A New Species of Ardisia (Myrsinaceae) from Madagascar

Abstract

Recent exploration in the Marojejy Natural Reserve has resulted in the discovery of a new species, Ardisia (subg. Akosmos) marojejyensis. The species is described and illustrated, and its phylogenetic relationships are discussed. A key to distinguish the three known Madagascan species of Ardisia is provided, and subgenus Madardisia is relegated to synonymy under subgenus Akosmos. The Reserve Naturelle Integrale de Marojejy (number 12) comprises 60,150 hectares of wet, tropical forests that range from ca. 100 to 2,137 m in elevation (Jenkins, 1987). Henri Humbert botanized extensively in the region and made approximately 3,000 collections, many of which were species new to science (Humbert, 1955). Humbert's efforts were undoubtedly one of the factors drawing interest to the rich, largely endemic flora and leading to the declaration of the area as a reserve in 1952. Despite the efforts of Humbert and botanists who have since continued collecting in the reserve, the flora remains poorly known and continues to yield novelties. Recent estimates (Miller, ined.) indicate that the flora of the reserve contains about 2,000 species, perhaps 20% of the total flora of the country. Collecting efforts in the southern part of the reserve in February 1989 have yielded a previously undescribed species of Ardisia Swartz (Myrsinaceae), only the third reported for Madagascar. Ardisia (subg. Akosmos) marojejyensis James S. Miller & Pipoly, sp. nov. TYPE: Madagascar. Antsiranana: Reserve Naturelle Integrale de Marojejy, along the trail to the summit of Marojejy Est, NW of Mandena, wet, evergreen forest above the second camp, 700-850 m, 14?26'S, 49?16'E, 10 Feb. 1989 (fl), James S. Miller & P. P. Lowry 3936 (holoytpe, MO 4064879; isotypes, K, P, TAN, US). Figure 1. Arbor ad 15 m alta. Folia persistentia; lamina obovata, 18-28 cm longa, 8-12 cm lata, apice late obtuso ad rotundato, basi cuneata ad obtusa; petiolo 3-5 cm longo. Flores pedicellis 1-2 mm longis inserti, sepalis 1.7-2 mm longis, petalis 4-5 mm longis, antheris 2.5-3 mm longis, stylo ca. 3 mm longo. Fructus nobis non visus. Tree 10-15 m tall; branchlets terete, 1-1.5 cm diam., densely furfuraceous-lepidote, the scales so densely packed as to form an apparent sheet, later breaking up and somewhat glabrescent. Leaves persistent; lamina carnose when fresh, drying coriaceous, obovate, 18-28 cm long, 8-12 cm wide, the apex widely obtuse to rounded, the base cuneate to obtuse, decurrent on the petiole, midrib depressed above, prominently raised and black punctate-lineate below, the secondary veins 35-40 pairs, 0.51 cm apart, inconspicuously pellucid punctate, glabrous above and below; petiole marginate, 3-5 cm long, densely furfuraceous-lepidote, glabrescent. Inflorescences clustered near the apices of branches, internodal, erect, paniculate, the rachis 15-30 cm long, the lateral branches 5-10 cm long, glabrous or nearly so. Flowers bisexual, borne on pedicels 12 mm long; buds ovoid to conical; sepals 5, quincuncial, greenish white, ovate, 1.7-2 mm long, glabrous, sparsely pellucid punctate, the margin scari us, hyaline, glabrous; petals 5, quincuncial, bright pink, basally connate, ovate to narrowly ovate, 45 mm long, 1.5-2 mm wide, apex acute, symmetric, prominently pellucid punctate, the margin irregular, entire, glabrous; stamens 5, the filaments 0.2-0.4 mm long, basally adnate to the petals, free from each other, the anthers bright yellow, lanceoloid, 2.5-3 mm long, apex long-apiculate, base cordate, dehiscing first by apical pores, then narrow, longitudinal slits, the connective conspicuously brown punctate dorsally; ovary ovoid, 0.5-1 mm long, the placenta depressed-globose, 0.4-0.6 mm long, 0.60.8 mm diam., apex apiculate, the ovules 4, biseriate, the style ca. 3 mm long, the stigma punctiform. Fruit unknown. Local names: Talandoha (near Mandena); Maimbola (Ambatosoratra). Ardisia marojejyensis is a spectacular, apparently mass-flowering tree, covered with pink flowers, making it easily visible from a distance. It is uncommon in the reserve at middle elevations, and few individuals were seen even though all in a given valley can easily be counted. Because this species appears to mass flower (all individuals flower synchronously in a short period of time), it is probable that it has been missed by previous collectors purely NOVON 3: 63-65. 1993. This content downloaded from 157.55.39.208 on Fri, 14 Oct 2016 04:16:46 UTC All use subject to http://about.jstor.org/terms