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The genus Daucus is widely distributed worldwide, but with a concentration of diversity in the Mediterranean Region. The D. carota complex presents the greatest taxonomic problems in the genus. We focus on a distinctive phenotypic group of coastal morphotypes of D. carota, strictly confined to the margins to within about 0.5 km of the Mediterranean Sea and the Atlantic Ocean, which we here refer to as coastal morphotypes or D. carota subsp. “gummifer” complex. They are loosely morphologically coherent, sharing a relatively short stature, thick, broad, sometimes highly glossy leaf segments, and usually flat or convex fruiting umbels. We analyzed 288 accessions obtained from genebanks in England, France, and the USA, and an expedition to Spain in 2016, covering the Mediterranean and Atlantic coasts and Balearic Islands, where much of the gummifer complex variation occurs. Our study includes 112 accessions not examined before in this context. Genotyping-by-sequencing identified 29,041 filtered SNPs. Based on high bootstrap support from maximum likelihood and Structure analysis we highlight three main clades. The gummifer morphotypes are intercalated with members of Daucus carota subspecies carota and subspecies maximus in two of these main clades, including a clade containing accessions from Tunisia (also including D. carota subsp. capillifolius) and a clade containing accessions from western Europe (including the British Isles), southern Europe (including the Balearic Islands and the Iberian Peninsula) and Morocco. These results support five independent selections of the gummifer morphotypes in these restricted maritime environments in the Mediterranean and nearby Atlantic coasts. Daucus annuus (=Tornabenea annua) and Daucus tenuissimus (=Tornabenea tenuissima) also fall firmly within D. carota, supporting their classification as morphologically well-defined subspecies of D. carota, which are accepted here under the new combinations Daucus carota subsp. annuus and D.

In a previous study using 94 nuclear orthologs, we reported the species status of the Daucus guttatus complex to be unresolved, partitioned into three clades. In the present study, a subset of ten of these 94 orthologs was used to infer the phylogeny of the D. guttatus complex and related species. A near parallel set of accessions, planted in a common garden, was used for morphological analyses. The molecular trees are highly resolved for most of the clades, grouping accessions of the D. guttatus complex into four clades. Bayesian concordance analysis and a coalescent approach gave slightly different topologies. Morphological data likewise support four taxa in the complex. Moreover, herbarium research from a companion study informs nomenclature for taxa of the complex. We identify these four clades as D. bicolor, D. conchitae, D. guttatus, and D. setulosus; internested in or among these segregates are the phenetically distinctive species D. glochidiatus, D. involucratus, D. littoralis, and D. pusillus. Our research redefines species variation in the D. guttatus complex, clarifies species names, interspecific relationships, confirms a useful subset of nuclear orthologs for studies of dominant topologies of Daucus, and discovers morphological characters allowing proper identification of the four species of the D. guttatus complex and related species.

The Daucus guttatus complex includes two to four species growing from central and northern Italy to the Middle East. They are characterized by being typically annuals up to 50 cm high; with primary umbels up to 7 cm in diameter with fewer than 25(35) rays; discolored umbels frequent, bearing one to several dark colored umbellules which form different color patterns; and mericarps relatively small, ca. 2.0‐4.5 mm. The taxonomy of this complicated group has not been satisfactorily resolved to date and is the focus of current research. Seven names of species belonging to the D. guttatus complex occurring in the central and eastern Mediterranean basin are typified here: Daucus guttatus, Daucus bicolor, Daucus involucratus, Daucus setulosus, Daucus broteri, Daucus hirsutus, and Daucus speciosus. Historical data are reported to justify lectotype and/or epitype selection, and selected morphological and distributional data are used to facilitate identification. The resulting typifications will enable proper naming of clades identified in the accompanying integrated molecular and morphological study, clarifying the taxonomy of the Daucus guttatus complex.