Drosanthemopsis kwaganapensis Klak, 2018

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 (10), pp. 67-81 : 78-79

3. Drosanthemopsis kwaganapensis Klak , sp. nov.

Type: South Africa, Northern Cape, Kwaganap River, between Port Nolloth and Grootmis (2917 AC), 14 Jul. 2014, 150 m, Klak 2379 ( BOL, holo.; NBG, iso.) .

Erect, densely branched succulent perennial shrublet 150 (−200) mm tall, to 200 mm diam., young internodes brown, stems woody, distinction between long shoots and short shoots small, long internodes to 15 mm long, young internodes indistinctly papillate becoming smooth with age. Leaves dirty green, only slightly reddish suffused, boat-shaped, spreading, top flat, keels indistinct, leaf-pairs isophyllous, basally connate for c. 1/3 of their length; sheeth 5–8 mm long, free parts 9–11 mm long, 5–7 mm broad and thick; epidermis with large bladder cells with thickened outer walls, cells 0.075–0.1 mm, ±circular to polygonal, bladder cells with flat top covered with many antler-like protrusions, especially along the margin of the top. Flowers solitary, terminal, petaloid staminodes white, filamentous staminodes absent or very few, filaments white, 30–35 mm diam., pedicels c. 5 mm long; sepals number unknown, succulent; flowering time August to September. Fruit a hygrochastic capsule, old capsules gray, capsule as seen from above ±circular, 5–8 mm diam., top almost flat, rims very low, lower part funnel-shaped; locules 7 or 8; borderline between expanding keels and expanding sheet distinct, keels broad and only slightly diverging; covering membranes thin, and without any additional closing devices, covering ¾ of the locule, closing body absent, valve wings broad. Seeds ochre, almost smooth, c. 0.7 × 0.5 mm.

Distribution and ecology: The species is known from the Kwaganap River south-east of Port Nolloth and from Grootmis, in the arid winter-rainfall region of northern Namaqualand ( Fig. 6 ). Here it occurs on shallow loamy soils overlaying gneiss with quartz-gravel on the surface.

Diagnostic characters: In D.kwaganapensis and D. vaginata the antler-like protrusions on the epidermal surface are particularly prominent and they are branched ( Fig. 5A & B ), whereas they are mostly unbranched and shorter in the other two species of Drosanthemopsis ( Fig. 5C & D ). Drosanthemopsis kwaganapensis is the only species with an erect, densely branched habit, combined with thick, dirty green, succulent leaves.

Etymology

The epithet “ kwaganapensis ” refers to the type locality at the Kwaganap River in Namaqualand.

Conservation status: The species is known from two quartz patches between Port Nolloth and Grootmis. At both localities about 20 plants were seen. We propose an IUCN category of vulnerable (VU) in line with that for D. vaginata .

Additional specimens examined

South Africa. NORTHERN CAPE: 2917 (Springbok): Grootmis , (-CA), in saline loam with overlaying quartz-gravel at base of schist cliffs, 20 m, Klak 2573 ( BOL, NBG) .

Note: Drosanthemum kwaganapensis may be identical with the northern coastal populations of Jacobsenia vaginata mentioned by Ihlenfeldt (1997: 111, Map 1), but for which no collections were cited. A living collection, Hammer & Jürgens s.n. from the Kwaganap River, which was obtained from S. Hammer, is conspecific with this newly described species and formed the basis for its re-collection and investigation.

Figures

Fig. 6. Distribution of Drosanthemopsis and Knersia, with phytochoria indicated (Knersvlakte,Riethuis-Wallekraal, Southern Richtersveld).

Fig. 5. Scanning electron micrographs of the leaf epidermis found in the Drosanthemopsis clade.A. D.kwaganapensis, Klak 2379 (BOL),showing the conspicuous antler-like protrusions; B. D.vaginata, Klak 2311 (BOL),with antler-like protrusions similar to those found in D.kwaganapensis; C. D.bella, Klak 2309 (BOL),with fewer and smaller antler-like protrusions than found in A&B.D. D. diversifolia, Klak 883 (=Knersia diversifolia) (BOL).