Endemic Families of Madagascar. VII. a Synoptic Revision of Leptolaena Thouars Sensu Stricto (Sarcolaenaceae)
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Endemic families of Madagascar. VII. A synoptic revision of Leptolaena Thouars sensu stricto (Sarcolaenaceae) George E. SCHATZ Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166-0299, U.S.A. [email protected] Porter P. LOWRY II Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166-0299, U.S.A. [email protected] Laboratoire de Phanérogamie, Muséum national d’Histoire naturelle, 16 rue Buffon, 75005 Paris, France. [email protected] Anne-Elizabeth WOLF Laboratoire de Phanérogamie, Muséum national d’Histoire naturelle, 16 rue Buffon, 75005 Paris, France. [email protected] ABSTRACT As part of an assessment of the vascular plant families endemic to Madagascar and the Comoro Islands, a synoptic revision is presented of Leptolaena Thouars sensu stricto (Sarcolaenaceae). Unresolved questions of generic deli- mitation among Leptolaena s.s., Mediusella (Cavaco) Hutch., Xerochlamys Baker, and Sarcolaena Thouars preclude a comprehensive revision of Leptolaena sensu lato at the present time. Two previously recognized species are retained (L. multiflora and L. pauciflora), L. cuspidata is resurrected from KEY WORDS synonymy, and five new species are described: L. abrahamii, L. delphinensis, Sarcolaenaceae, L. gautieri, L. masoalensis, and L. raymondii. Preliminary assessments of the Leptolaena, Madagascar, conservation status of each species are provided, along with a key to the conservation. species in English and French. RÉSUMÉ Familles endémiques de Madagascar. VII. Une révision synoptique du genre Leptolaena Thouars sensu stricto (Sarcolaenaceae). Dans le cadre de l’évaluation des familles de plantes vasculaires de Madagascar et des Comores, la révision synoptique du genre Leptolaena Thouars sensu stricto (Sarcolaenaceae) est présentée. Des questions non résolues concernant ADANSONIA, sér. 3 • 2001 • 23 (2) : 171-189 © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. 171 Schatz G.E., Lowry II P.P. & Wolf A.-E. la délimitation générique de Leptolaena s.str., Mediusella (Cavaco) Hutch., Xerochlamys Baker, et Sarcolaena Thouars excluent actuellement la réalisation d’une révision complète de Leptolaena sensu lato. Deux espèces déjà recon- nues (L. multiflora et L. pauciflora) sont retenues ; Leptolaena cuspidata est MOTS CLÉS réhabilité, et cinq nouvelles espèces sont décrites : L. abrahamii, L. delphinensis, Sarcolaenaceae, L. gautieri, L. masoalensis, et L. raymondii. Une évaluation préliminaire pour Leptolaena, Madagascar, la conservation du statut de chaque espèce est présentée, ainsi qu’une clé à conservation. l’espèce, en anglais et en français. INTRODUCTION of the pericarp at maturity into hairs, and Leptolaena sensu stricto possesses hairs at the base This is the seventh in our series of synoptic and sometimes on the interior walls of the revisions of genera in Madagascar’s endemic plant locules. Stipule morphology would appear to ally families (cf. LOWRY et al. 1999, 2000; SCHATZ et Sarcolaena and Xerochlamys, both of which pos- al. 1998, 1999a,b, 2000b), which we are publish- sess stipules fused into a single hood-like struc- ing to provide an updated taxonomic framework ture, versus the free stipules of both Leptolaena for assessing the c. 100 species concerned using s.s. and Mediusella (CAPURON 1970). Stamen the IUCN Red List threat categories (SCHATZ et number has also been used to distinguish genera, al. 2000a), with the ultimate goal of compiling a with Sarcolaena, Xerochlamys, and Mediusella all Red Data Book detailing the conservation status possessing “numerous” stamens, i.e., greater than of each species. For the present paper, our origi- 20, versus Leptolaena s.s. with purportedly 10 sta- nal intention was to review species circumscrip- mens. Closer examination of stamen number in tions within Leptolaena Thouars sensu lato, i.e., Leptolaena s.s. for the new taxa described here including both Mediusella (Cavaco) Hutch. and reveals variable, possibly species-specific values Xerochlamys Baker, thus adopting the broader ranging from 6-8 in L. masoalensis, 8-10 in generic concept of CAVACO (1952a,b). However, L. abrahamii, 10 in L. delphinensis, 10-12 in reconsideration of the characters that have been L. gautieri, and nearly consistently 11 in L. ray- utilized to distinguish the three genera from one mondii. Recent reexamination of pollen of another, as well as to distinguish closely related Sarcolaenaceae showed that differences among Sarcolaena Thouars, has caused us to question the the four genera were insufficient to support either generic limits among the representative taxa. the division into subgenera or recognition at the Sarcolaena has traditionally been circumscribed rank of genus (NILSSON & RANDRIANASOLO to