RAD sequencing, morphometry and synecology clarify the taxonomy of the Melica ciliata (Poaceae) complex in France and Poland

Melica (Poaceae) consist of about 92 species distributed across temperate regions of the world. Within section Dalycum, Melica ciliata sensu lato forms a taxonomic complex of several species and subspecies with clinal morphological variation causing conflicting identifications. To resolve taxonomic confusion, we used three complementary approaches, through molecular, morphological, and phytoecological analyses. The double-digest restriction-associated DNA markers significantly support the monophyly of three taxa: (i) the Mediterranean Melica magnolii, (ii) the Eurasian Melica transsilvanica subsp. transsilvanica, and (iii) the west-European M. ciliata subsp. glauca. This differentiation is corroborated by the analysis of 22 morphometric variables. Furthermore, phytoecological analysis of 221 floristic inventories revealed habitat distinctions among these taxa. Our approach of integrative taxonomy argues for a specific distinction for these three taxa, and we include a key to separate these forms. These new molecular data on the section Dalycum, subsection Ciliatae, call for further phylogenetic analyses including samples of M. ciliata subsp. ciliata and other East-Mediterranean and South African taxa.