Astridia parviflora 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 : 145-146

1 Astridia parviflora Klak sp. nov.

( Fig. 1 )

Type: South Africa, Northern Cape, Kwaganap River, between Port Nolloth and Grootmis (2917 AC), 14 Jul. 2014, 150 m above sea level (hereafter abbreviated as a.s.l.), Klak 2396 ( BOL, holo., barcode: BOL0232478 , K iso.) .

Diagnosis: Differs from all other species of Astridia by its smaller flowers (to 30 mm diam. as opposed to 30-70 mm).

Large, robust, densely branched, stiff, erect succulent shrub to 50 X 50 cm. Stem and branches woody, densely leaved, internodes grey, smooth, 17-19 mm long. Leaves opposite, spreading to inclined, pale glaucous green, trigonous, narrowing towards tips, shortly fused, with upper side flattened, sides inflated, 30-55 mm long, 10 X 9 mm, epidermis velvety from short, hair-like papillae. Flowers solitary, terminal and on side branches to 2 cm long, ± sessile, 25-30 mm diam, bracts thick, leaf-like, 1 cm long, 6.5 mm broad and thick, calyx lobes 6, of ± equal length, 2 slightly succulent, to 4 X 2 mm, 4 with membraneous margins, to 7.5 mm long, petaloid staminodes in 1-2 rows, pale pink, with central darker pink stripe, 0.8-1.1 mm broad, obtuse to lanceolate, filamentous staminodes and stamens collected in center into cone, filamentous staminodes in ± 2 rows, as long as the stamens, curled back at tips, 5 X 1-2 mm, stamens numerous, in ± 6 rows, pink in upper third, outer stamens 5 mm long, inner ones shorter to 2.5 mm long, papillate around middle, pollen yellow, stigmas 6, slender, greenish-yellow, 4.5 X 0.8 mm, smooth, top of ovary flat but with conspicuous raised lobes, nectary a dark green crenulate ring. Capsule grey, 6-locular, ± 10 mm diam., rims 2-5 mm high, lower part shortly obconic, 7 mm deep, covering membranes complete, with conspicuous rod-shaped closing bodies, expanding keels diverging, short, valves only opening into erect position, valve wings absent. Seeds brown, to 1.3 mm long, tuberculate.

3.1.1. Distribution and ecology

The species is known only from the Kwaganap River south-east of Port Nolloth, in the arid winter-rainfall region of northern Namaqualand ( Fig. 2 ). Here it occurs on shallow loamy soils overlaying gneiss with quartz-gravel on the surface, at a low altitude of around 150 m a.s.l. Flowering takes place from July to August ( Fig. 1C ). Astridia parviflora is common in the type locality. Further populations may occur in similar habitats at the Holgat River, between Port Nolloth and Alexander Bay.

3.1.2. Distinguishing features and relationships

Astridia parviflora is a large, robust shrub to 50 cm tall and broad, which stands out prominently among the dwarf succulent shrubs where it occurs. The leaves are finely velvety and the fruits are typical for Astridia , i.e. 6-locular, with rod-shaped closing bodies, no valve wings and short keels. It is one of the few species in the genus with pale pink flowers (also known in A. dulcis L.Bolus and A. velutina Dinter ), whereas most other species have red, yellow, white or occasionally magenta to lilac flowers.

This new species is somewhat similar to Antimima pilosula (L. Bolus) H.E.K. Hartmann and Eberlanzia gravida (L.Bolus) H.E.K.Hartmann , which are also robust shrubs with thick leaves and a velvety epidermis. However, these two differ from it in the broad valve wings of their fruits. Members of Ruschia share several features found in Astridia ( Hartmann, 2017a) and evidence from molecular data places Astridia near to some members of Ruschia ( Klak et al., 2013), albeit with only weak support.

3.1.3. Etymology

The epithet refers to the relatively small flowers of the new species.

3.1.4. Conservation status

We consider that this species is rare. Its habitat requirements are very specific: it has been found only near large patches of quartzgravel close to the sea. Given the isolation and the habitat-specificity of the known population, we recommend that it is Vulnerable and placed on the Red Data List of South African plants.

Figures

Fig. 1. Astridia parviflora. A. Habit.B. Leaves and fruits.C. Flower.D. Side view of closed (left, l) and top view of open fruit (right, r). E. Seeds.

Fig. 2. Distribution of Astridia (circles) and of A. parviflora (triangle).