include those taxa that exhibit prefoliation ver- 1999). nation traces on their leaves, a result of an indu- In light of the problems involved in assigning plicate-folded condition of the immature leaves taxa within Leptolaena sensu lato and Sarcolaena during the bud stage, versus the inrolled condi- to genera, we have decided to restrict the present tion in related genera. However, a recently study to Leptolaena sensu stricto, i.e., Leptolaena described species of Sarcolaena entirely lacks ver- subgenus Leptolaena [treated as subgenus nation traces (S. isaloensis Randrianasolo & “Euleptolaena” by CAVACO (1951)], which com- J.S. Mill.), and they are also occasionally absent prises a morphologically coherent group that in in S. eriophora Thouars (RANDRIANASOLO & all likelihood is monophyletic. Leptolaena s.s. can MILLER 1999). CAVACO (1952a,b) emphasized be distinguished by its smaller number of sta- the complete dissociation of the pericarp at matu- mens, generally smaller flowers, and often rity into silky “malpighian” hairs to distinguish glabrous condition. We have examined the speci- Sarcolaena from Leptolaena sensu lato. However, mens at the major herbaria with important hold- Xerochlamys also exhibits comparable dissociation ings of Malagasy plants (K, MO, P, TAN and 172 ADANSONIA, sér. 3 • 2001 • 23 (2) Revision of Leptolaena (Sarcolaenaceae) TEF), and have reviewed the circumscription of Comparative analysis of the available material the species in the group as recognized by CAVACO of Leptolaena sensu stricto has thus enabled us to (1952a,b). propose the following revised taxonomy, in which In the treatment of Chlaenaceae (= Sarco- eight species are recognized, five of which are laenaceae) for the Flore de Madagascar, CAVACO described as new. For the “Material examined” (1952b; see also CAVACO 1952a) recognized seven cited below under each species, abbreviations are species of Leptolaena, two of which (L. multiflora as follows: FC = Forêt Classée, PN = Parc and L. pauciflora) belong to the group being National, RB = Réserve de la Biosphère, RNI = treated here. CAVACO also followed PERRIER DE LA Réserve Naturelle Intégrale, RS = Réserve BÂTHIE (1931) in considering L. cuspidata Baker Spéciale, and STF = Station Forestière. A full list- to be a variety of L. multiflora, whereas we resur- ing of exsiccatae for each species, with complete rect this taxon to the rank of species. localities and latitude/longitude coordinates, has Recent phylogenetic studies utilizing molecu- been compiled for the Madagascar Conspectus lar sequence data indicate that Sarcolaenaceae Project (SCHATZ et al. 1996), and is available on and Dipterocarpaceae are sister taxa within an the World Wide Web through W3 TROPICOS expanded Malvales (ALVERSON et al. 1998; (http://mobot.mobot.org/W3T/Search/vast.html). BAYER et al. 1999). Fossil pollen of Sarco- Images of selected taxa are also available on the Web laenaceae from the Miocene of South Africa at (http://www.mobot.org/MOBOT/Madagasc/ shows that the family was more widespread in sarcolae.html). Specimen data can also be the past and has become endemic to Madagascar accessed through the SONNERAT database at through extinction elsewhere (COETZEE & (http://www.mnhn.fr/base/sonnerat.html). MULLER 1984). Geographic coordinates indicated in square As in the previous papers in this series, we brackets were assigned post facto using available have re-evaluated species circumscriptions by information on Malagasy place names and examining morphological features in combina- topographic maps, compiled as a gazetteer of tion with eco-geographic parameters, including botanical collecting localities in Madagascar bioclimate (CORNET 1974; SCHATZ 2000; see (http://www.mobot.org/MOBOT/research/madagascar/ also LOWRY et al. 1997, 1998) and geological gazetteer/). substrate (DU PUY & MOAT 1996). Our analysis was facilitated by recent collections made by Malagasy students conducting field work LEPTOLAENA Thouars for their DEA studies at the Université d’Antananarivo as part of the Endemic Plant Hist. Vég. Isles Austral. Afriq. : 41, pl. 11 (1805). Families of Madagascar Project (SCHATZ et al. 2000a). TYPE.—Leptolaena multiflora Thouars. Key to the species of the Leptolaena s.s. 1.Leaves small, the largest blades usually < 2 cm long (occasionally to 4.5 cm), broadly ovate to circular or rhombic; inflorescences composed of 1-5 flowers ................................................................ 7. L. pauciflora 1’.Leaves larger, the largest blade > 3 cm long, lanceolate, obovate or narrowly to broadly ovate or elliptic; inflorescences composed of 7-50 flowers (2-8 in L. masoalensis) ................................................................ 2 2. Leaf apex obtuse to rounded, sometimes emarginate ...............................................................................