An integrative taxonomic revision of the Chaerophyllum hirsutum complex using morphological and molecular markers. Chaerophyllum taxonomic revision

Background and aims – Chaerophyllum hirsutum represents a complex of taxa with varying treatments and ranks across floras. Using both morphometric and molecular markers, we assessed the robustness of C. hirsutum var. hirsutum, C. elegans, C. villarsii and C. villarsii var. cicutariaeforme. Material and methods – Ten morphometric variables and two ratios were estimated. Based on the sequencing of six plastomes, we selected the RPS16 as the more variable region, sequenced on a broader sampling. Finally, we also sequenced the nrDNA internal transcribed spacer 2 (ITS2) amplicon using Illumina technology to obtain intra-individual allelic diversity. Key results – Morphologically, the most easily differentiated taxon was C. elegans, especially using phyllotaxy. The distinction between var. hirsutum and var. villarsii is rather clinal, but mainly based on the degree of carpophore division. Finally, var. cicutariaeforme is less easily distinguishable from the three others, but partly using the carpophore length and the total length of basal leaf blade. The cpDNA RPS16 clearly distinguish C. elegans from the three other taxa of C. hirsutum, which rather show a geographical pattern of cpDNA diversity. The nrDNA ITS2 partially distinguish var. villarsii from the other taxa, without distinction of C. elegans. Conclusions – The present study supports the species differentiation of C. elegans based on both morphology and chloroplast genome. We have opted to gather var. villarsii and var. cicutariaeforme within C. hirsutum until further studies reinvestigating these taxa with more resolving markers covering a broader part of the nuclear genome.