A recircumscription of Jacobsenia (Aizoaceae): Re-instating Drosanthemopsis, with two new quartz-endemics from Namaqualand, South Africa and sinking Knersia

Research reveals that the genus Jacobsenia, known for its succulent shrubs endemic to quartz-gravel patches in arid South Africa, is polyphyletic and should be recircumscribed. Phylogenetic analysis using ten chloroplast markers demonstrates that Jacobsenia vaginata does not belong in this genus but rather in Drosanthemopsis, where it is reclassified as D. vaginata. Two new species, D. bella and D. kwaganapensis, are also identified within Drosanthemopsis, both exhibiting unique antler-like epidermal cell protrusions on their leaves. Additionally, the monotypic genus Knersia is sunk into Drosanthemopsis, expanding its distribution across three phytochoria in southern Africa's quartz-field flora (QFF). The study suggests a northward diversification pattern for quartz-endemic taxa in Aizoaceae, from the Knersvlakte to the Richtersveld. Taxonomic revisions and species distributions are provided.

Klak, C., Hanáček, P., & Bruyns, P. V. (2018). A recircumscription of Jacobsenia (Aizoaceae): Re-instating Drosanthemopsis, with two new quartz-endemics from Namaqualand, South Africa and sinking Knersia. South African Journal of Botany, 116, 67–81. https://doi.org/10.1016/j.sajb.2018.02.402