The biology and systematics of the genus Coincya Porta & Rigo ex Rouy (Cruciferae)

In this treatment, the genera Coincya (synonym: Hutera) and Rhynchosinapis are regarded as one genus under the name Coincya which has nomenclatural priority. This study is based on data from morphology, population studies, cytology, ecology and reproductive biology reinforced by breeding experiments.Coincya is a west European genus comprising 14 taxa (including six species, five subspecies and three varieties).Eight new combinations are proposed and two species are excluded; R.nivalis is referable to the genus Brassica and R. Leplocarpa is probably referable to Erucastrum. The chromosome number is either 2n= 24 or 2n= 48, which confirmed previous counts; C. Transtagana has not been counted. Breeding experiments were carried out with C. Longirostra, C.rupestris, C.monensis subsp.monensis, diploid and tetraploid races of subsp.recurvata var.recurvata, var.johnslonii, var.setigera, var.granatensis, subsp.hispida and subsp.puberula. All taxa tested are outbreeding with a genetic self-incompatibility mechanism and are cross-compatible, suggesting that there has been no cytological differentiation between the diploid species in this study. The tetraploids formed semi-sterile triploids when crossed with diploids and although the chromosomes only formed bivalents and trivalents at meiosis it was postulated that the tetraploid was an autotetraploid of polytopic origin. The evolution and differentiation of the genus and species are discussed.