Le statut nomenclatural et la typifi cation Cyathea, de tous les noms ont été rigoureusement revus. Nous mettons à disposition Comores, Madagascar, des clés de détermination incluant tous les taxons des Cyatheaceae de la région Seychelles, malgache jusqu’au niveau variétal. La documentation photographique du tronc centre de diversité, et du port de la majorité des espèces facilitera la détermination sur le terrain. espèce nouvelle, variété nouvelle, Enfi n, nous commentons brièvement la distribution de la diversité des fougères typifi cation. arborescentes dans les forêts denses humides de Madagascar. 222 ADANSONIA, sér. 3 • 2008 • 30 (2) Revision of Cyathea subgen. Alsophila sect. Alsophila INTRODUCTION tondrainibe (2006). Cyatheaceae are not known to occur on other islands in the Western Indian Classifi cation within the scaly tree ferns (Cya- Ocean except those mentioned above. theaceae) has been and currently still is an object Th e tree ferns of the Comoros are treated to- of controversy (Tryon 1977; Holttum 1977, 1981; gether with the Madagascan fl ora because three Holttum & Edwards 1983). In agreement with the out of four taxa found on the Comoros also occur most recent accounts for Africa and Madagascar on Madagascar. Th e Seychelles are included in this (Christensen 1932; Tardieu-Blot 1951; Schelpe & account because of close morphological affi nities Anthony 1986; Burrows 1990; Edwards 2005), of the single endemic species to Madagascan taxa. we recognize a single genus, Cyathea Sm., for the Th e tree ferns of the Seychelles have been treated by purpose of this study. If future authors decide to Baker (1877), Christensen (1912) and Tardieu-Blot assign the rank of genus to the evolutionary lineages (1960). Detailed accounts on the Madagascan tree within the scaly tree ferns reported by Korall et al. ferns have been published by Christensen (1932) and (2007), several new combinations may need to be Tardieu-Blot (1951), the latter also including the proposed. We paid attention on choosing epithets Comoran species. As has been previously discussed for newly described taxa currently unique in the (Janssen 2006; Janssen & Rakotondrainibe 2006), entire Cyatheaceae to minimize the necessity for a great majority of the available tree fern herbarium the creation of new names in such cases. specimens lack characters necessary for a complete Th e Cyatheaceae are a characteristic component description of the species. With many new specimens of the dense evergreen rainforests in the Madagas- having become available during recent years and can region (Takhtajan 1986), i.e. Madagascar, the taking into account extensive observations made on Mascarenes, the Comoros and the Seychelles. We most species in situ during recent fi eldwork, many of herein present a taxonomic revision of Cyathea Sm. the published descriptions could be complemented sect. Alsophila for Madagascar, the Comoros and and were corrected where necessary. In addition to the Seychelles. Cyathea sect. Alsophila (Holttum the description of 11 new species and 12 new varie- 1981; Holttum & Edwards 1983) has indusiate ties, we therefore include complete descriptions of all sori and pinnate-pinnatifi d to tripinnate leaves. previously published and currently accepted taxa in Aphlebia are only occasionally developed and then the present treatment. For the fi rst time, we provide comparatively small. In the Madagascan region full keys including the varietal level and covering the the section is most diverse on Madagascar where entire tree fern diversity