SYSTEMATIC REVISION OF THE CENTRAL AMERICAN SPECIES OF THE GENUS BEGONIA SECT. GIREOUDIA

Begonia sect. Gireoudia is the largest of 14 Begonia sections occurring in Central America. It is a phentically related group of species that can be differentiated from other sections by plant habit coupled with floral morphology. Of the 27 species herein recognized from Central America, 16 are endemic to the region, largely to Costa Rica and Panama where they range from sea level to over 2000 m elevation. The need for an intensive systematic study of the section became apparent during attempts to identify species from southern Central America with available floristic treatments.; During the latter part of a three year residence in Costa Rica and a subsequent trip to Costa Rica and Panama, species within sect. Gireoudia were collected intensively and field observations were made. This material and information combined with over 2500 herbarium specimens has permitted a re-evaluation of species within sect. Gireoudia. Five new species are presently recognized among the 27 species in sect. Gireoudia that occur in Central America; of these, four are Panamaian and one is Guatemalan. Two widely ranging and frequently collected taxa, B. sericoneura and B. urophylla have been reinterpreted as a result of this research, while two additional species, B. broussonetiifolia and B. cardiocarpa which were treated in synonomy in recent floras are recognized as distinct. Accompanying this treatment are in depth discussions of the morphological characters that are important in distinguishing among species in sect. Gireoudia and illustrations of major floral and vegetative characters. A detailed key to the Central American species in the section is included in this treatment. Each species is accompanied by a thorough description of its morphological features along with a discussion of its relationships to other taxa in the section. Tables were prepared to compare phenetically similar taxa and distribution maps are included for all the species. New species are illustrated with line drawings. Species were divided into 12 species complexes based upon morphological similarities among taxa.