Born in the Mediterranean: Comprehensive Taxonomic Revision of Biscutella ser. Biscutella (Brassicaceae) Based on Morphological and Phylogenetic Data

Abstract

<jats:p>Biscutella L. ser. Biscutella (= Biscutella ser. Lyratae Malin.) comprises mostly annual or short-lived perennial plants occurring in the Mediterranean basin and the Middle East, which exhibit some diagnostic floral features. Taxa in the series have considerable morphological plasticity, which is not well correlated with clear geographic or ecologic patterns. Traditional taxonomic accounts have focused on a number of vegetative and floral characters that have proved to be highly variable, a fact that contributed to taxonomic inflation mostly in northern Africa. A detailed study and re-evaluation of morphological characters, together with recent phylogenetic data based on concatenation of two plastid and one nuclear region sequence data, yielded the basis for a taxonomic reappraisal of the series. In this respect, a new comprehensive integrative taxonomic arrangement for Biscutella ser. Biscutella is presented in which 10 taxa are accepted, namely seven species and three additional varieties. The name B. eriocarpa DC. is reinterpreted and suggested to include the highest morphological variation found in northern Morocco. Its treatment here accepts two varieties, one of which is described as new (B. eriocarpa var. riphaea A. Vicente, M. Á. Alonso &amp; M. B. Crespo). In addition, the circumscriptions of several species, such as B. boetica Boiss. &amp; Reut., B. didyma L., B. lyrata L., and B. maritima Ten., are revisited. Nomenclatural types, synonymy, brief descriptions, cytogenetic data, conservation status, distribution maps, and identification keys are included for the accepted taxa, with seven lectotypes and one epitype being designated here.</jats:p>

Diversification of Biscutella ser. Biscutella (Brassicaceae) followed post-Miocene geologic and climatic changes in the Mediterranean basin

“…Most characters often used to arrange the series have revealed not always diagnostic for taxonomy since they are highly variable even in a single population (cf. Vicente et al, 2019b). Combination of both morphological and molecular data reveals promising for new insights on the specific limits and taxonomic arrangement of taxa in the series (cf.…”

“…Over 800 herbarium vouchers were visually examined (see Vicente et al, 2019b), and both qualitative and quantitative analyses were conducted on over 600 of those specimens. The characters observed or measured (Table 2) were selected from those traditionally used in the literature on the genus (Jordan, 1864;Poiret, 1789;Malinowski, 1911;Guinea, 1964;Maire, 1967).…”

“…For a more detailed description of materials and methods used for previous morphological studies undertaken on B. ser. Biscutella see Vicente et al (2019b). Author names of taxa cited in the text and tables accord with IPNI (2019).…”

“…Relatively morphological homogeneity can be observed in C-E Mediterranean basin to SW Asia where B. didyma L. is mostly distributed, whereas the highest morphological plasticity and diversity occurs in N Africa with up to five species (cf. Vicente et al, 2016Vicente et al, , 2019aVicente et al, , 2019b.…”

“…A recent comprehensive revision of B. ser. Biscutella (Vicente et al, 2019b), including a reevaluation of morphological characters, has reduced its diversity to ten taxa (7 species and 3 varieties) exhibiting distinct morphologies and well-defined distributions and/or ecology, which in several cases have proved to be monophyletic groups (cf. Vicente et al, 2016Vicente et al, , 2019a.…”