Pentziinae Oberpr. & Himmelr.

Oberprieler, Christoph, Töpfer, Alisha, Dorfner, Marco, Stock, Miriam & Vogt, Robert, 2022, An updated subtribal classification of Compositae tribe Anthemideae based on extended phylogenetic reconstructions, Willdenowia 52 (1), pp. 117-149 : 127

7. Pentziinae Oberpr. & Himmelr. in Willdenowia 37: 99. 2007. – Type: Pentzia Thunb. ( Pentzia crenata Thunb. , nom. illeg.).

Description — Shrubs, subshrubs or perennial to annual herbs. Indumentum of basifixed hairs or absent, rarely of medifixed hairs ( Pentzia ). Leaves alternate or rarely opposite ( Pentzia , Rennera ), entire, lobed or 1- or 2-pinnatisect. Capitula solitary or in corymbs, rarely closely aggregated ( Marasmodes ), discoid or disciform, sometimes radiate ( Cymbopappus , Foveolina , Oncosiphon ). Involucre hemispheric to cylindric, sometimes urceolate ( Marasmodes ). Phyllaries in 3–5 rows, with or without scarious margins. Receptacle flat or convex to conic, epaleate. Ray florets female; limb white or pinkish. Disc florets hermaphrodite; corolla 4- or 5-lobed, sometimes tube swollen and brittle ( Oncosiphon ) or with thick vascular strands ( Cymbopappus , Marasmodes , Pentzia ); anthers with non-polarized endothecial tissue and a slender filament collar. Achenes oblong to obovoid, with 4- or 5 ribs, sometimes triquetrous in cross-section and with 1 adaxial and 2 lateral ribs ( Myxopappus ); apex marginally rounded, with an entire or toothed rim, an oblique, adaxially longer, entire corona, a corona of 3–10 scales or with a large adaxial and a smaller abaxial scale; pericarp sometimes spongy ( Myxopappus ), with myxogenic cells on ribs and abaxial surface, without resin sacs, rarely without myxogenic cells ( Oncosiphon , Rennera ). Embryo sac development monosporic (only known in Oncosiphon ). Base chromosome number x = 6, 7, 8, 9.

Distribution — South Africa, Lesotho, Namibia, Botswana, Morocco, Algeria, Chad, Somalia, Yemen.

Members — Cymbopappus B. Nord. (3), Foveolina Källersjö (5), Marasmodes DC. (13), Myxopappus Källersjö (2), Oncosiphon Källersjö (8), Pentzia Thunb. (27, incl. Rennera Merxm. ).

Notes — While in the analysis based on concatenated sequences the subtribe Pentziinae received strong support for being monophyletic ( Fig. 3), this signal is less clear in the other phylogenetic reconstructions. In the tree based on cpDNA sequence variation, a monophyletic Pentziinae is found comprising also the representative of Mausolea from the Artemisiinae (Fig. 1), while in the nrDNA tree ( Fig. 2) only a group excluding Myxopappus receives strong support, and in the coalescent-based species tree ( Fig. 4) a strongly supported relationship with subtribe Cotulinae emerged. These equivocal circumscriptions and relationships may be a consequence of either hybridization events or incomplete lineage sorting connected with the intermediary role of the Pentziinae in biogeographical respects between the S hemispherebased subtribes on the one hand and the Asian-based subtribes Artemisiinae and Handeliinae on the other. This is additionally supported by the occurrence of some species of Pentzia in N Africa and SW Asia ( Oberprieler & al. 2007).

Delimitation of genera in the Pentziinae is highly problematic. Phylogenetic analyses based on nrDNA ITS and cpDNA markers by Magee & al. (2015) revealed considerable discrepancies between tree topologies based on the two datasets with little support for the monophyly of the hitherto accepted genera; exceptions being Marasomodes (well supported by both datasets), Myxopappus (supported in the cpDNA tree) and Rennera (well supported by both datasets but nested in a paraphyletic genus Pentzia ). Except for the transfer of the four Rennera species to Pentzia proposed by Magee & al. (2015), no further nomenclatural consequences were drawn from the mentioned analyses, and a further discussion of generic limits in this subtribe must await more comprehensive genetic/genomic datasets and analyses. However, due to the extremely productive revisionary work of A. R. Magee (Compton Herbarium, Cape Town, South Africa) and his collaborators, the taxonomy of some genera is now well understood ( Marasmodes, Magee & al. 2017 ; Oncosiphon, Kolokoto & Magee 2018 ; the Pentzia incana group, Magee & Tilney 2012).