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| Petalidium konkiepense Swanepoel & A.E.van Wyk, in Swanepoel & van Wyk. 2023. |
Abstract
Petalidium konkiepense, here described as a new species, is only known from the Gariep Centre of Plant Endemism in
southern Namibia, where it grows on arid hillsides and along drainage lines. Diagnostic morphological characters for
P. konkiepense include the rigid, cylindrical distal stems (quadrangular when young), grey or dark brownish grey bark
(white to cream when young), densely puberulent vegetative parts with widely spaced robust glandular and eglandular
trichomes, and the oblanceolate leaves with prominent midrib and principal lateral veins. A comparison of some of the more
prominent features to differentiate Petalidium konkiepense from its morphologically most similar relatives, P. linifolium and
P. cymbiforme, is provided. Based on IUCN Red List categories and criteria, a conservation assessment of Endangered under
criteria B1 is recommended for the new species.
Keywords: desert, endemism, flora, Gariep Centre, Ruellieae, taxonomy
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| Petalidium konkiepense, habitat and habit. A. Plant in flower (right foreground) with several plants (low greyish dwarf shrubs— one marked with an asterisk—in background), growing among limestone rocks of the Nama Group (Farm Churutabis-Sonntagsbrunn 108, ||Kharas Region, Namibia). B. Mature plant, mainly past flowering, with persistent bracteoles (Farm Soutkuil 181, ||Kharas Region, Namibia). Photographs by W. Swanepoel. |
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| Petalidium konkiepense, morphology of flowers and leaves. A. Branchlet showing narrow leaves and violet flower. B. Flower in front view; mauve variation. C. Flower in side view, with bracteoles; mauve variation. D. Leafy shoot with flower in front view, and with bracteoles; violet variation. E. Leafy shoot with flower in lateral view, and with bracteoles; violet variation. Photographs by W. Swanepoel. |
Petalidium konkiepense Swanepoel & A.E.van Wyk, sp. nov.
Diagnosis:—A woody dwarf shrub up to 1 m tall, morphologically most similar to Petalidium linifolium, differing by having the leaf lamina oblanceolate or rarely a few narrowly lanceolate (sensu Lindley), flat, subconduplicate to conduplicate towards the apex (vs. linear or narrowly lanceolate [sensu Lindley], flat, often recurved towards the apex), pale green or yellow-green and not glossy (vs. pale to bright green and glossy, covered with a glutinous secretion), with midrib and 1–4 principal lateral veins each side (vs. principal lateral veins absent), venation prominent both sides (vs. adaxially only), indumentum puberulent, abaxially often with widely spaced short-stalked glandular and robust long-stalked multi-cellular glandular trichomes in addition (vs. glabrous, except for short conical trichomes adaxially).
Etymology:—The specific epithet refers to the Konkiep River (a tributary of the Fish River) in the Gariep Centre of Plant Endemism in southern Namibia. The name “Konkiep” (also spelled “Koin kieb”, “Konkip”, or “Koanquip”) is derived from the Khoesaan language Khoekhoegowab (Alexander 1838, Sprigade & Moisel 1904, Nienaber & Raper 1983, Raper et al. 2014). Its meaning, however, is uncertain and has most probably been lost in time. It has been claimed by some authorities that “Konkiep” is an adaptation of “Goageb” (also spelled “Goangib”), which is said to mean “the swollen twin river” (Nienaber & Raper 1983, Raper et al. 2014). However, we do not find this explanation convincing as, according to probably the earliest report on the geography of the region by Alexander (1838), Goageb (as “Gnuanuip”), is the name of a tributary of the Konkiep (as “Koanquip”) River.
Wessel Swanepoel and Abraham E. van Wyk. 2023. Petalidium konkiepense (Acanthaceae), A New Species from Namibia. Phytotaxa. 585(1); 29–38. DOI: 10.11646/phytotaxa.585.1.3
