Disentangling species boundaries and phylogenetic relationships within recent evolutionary radiations is a challenge due to the poor morphological differentiation and low genetic divergence between species, frequently accompanied by phenotypic convergence, inter-specific gene flow and incomplete lineage sorting. Here we employed a genotyping-by-sequencing (GBS) approach, in combination with morphometric analyses, to investigate a small western Mediterranean clade in the flowering plant genus Linaria that radiated in the Quaternary. After confirming the morphological and genetic distinctness of eight species, we evaluated the relative performances of concatenation and coalescent methods to resolve phylogenetic relationships. Specifically, we focused on assessing the robustness of both approaches to variations in the parameter used to estimate sequence orthology (clustering threshold). Concatenation analyses suffered from strong systematic bias, as revealed by the high statistical support for multiple alternative topologies depending on clustering threshold values. By contrast, topologies produced by two coalescent-based methods (NJ_st, SVDquartets) were robust to variations in the clustering threshold. Reticulate evolution may partly explain incongruences between NJ_st, SVDquartets and concatenated trees. Integration of morphometric and coalescent-based phylogenetic results revealed (1) extensive morphological divergence associated with recent splits between geographically close or sympatric sister species, and (2) morphological convergence in geographically disjunct species. These patterns are particularly true for floral traits related to pollinator specialisation, including nectar spur length, tube width and corolla colour, suggesting pollinator-driven diversification. Given its relatively simple and inexpensive implementation, GBS is a promising technique for the phylogenetic and systematic study of recent radiations, but care must be taken to evaluate the robustness of results to variation of data assembly parameters. [Genotyping-by-sequencing; RAD-Seq; radiation; phylogeny; coalescence; concatenation; speciation; Linaria.]

The internal transcribed spacers ITS1 and ITS2 of the nuclear rDNA were sequenced for 41 Helichrysum species (Gnaphalieae), focusing on the Mediterranean group of species, together with eight representatives of other genera of the Gnaphalieae, in order to check the hypothesised monophyly of the Mediterranean Helichrysum group and the correspondence of the sequence data with its traditional sectional classification. The cladistic analysis of sequence data supports monophyly of the Mediterranean Helichrysum excluding H. frigidum and H. montelinasanum . The traditional classification of the Mediterranean species into two sections, Helichrysum and Virginea , is not supported, whereas a group constituted by species from the west Mediterranean area is shown as a moderately supported monophyletic clade in the strict consensus tree. Other results also show and confirm the complexity, still not satisfactorily resolved, of the Helichrysum generic delimitation: Pseudognaphalium luteoalbum appears merged in Helichrysum whereas Helichrysum dasyanthum appears more related to Anaxeton laeve than to any Helichrysum species.