Ruschia variabilis Klak, 2023

Klak, Cornelia, Hanáček, Pavel & Bruyns, Peter V., 2023, Six new species of Ruschieae (Aizoaceae) and further notes in Ruschia, South African Journal of Botany 156, pp. 144-161 : 146-147

1 Ruschia variabilis Klak sp. nov.

( Fig. 3 )

Type: South Africa, Northern Cape, between Port Nolloth and Grootmis (2917 AC), 19 Jul. 2021, 150 m a.s.l., Klak 2919 ( BOL, holo., barcode: BOL0232477 ) .

Diagnosis: Differs from species of subg. Tumidula by its 5- to 8-locular fruits; from subg. Cymbifolia by the fusion of its leaves into a sheath; from Stayneria by its smaller flowers (to 25 mm diam. as opposed to ± 40 mm in Stayneria ); from Astridia by its 5- to 8-locular fruits and flowers in cymes of 1-3 (as opposed to strictly 6-locular fruits and solitary flowers in Astridia ).

Sturdy, chunky erect succulent shrub to 30 X 20 cm, with woody stem and branches. Leaves opposite, glaucous, spreading, trigonous,

fused into a sheath 15-20 mm long, with a line where the leaves are fused, tips pointed, free parts 37-55 mm long, 8-10 mm broad and thick, epidermis smooth. Flowers in cymes of 1-3, 20-25 mm diam., pale pink to almost white, pedicels to 2 mm long, calyx lobes 6-7, 2 more succulent than the others, ± 10 X 5 mm, with membranous flap along the edge, bracts leaflike, thick and succulent, to 19 X ± 7 mm wide and thick; petaloid staminodes in 2 rows, 8-10 X 0.7-0.9 mm, lanceolate to obtuse, filamentous staminodes fused with stamens at bases, 4.5-6.0 X 0.2 mm, in 2-3 rows, with hair-like papillae in lower half, collected into cone around stamens; stamens numerous, filaments white, 2.5-5.0 mm long, inner ones shortest, white, with hair-like papillae around the middle, in 3-4 rows, pollen yellow; stigmas 5-8, greenish yellow, pointed, 2-3.5 X 0.5 mm, feathery, broadest at middle, top of ovary slightly raised in the center, but without any lobes; nectary in a green, crenulated ring. Capsule (5-) 6- (to 8-) locular on the same plant, c. 9 mm diam., top raised to 3 mm, with low rims, lower part 4-5 mm deep, short funnel shaped, keels touching at base and then diverging, covering membranes firm and with additional conspicuous closing ledge below, closing bodies rod-shaped, valve wings absent. Seeds dark brown, 1.2-1.3 X ± 1 mm, D- shaped, almost smooth.

3.1.5. Distribution and ecology

Ruschia variabilis is known only from the Kleinzee area, between Grootmis and 20 km north of Kleinzee, in the arid winter-rainfall region of northern Namaqualand ( Fig. 4 ). Here it occurs in stony, gravelly soil or on quartzitic gneiss or schist slopes, at low altitudes from 10 -170 m a.s.l., within a few kilometres of the sea. Plants were found in flower from July to August, with their main flowering-time in July.

3.1.6. Distinguishing features and relationships

Ruschia variabilis forms erect, chunky shrubs, with (5-) 6- (to 8-) locular fruits on the same plant. Its chunky appearance is suggestive of species of Astridia , all of which differ by having solitary flowers and strictly 6-locular fruits. The smooth leaves which are fused into a

short sheath and the ternate, moderately sized (to 25 mm diam.) flowers place this species into subg. Tumidula (where solitary flowers are only known in Ruschia lineolata (Haw.) Schwantes ). Since members of this subgenus are characterized by 5-locular fruits, with small closing bodies and no valve wings, the frequently higher number of locules in R. variabilis distinguishes this species from the others. Stayneria , a monotypic genus endemic to the Worcester-Robertson area in the Western Cape, is closely allied to members of subg. Tumidula ( Klak et al., 2013) and differs by having 5- to 8- locular fruits which, once they have opened, do not close completely again.

3.1.7. Etymology

The epithet refers to the variable number of locules typical for this species.

3.1.8. Conservation status

Plants were found in a restricted area ( Fig. 4 ) on low hills close to the sea, which are characterized by a cooler climate than areas further inland and away from the sea. In addition, the substrate where it occurs differs from the sandy coastal habitat surrounding these low hills. As we consider the habitat preference of this species to be rather specific, we suggest a status of vulnerable (VU) for this species.

3.1.9. Additional specimens investigated

South Africa. NORTERN CAPE: 2917 (Springbok): Kleinzee (-CA), 10 m a.s.l., 10 Jul. 1998, Klak 483 ( BOL) ; Grootmis (-CA), steep quartzitic slope, 30 m a.s.l., 8 Aug. 2017, Van Munster 23 ( BOL) ; Grootmis (-CA), in a mix of crumbling gneiss and schist, 16 m a.s.l., 18 Jul. 2021, Klak 2911 ( BOL) .

Figures

Fig. 3. Ruschia variabilis. A. Habit.B. Leaves and flowers. C. Side view of closed (l) and top view of open fruit (r). D. Seeds.

Fig. 4. Distribution of new species of Ruschia: R.variabilis (circle), R.pseudocrassa (triangle), R.rupestris (inverted triangle).