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Abstract

A new species, Caloglossa apomeiotica West et Zuccarello, is described based on material from San Carlos, Bahia Magdalena, Bajo California Sur. The species is morphologically similar to C. leprieurii but characterised by the production of bisporangia and, less commonly, tetrasporangia, and the lack of sexually reproducing plants. In eight culture isolates from throughout the geographic range of the species only the bisporangia were viable. The present known distribution of Caloglossa apomeiotica is from Bahia Magdalena, Baja California Sur to Barra de Navidad, Jalisco in Pacific Mexico. It is suggested that C. apomeiotica is derived from C. leprieurii populations further south in the Americas through a loss of sexual reproduction. Based on our field collections in March, 1993 the nearest populations of sexually reproducing C. leprieurii are 1200 kin away in Estero las Garzas, Chiapas, Mexico and extend south into Guatemala.