Four New Species of Hedyosmum (Chloranthaceae) from South America

Abstract

Four new species of Hedyosmum subg. Tafalla are described from the montane forests of Andean South America. Three, H. spectabile, H. steinii, and H. anisodorum, belong to sect. Microcarpa, while H. luteynii is in sect. Macrocarpa. The genus Hedyosmum Swartz consists of about 40 species of mainly montane Neotropical shrubs and trees. Species are found from southern Mexico to Panama, and in Venezuela, Colombia, Ecuador, Peru, Bolivia, Brazil, and Paraguay, as well as the West Indies. One species occurs in the Far East. The center of diversity of the genus is in the wet, northern Andes where three-fourths of the species are located. A recent monographic study (Todzia 1986) revealed several new species from this area. Previous study of the genus in the northern Andes is scant. Solms-Laubach (1869) recognized 12 species in the area in the only comprehensive monograph of the genus to date. Cuatrecasas (1945) circumscribed seven additional species from Colombia. In Peru, Macbride (1931, 1937) recognized seven species including two newly described taxa. A key to the species of Hedyosmum will be presented in a forthcoming monograph (Todzia, in press). All four species described here are members of Hedyosmum subg. Tafalla (Ruiz Lopez & Pav6n) Solms-Laubach, which is characterized by fleshy floral bracts subtending the pistillate flowers. These floral bracts are connate to various degrees forming clusters of flowers termed cymules and at maturity become white or purple. These new species belong to two different sections, sect. Microcarpa Solms-Laubach and sect. Macrocarpa Solms-Laubach. They differ in that sect. Microcarpa has pistillate inflorescences of racemes or panicles usually with more than 4 cymules, and floral bracts that are separate or at least distinguishable; sect. Macrocarpa has pistillate inflorescences composed of 1-3 cymules and floral bracts that are completely fused at flowering. Also, the fruiting cymules of sect. Microcarpa are usually white, seldom purple, while those of sect. Macrocarpa are always dark purple. The distinguishing characteristics of these four new species are presented in table 1. Hedyosmum spectabile Todzia, sp. nov. (fig. 1).-TYPE: Peru, San Martin: Puente Rio Nieva, limite Amazonas-San Martin Departments, km 102 W of Rioja, 2000 m, 16 Feb 1985 (pist), C. A. Todzia & B. A. Stein 2700 (holotype: TEX!; isotypes: AAU!, F!, GH!, MO!, NY!, US!, USM!). Arbores vel frutices unisexuales 3-7 m alti, laminae foliorum ellipticae vel ovatae acuminatae rigidae erectae supra glabrae subtus villosae, vaginae echinatae, inflorescentiae staminatae in 1-2 paribus oppositis portatae, connectivis compressis 0.5-1.0 mm longis apicibus acutis erectis, inflorescentiae pistillatae racemosae vel paniculatae fasciculis 2-4(6)-floribus brevipedunculatis; monas dispersalis albae. Unisexual, aromatic small trees or shrubs 37 m tall, trunk ca. 7-8 cm dbh, with prop roots; wood white, weak, when cut turning orange and exuding brown mucilage; stems terete, strigose to hispid, often purple, encircled at nodes by persistent leaf-sheaths; internodes 7-10 cm long; nodes swollen. Leaf blades pungently aromatic, elliptic to ovate, (6.5)10-20 cm long, (2.5)5-8 cm wide, terminating with acuminate tips 0.5-1.2 cm long, cuneate to rounded at base, stiff and coriaceous, erect, upper surface smooth and glabrous, dull and drying light brown, lower surface reddish brown, villous with brown to whitish brown hairs, margins serrulate with sharp teeth 1.0-1.5 mm distant, midveins impressed on upper surface, raised and villous on lower surface; larger lateral veins 9-11 on each side, 9-14 mm distant, uniformly arcuate, drying impressed above, raised below, with smaller intersecondary veins extending ca. 1/2 distance to