Geographic Variation in a Widespread Neotropical Species, Mouriri myrtilloides (Melastomataceae)

Abstract

Geographic variation inMouriri myrtilloides (Swartz) Poiret is analyzed on a morphological basis. Plants from Central America have medium puberulence, long calyx lobes, and short petioles and pedicels; those from Jamaica and Haiti are glabrous and have short calyx lobes, petioles, and pedicels; while those from Cuba have maximum puberulence, medium calyx lobes and pedicels, and long petioles. Glabrous or near-glabrous plants also appear rarely and more or less at random in Central and South America. Distribution in South America is limited to the northwest quarter of the continent. Most plants of this region are similar to those of Central America except that they have slightly shorter calyx lobes. However, the very short calyx lobes of plants from Jamaica and Haiti often occur in South America and rarely in Panama. Furthermore, most features of the Cuban plants appear in those of the Orinoco Basin, while individuals with one of these features, strong puberulence, are occasional elsewhere in South America. It is suggested that the complex originated in northwest South America and diversified there, subsequently radiating north and west. Considerations and problems related to such a dispersal are discussed. Taxonomically the complex is treated as consisting of four subspecies: ssp.parvifolia of Central America and much of the north-west quarter of South America, ssp.myrtilloides of Jamaica and southwest Haiti, ssp.acuta of Cuba, and ssp.orinocensis of the Orinoco Basin, the latter being a new taxon.