Polygala kalaboensis Paiva

Paiva J. & Barrios S. 2016. Polygala kalaboensis (Polygalaceae), a new species from Zambia. Kew Bulletin 71:10. DOI 10.1007/S12225-016-9616-Y

Morphology Leaves

Leaves alternate, petiole 0.5 - 1 mm, glabrous, lamina obovate-oblong to spathulate-oblong, 1.5 - 2.5 x 0.4 - 0.7 cm, rounded at the apex with a recurved mucro, cuneate at the base, glabrous

Morphology Reproductive morphology Flowers

Flowers purple-bluish, in terminal or pseudo-terminal simple racemes, few-flowered (up to 12 flowers), (3 -)6- 12 cm long; rachis glabrous; bracts linear-lanceolate, acute, 2 - 2.25 x 0.5 mm, ciliate, caducous; bracteoles linear, 0.5 - 1 mm long, ciliate, caducous; pedicels 2 - 3 mm, sparsely pubescent

Morphology Reproductive morphology Flowers Calyx

Posterior sepal keel-shaped, 3.5 - 4x1- 1.5 mm, ciliate; wing sepals obliquely ovate-elliptic,9-10x3.5-4 mm, acute, 5 – veined from the base, ciliate to glabrescent; anterior sepals keel ­shaped, 3 x 1 mm, ciliate, connate

Morphology Reproductive morphology Flowers Corolla

Upper petals obliquely obovate, 5 - 6 x 4 mm, rounded at the apex; carina 7 - 8 x 4 mm, ciliate at the base; crest 4 - 4.5 mm, fimbriate

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 6, fertile with 2 staminodes

Morphology Reproductive morphology Fruits

Capsule somewhat immature, oblong elliptic in outline 6 - 6.5 x 3 - 3.25 mm, notched, winged, wing 0.15 - 0.4 mm wide

Morphology Reproductive morphology Seeds

Seeds immature, ellipsoid, 4 x 1.25 mm, with white, silky hairs; caruncle asymmetric kidney shaped, ± 1 mm long, hairy, appendages scarcely developed

Distribution

Endemic to Zambia.

Ecology

Kalahari sand in degenerate woodland with many cassava patches.

Conservation

Data Deficient (DD). Little is known about the true distribution of this species. It is here described from only two herbarium collec­tions and locality information is only available for one of them ( Drummond & Cookson 6483). Pope & Pope (1998) place Drummond & Cookson collec­tions from 1959 at the following location: Kalalo 14°57'S 22°40'E. Kalabo is a district in the Western Province of Zambia, less than 100 km from the Angolan border. It is an area near floodplains, covered by Zambezi river waters during the rainy season. North of Kalabo there is a protected area called Liuwa Plains National Park. However, the specimen appears to have been collected outside this protected area. This is one of Zambia'sless populated areas where development pressure is likely to be low. The only possible threat to its native vegetation is the one posed by cattle grazing, a common activity in this area (Timberlake, pers. comm. September 2014). More fieldwork in this region is required to fully understand the distribu­tion of this species and the size of the population, as well as any threats. The lack of data leads to uncertainty in regard to Red List conservation rating. It could plausibly be a restricted range species qualifying under Criterion B or D, but it could equally be possible that the area could support a healthy population under no particular threat that would warrant a Least Concern or Near Threatened category at most. As a result, according to IUCN categories and criteria (2012), this species is assessed as Data Deficient (DD).

Note

There are four species of the section Tetrasepalae which have similar morphologies. However, they all have features which distinguish them. All species are procumbent shrublets or perennial herbs sending up annual shoots, sparsely pubescent to glabrescent in Polygala homblei Exell and P. luteo-viridis Chodat or glabrous in P. poggei and P. kalaboensis. P. kalaboensis and P. homblei are the species with larger flowers, but P. homblei has 8 fertile stamens, narrower leaves and shorter racemes than P. kalaboensis, which has only 6 fertile stamens. P. poggei has smaller flowers and shorter racemes with a pubescent rachis whereas P. kalaboensis has a glabrous rachis. P. luteo-viridis has more flowers per raceme and smaller flowers. P. poggei is the only one of this group which is greenish when dried, similar to P. dewevrei Exell, another species with 6 stamens (subsection Hexandriae), which has subcapitate, lateral racemes, while the racemes of P. poggei are terminal and lateral, not subcapitate. Polygala poggei Gurke, from Angola and Democratic Republic of Congo, is the closest species, but has shorter racemes (up to 6 cm long), with distinctive pubescent rachis and much smaller flowers (wing sepals 6 - 8 x 3 mm).

Type

Zambia, Kalabo, 15 Oct. 1963, Fanshawe 8089 (K, holotype).

Morphology General Habit

Procumbent shrublet or perennial herb, branched, with shoots up to 40 cm long

Morphology Stem

Stems arcuate-ascending, slender, glabrous