New Taxa and Nomenclatural Notes on the Flora of the Marojejy Massif, Madagascar: I. Capparaceae: A New Species of Crateva

Abstract

A new species of Crateva L. is described from the Marojejy Massif in northeast Madagascar. It differs from previously described species in having simple obovate leaves with a rounded apex. The species is deciduous and flowers soon after the leaves emerge, indicating that it is a member of section Siccoruba Jacobs. The Marojejy Massif is an isolated upland area in northeastern Madagascar in the province of Antsiranana. Located between Andapa, to the west, and Sambava, to the east, the massif rises out of undulating lowlands to a vast upland area mostly above 800 m to its highest point at 2137 m, Marojejy Est. It is bounded by the valleys of the Androranga River on the north and the Lokoho River on the south. Marojejy is the easternmost of the satellite upland regions that surround Tsaratanana, which lies approximately 100 km to the northwest and at 2876 m is the center of the northern highlands. The upland areas that occur in closest proximity to Marojejy include Betsomanga (ca. 1250 m) ca. 25 km to the north, Andramanalana (2260 m) 40 km to the west, and For&t D'Anjanaharibe (ca. 1850 m) ca. 40 km to the southwest. A large number of endemic taxa have been reported from Marojejy (Humbert, 1955), but it is unclear what percentage of these also occur on the scattered peaks between Marojejy and Tsaratanana, as most remain very poorly explored. The central portion of the massif and some of the surrounding lowland areas comprise a 50,000-ha protected area, the Reserve Int6grale No. 12, which was established 31 December 1927. The massif consists mostly of uplifted gneiss, and the topography is extremely rugged with numerous peaks in the reserve above 1500 m. Marojejy and the Foret d'Anjanaharibe comprise most of the watershed for the Andapa region, one of Madagascar's most important rice-producing areas. Prevailing winds come from the southeast, and the northern portion of the reserve is somewhat drier than the southern and eastern flanks of the massif. The lowland portions of the reserve consist of a mosaic of evergreen tropical forest, with a canopy 30--60 m tall and secondary growth in areas of cyclone disturbance dominated by Afromomum angustifolium K. Schumann and several species of bamboo. The steep slopes of the central massif between 500 and 1000 m are also mostly forested, except for exposed areas of gneiss and the most extreme slopes. Above 1000 m, a variety of vegetation types occur, depending on slope, exposure, and depth of soil. More sheltered valleys are covered with wet, medium-height forest (the sylve d lichens of Humbert, 1955), whereas wind-swept ridges below about 1700 m have a dense cover of shrubs and occasional trees to 5 m. The uppermost reaches of the numerous peaks have an open, primarily herbaceous vegetation with numerous Cyperaceae, Poaceae, and Orchidaceae and scattered patches of shrubs up to about a meter tall primarily composed of Rubiaceae, Ericaceae, and Symphonia microphylla (Cambessades) Bentham & Hooker ex Vesque (Clusiaceae). Henri Humbert collected intensively in the area from 1948 to 1950, discovering many new taxa and clearly demonstrating that the massif is a center of endemism within northeastern Madagascar (Humbert, 1955). However, Humbert's published accounts of his collecting were not comprehensive, and the author began a new effort to inventory the region thoroughly with four collecting trips in 1988 and 1989. Since that time intensive collecting has continued, and the results will be summarized in a checklist of the Marojejy Massif (Miller, Rakotomalaza, Raharilala, and Rakotondrainibe, in prep.). These recent efforts have yielded many new discoveries that will be named in this series, although a species of Ardisia Swartz (Myrsinaceae) has been previously published based on these collections (Miller & Pipoly, 1993). The genus Crateva L. (see G6mez, 1953, for notes on the correct orthography of the generic name) consists of eight species widely distributed in the tropics (Jacobs, 1964), with three reported from Madagascar. Although Hadj Moustapha (1965) recognized four species, Jacobs (1964) pointed out that Crateva humblotii (Baillon) Hadj-Moustapha was a confused name robably based on Capparis humblottii Baillon and specimens referable to C. excelsa Bojer and C. obovNovoN 8: 167-169. 1998. This content downloaded from 207.46.13.131 on Sat, 15 Oct 2016 04:19:22 UTC All use subject to http://about.jstor.org/terms