Mosses of the Yucatan Peninsula, Mexico. III Phytogeography

Abstract

There are 69 species and varieties of mosses reported for the Mexican part of the Yucatan Peninsula. These can be grouped into five floristic elements; the Caribbean element with 46 species indicates a close relationship of the peninsular flora with that of the West Indies. The endemic element is virtually absent. In Mexico the distribution of the peninsular flora includes the eastern and western coastal areas, ranging up to the Neovolcanic Belt in the center. This is similar to the distribution of characteristic area climates and vascular plant vegetation. There is no pen- insular effect evident in this area perhaps because of continued floristic exchange with mainland Mexico and the West Indies. The small size of the flora may be the result of intense human activity correlated with an undulating topography, absence of surface waterways, rapid drainage of rainfall and reduced number of microhabitats. Field work in the Mexican states of Campeche, Yucatan and Quintana Roo over a period of years has resulted in a collection of about 600 specimens. These have been studied to determine number of species and moss distribution in the Yucatan Pen- insula. The list of species was given in two preceding publications (Delgadillo, Cairdenas & Sharp 1982; Delgadillo & Cardenas 1982) and included 69 species and varieties. However, the information derived from this research requires further analysis to clarify the significance of moss distribution in the Yucatan Peninsula and update an earlier analysis (Steere 1935).