Fig 1.
Natural habitat of Oberholzeria etendekaensis.
Plants of O. etendekaensis in their natural habitat (low-growing shrublets in foreground), Etendeka Mountains, Namibia. The plants grow in stony soil and scree derived from basalt of the Etendeka Group, Karoo Supergroup. This section of the Great Escarpment lies to the east of the Namib Desert, about 50 km from the Atlantic Ocean coastline. The climate is very arid, with an average annual rainfall of about 100 mm. Photo: W. Swanepoel.
Fig 2.
Geographical distribution of Oberholzeria etendekaensis.
Topographic map of southern Africa showing the known distribution of O. etendekaensis (black square) in the far north-western corner of Namibia. The locality falls within the Kaokoveld Centre of Endemism, a biogeographical region rich in restricted-range plants and animals. The new species is known from a single population comprising two small subpopulations growing about 500 m apart in the Etendeka Mountains. These mountains form part of the Great Escarpment of southern Africa. Neighbouring countries indicated by numbers, namely Angola (1), Zambia (2), Botswana (3), Zimbabwe (4), Mozambique (5), South Africa (6), Swaziland (7) and Lesotho (8).
Fig 3.
Phylogenetic tree based on nrDNA ITS sequences.
Phylogenetic relationship of Oberholzeria etendekaensis (arrowed) derived from maximum parsimony analysis of the nrDNA ITS sequences; 109 taxa, 740 total characters with 639 included, of which 330 (52%) were parsimony informative. Tree shown is strict consensus of >100,000 equally most parsimonious trees of 1784 steps. Numbers represent maximum parsimony bootstrap support values (100–500 replicates) greater than 70% for selected clades; thickened branches represent clades with Bayesian posterior probabilities greater than 0.95. Oberholzeria is supported as the sister to a clade comprised of tribes Crotalarieae and Genisteae (76% and 1.0, respectively).
Fig 4.
Phylogenetic tree based on plastid matK gene sequences.
Phylogenetic relationship of Oberholzeria etendekaensis (arrowed) derived from maximum parsimony analysis of the plastid matK gene sequences; 74 taxa, 1572 total characters with 1518 included, of which 456 (30%) were parsimony informative. Tree shown is strict consensus of 794 equally most parsimonious trees of 1076 steps. Numbers represent maximum parsimony bootstrap support values (500 replicates) greater than 70% for selected clades; thickened branches represent clades with Bayesian posterior probabilities greater than 0.95. Both bootstrap and Bayesian analyses strongly support Oberholzeria as the sister group to the Genisteae clade (100% and 1.0, respectively).
Table 1.
Summary of the statistics of the phylogenetic analyses that were conducted on both the ITS and matK datasets.
Fig 5.
Flower morphology of Oberholzeria etendekaensis.
Line drawings depicting the flower morphology. (A) Bract. (B) Calyx, opened out; lobes equal, dorsiventrally flattened. (C) Standard; strongly reflexed in the intact flower and lacking callosities. (D) Wing petal; longer than the keel and without a spur. (E) Keel petal. (F) Androecium, opened out; diagnostic for the genus is the stamens which are all fused into a tube that is closed above, and dimorphic anthers with five long, basifixed anthers alternating with five short, dorsifixed anthers. (G) Gynoecium. Voucher: Swanepoel 316 (WIND). Artist: M.M. le Roux.
Fig 6.
Habit and macromorphology of Oberholzeria etendekaensis.
Photographs illustrating the morphology of the plants. (A) Flowers with rostrate keels, reflexed standards, paired dark-brown spots at the bottom of the standard blades and dorsiventrally flattened, equally 5-lobed calyces. (B) Laterally flattened and somewhat inflated fruit. (C) Succulent stem. (D) Leaf-opposed inflorescences and pinnately trifoliolate leaves. (E) Habit; biennial or short-lived perennial succulent shrublet. Photos: W. Swanepoel.
Table 2.
Prominent differences between Oberholzeria and the early divergent genera from both the tribes Genisteae (Dichilus and Melolobium) and Crotalarieae (Euchlora, Bolusia and Crotalaria).