Genetic and morphological variability of the endangered Syngonanthus mucugensis Giul. (Eriocaulaceae) from the Chapada Diamantina, Brazil: implications for conservation and taxonomy

Allozymic and morphometric studies were carried out on ten populations of Syngonanthus mucugensis (Eriocaulaceae), a species from north-eastern Brazil threatened by extinction. Genetic and morphological variability was low or moderately low in all populations, being lower in populations from Rio de Contas/Catolés (P_L = 14.3–21.4, A = 1.1–1.2, H_e = 0.026–0.059, D2M = 26.893–33.157) than in those from Mucugê (P_L = 28.6–35.7, A = 1.3–1.5, H_e = 0.078–0.164, D2M = 28.999–45.077). A high coefficient of endogamy (F_is = 0.257) was found, which can be explained by the reproductive characteristics and distribution of the species. The values for genetic and morphological structuring (F_st = 0.512 and A_MRPP = 0.175, respectively) were high as a result of the differentiation between populations from the two areas. The mean genetic identity between populations from the two areas (0.812) was much lower than between populations from the same area (Mucugê, 0.980; Rio de Contas/Catolés, 0.997). These results indicate that we are dealing with two distinct taxa and, as a result of the nature of the morphological differences found, a new subspecies is described for the populations of the region of Rio de Contas and Catolés, Syngonanthus mucugensis ssp. riocontensis. Such conclusions raise important implications for the conservation of Syngonanthus mucugensis, and will be used in the drawing up of management plans for its conservation. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153, 401–416.