Smicrostigma warmwaterbergense Klak, 2001

Klak, Cornelia, Hanáček, Pavel & Bruyns, Peter V., 2023, Two New Species of Aizoaceae (Ruschieae, Ruschoideae) from the Cape, South Africa., Haseltonia 29 (1), pp. 16-23 : 19-20

1. Smicrostigma warmwaterbergense Klak sp. nov. ( Fig. 3 )

This new species resembles Smicrostigma viride in its habit and the shape of its leaves but differs in that its flowers open and close repeatedly over several days and expose the reproductive parts

fully when open (remaining open with reproductive parts hidden in S. viride ). It differs further in having. 9–13 locules in its capsules (7–10 locules in S. viride ).

Type: SOUTH AFRICA. Western Cape, Montagu (3320): Summit of southern side of Warmwaterberg, towards boundary of ‘Cocktail’, Sanbona (-- DC), ± 1000 m, 9 Dec. 2021, Bruyns 14033 (holotype BOL!, isotype NBG) .

Erect perennial, densely branched shrubs 15–20 × 15–20 cm, branching from the base, branches slightly succulent, becoming woody with age, 3–5 mm diam., smooth, young internodes pale brown, 10–13 × 1.5–2 mm. Leaves opposite, spreading, united at the base and sheathing the branch for 10–13 mm, sheath without a line and becoming woody with age, smooth, free parts 4–5 mm long, trigonous, adaxially flat, inconspicuously keeled, 2–3 mm broad and thick, apiculate. Flowers solitary, sessile, bracteoles not different from the leaves, 25–30 mm diam.; sepals 5, subequal, succulent; petaloid staminodes brilliant magenta, 2- to3-seriate, inner petals shorter and emarginate, outer ones lanceolate, 13 × 1.2 mm, filamentous staminodes in 3–4 rows, white, outer ones pale pink, collected into a cone around the stamens, 5.5–6 × 0.3 mm; stamens numerous, filaments white, without papillae, 2–4 mm long, inner ones shortest, anthers yellow; stigmas 9–13, slender, ± 2.5 mm long, top of ovary slightly raised in center; nectary forming green, crenulated ring. Capsule 9- to 13-locular, covering membranes completely covering locules, 8–9 mm diam., top low, bowl-shaped, base of capsule funnel-shaped, rims low, expanding keels basally parallel and apically spreading, tapering into awns instead of valve wings, closing-bodies absent, no additional closing-device below the covering membranes. Seeds brown, ca. 0.7 mm long, testa cells cushion shaped.

DISTRIBUTION AND ECOLOGY

Smicrostigma warmwaterbergense is apparently rare and it is only known from the type locality from near Montagu on the southern side of the Warmwaterberg ( Fig. 4 ), within the Sanbona Wildlife Reserve. It appears to be restricted to the plateau, at around 1000 m. The species is associated with sandstone soils within fynbos, where it grows in flat rocky areas, among other short shrubby, open vegetation. A population of an estimated 80 to 100 plants was found in flower in an area which had burnt seven years before. The vegetation is classified as Rainshadow Valley Karoo, SKv8 Western Little Karoo ( Mucina et al. 2006). Smicrostigma warmwaterbergense flowers in December.

The distribution of S. warmwaterbergense overlaps with S. viride , which has been recorded between Montagu and Uniondale (Fig. 4). However, in the area where the two species co-occur, S. viride is restricted to lower altitudes on different soils. Smicrostigma viride is typically found in renosterveld, in shaly often stony or gravelly and loamy soils, either in flats or on gentle slopes. Elsewhere, it has been observed in rocky spots within fynbos.

DISTINGUISHING FEATURES AND RELATIONSHIPS

Smicrostigma warmwaterbergense has a similar habit to Smicrostigma viride . The fruits of S. warmwaterbergense only differ in the higher number of locules ( Table 1 ). The major differences lie in their flowers: In S. viride the flowers remain open after anthesis and until they fade, whereas they are open and close each day for several days in S. warmwaterbergense . In addition, in S. viride the staminodes are recurved at the tips and partly conceal the stamens. For this reason, Louisa Bolus had transferred this species to Erepsia , which differs by the possession of a true hypanthium. In contrast, in S. warmwaterbergense the filamentous staminodes are collected first into a cone around the stamens and then later spread as the flower matures.

ETYMOLOGY

The epithet refers to the Warmwaterberg, a mountain-range in the Little Karoo, where the species was discovered.

CONSERVATION STATUS

While botanical surveys in future are likely to uncover additional populations of this species, it nevertheless appears to be rare. Given the isolated nature of the known population, we recommend that it is considered Vulnerable and placed on the Red Data List of South African plants.

Figures

Fig. 3. Smicrostigma warmwaterbergense, Bruyns 14033 (BOL) (A, B, D-F): A. Flowering branch, December 2021, South Africa. B. Close-up of flower with stamens visible. D. Side view of closed capsule. E. Top view onto open capsule. F. Seed. Smicrostigma viride: C. Close-up of flower showing the stamens and stigmas concealed by the staminodes, Klak 3035 (BOL).

Fig. 4. Distribution of Namaquanthus cephalophylloides (circle), N. vanheerdei (triangle), Smicrostigma viride (inverted triangle), S. warmwaterbergense (square).