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<i>Microcnemum coralloides</i> (Chenopodiaceae- Salicornioideae): an example of intraspecific East-West disjunctions in the Mediterranean region

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Kadereit, G. & A.E. Yaprak. 2008. Microcnemum coralloides (Chenopodiaceae-Salicornioideae): an example of intraspecific East-West disjunctions in the Mediterranean region. Anales Jard. Bot. Madrid 65(2): 415-426. Microcnemum is a monotypic genus of Salicornioideae comprising rare, annual, hygrohalophytic herbs growing in hypersaline inland lagoons and salt pans. Microcnemum coralloides shows an East-West disjunction in the Mediterranean region: M. coralloides subsp. coralloides occurs in central and eastern Spain while M. coralloides subsp. anatolicum grows in Turkey, Syria, Armenia and Iran. We studied the phylogeny, biogeography and morphological differentiation of M. coralloides. Molecular analyses, using five western and eight eastern accessions of the species, were based on three different markers (nuclear ITS and plastid atpB-rbcL spacer and trnT/F region) analysed with Maximum Parsimony and Maximum Likelihood. Estimates of divergence times were calculated using a Likelihood Ratio Test (LRT) and the Penalized Likelihood (PL) method. The two subspecies can be clearly distinguished by their different seed testa surface. Other diagnostic characters were not found. The molecular data (ITS and ML analysis of the trnT/F region) indicate that M. coralloides subsp. coralloides originated from within M. coralloides subsp. anatolicum which implies an East Mediterranean origin and subsequent westward dispersal. Age estimates for the split of the two subspecies range from 2.8–0.5 million years ago. Considering the relatively low genetic differentiation and the low crown group age (0.7–0.1 mya) of M. coralloides subsp. coralloides in comparison to M. coralloides subsp. anatolicum we favour the hypothesis that the Iberian part of the species range was established during cold periods of the Early Pleistocene and that the range of the species was fragmented during a warmer period soon after its arrival in Iberia.