Revisión taxonómica y morfológica y distribución de Zamia (Zamiaceae) en Costa Rica.

Abstract

Zamia is the third largest genus of Cycadales and the only one with native representatives in Costa Rica. All Costa Rican species inhabit rainforest undergrowth in low and mid elevation forests (up to 1100 m on the Caribbean slope and to 1600 m on the Pacific slope). Even though there have been recent revisions of the genus in other Neotropical countries, an appropriate taxonomic treatment for Costa Rican species was lacking, until Merello (2004) wrote one for the Manual de Plantas de Costa Rica. However the reality in the field and the herbaria is more complex than the one depicted by her. The main goal of this revision is to correct and update the information regarding the taxonomy of Zamia in Costa Rica. Living plants were observed in their natural habitats at 12 locations in Costa Rica. In addition, all preserved specimens from the three main herbaria of Costa Rica were examined. Vegetative characteristics such as stem color and size, leaf length, rachis length, petiole length, leaflet width and length, leaflet insertion angle, number of sporophyll rows per cone, color, length and width of the mature cone and peduncle were registered and measured. From these qualitative and quantitative data the author recognizes five species of Zamia previously recorded from Costa Rica as well as a species that is still undescribed. The species known from Costa Rica are: Zamia acuminata Oerst. ex Dyer, Z. fairchildiana L.D. Gómez, Z. gomeziana sp. ined., Z. neurophyllidia D.W Stev, Z. obliqua A. Braun and Z. pseudomonticola L.D. Gómez. The species differ in both vegetative (mostly leaflet) as well as reproductive (strobili) characters. The new species Z. gomeziana differs from Z. fairchildiana, the species which is considered most similar morphologically, in leaflet apex and size as well as in the lack of a large conic sterile megastrobilus apex. The distribution of each species is described and every known location is mapped for all species. This revision summarizes the current knowledge on the biology and habitat of all the species considered; however the ecological and demographic data are still very incomplete for most species native to Costa Rica.