Chusquea sect. Longiprophyllae (Poaceae: Bambusoideae): A New Andean Section and New Species

Abstract

Chusquea sect. Longiprophyllae, a group of six species of the Andean montane forests, is described as new based on the vinelike clambering habit, infravaginal branching, abaxially scabrous culm leaves, tightly circular array of subsidiary buds, central bud with an elongated prophyll, dimorphic subsidiary branches, and well developed glume II. Four new species, C. ex- asperata, C. londoniae, C. maculata, and C. longiprophylla, are described, illustrated, and their ranges mapped. Chusquea sneidernii and C. ligulata, two previously described species, are transferred to this section, and are also treated. Two keys to species are provided, one based solely on vegetative characters and the other on vegetative and flowering characters. The foliar epidermal micromor- phology of this section is described and illustrated based on a scanning electron microscopy survey of the six species. Species-specific differences were observed, and the bifurcate or branched papillae on the subsidiary cells of the stomatal apparatus and small papillae on the bulliform cells characterize the section. Chusquea Kunth is a neotropical, primarily montane bamboo genus of at least 120 species (Clark 1989). Its diversity encompasses several evolutionary lines, some of which were re- cently formally recognized as sections (Clark 1989). The sections of Chusquea are defined on the basis of modifications in the morphology of their buds, branches, foliage leaves, and to a lesser extent, inflorescences and spikelets. Re- cent field work in Colombia and Venezuela re- vealed the existence of another well defined group of species with elongated bud prophylls. In this paper, Chusquea sect. Longiprophyllae is formally recognized and described. Four new species and two previously described species comprise the section; all are described and il- lustrated, and their ranges mapped. Evidence is presented to support a monophyletic origin of this section. Because previous studies of foliar epidermal micromorphology demonstrated taxonomically useful patterns of variation within Chusquea (Clark 1986), a scanning electron microscopy (SEM) survey of the foliage leaves of the species of this section was conducted.