Acanthopsis villosa H.M.Steyn, 2015

Steyn, Hester M. & Van Wyk, Abraham E., 2015, Taxonomic notes on the Acanthopsis disperma-hoffmannseggiana complex (Acanthaceae, tribe Acantheae), with an interim key to members of the genus, Phytotaxa 219 (1), pp. 1-26 : 14-16

4. Acanthopsis villosa H.M.Steyn , sp. nov. ( Fig. 1 , 3D , 7 )

Acanthopsis villosa is easily distinguished from A. disperma in being a small, perennial subshrub (vs. an acaulescent herb) and from A. hoffmannseggiana in having inflorescences 9–12 mm in diameter (vs. (12–)15–18(–20) mm in diameter) and a densely villose indumentum on the leaves (vs. leaves with strigose to spreading indumentum, never densely villose).

Type: — SOUTH AFRICA. Northern Cape: Namaqualand District . Boesmanplaat, along a turn-off to the west of the road between Gamoep and Platbakkies, 908 m, (3018 AB), 16 August 2013, Koekemoer 4398 (holotype PRE0863486 -0!; isotype NBG!) .

Acanthus carduifolius Th. ss spica villosa E.Mey. , ms. [name written on specimen] sensu Drège 2433 ( P)

Perennial, compact subshrub, up to 70(–100) mm tall with reduced branching and very short internodes (<5 mm long). Leaves oblanceolate, 40–60(–70) × (5–) 7–10 mm; margin strongly undulate, dentate spinose to coarsely dentate spinose, spines fine to strong, 2–4 mm long, yellow; densely villose with long spreading hairs and short, spreading glandular hairs; base attenuate; subsessile or with petiole 2–5(–10) mm long. Inflorescences often attenuate to cuneate with a number of small, ovate to obovate sterile bracts at the base; 25–50(–70) mm long and 9–12 mm in diameter; basal portion of bracts overlapping, rarely exposing parts of the inflorescence axis. Bracts hemispherical to wedge-shaped, 20–22 mm long, base 7–9 mm long; middle and upper bracts ending in 5 primary spines; central primary spine usually compound, with (1)2 or often 3 pairs of marginal secondary spines; 2 lateral primary spines usually with 1 long secondary spine (marginal or basal) directed towards central primary spine and 1(–3) much shorter additional marginal secondary spine(s); secondary spines usually shorter, occasionally equal to primary spines; spines spreading in flower and slightly recurved in fruit; bract base densely villose with long, spreading to atrorse hairs as well as short, deflexed hairs and short glandular hairs; spines glabrescent to villose with short spreading hairs as well as isolated short glandular hairs. Bracteoles linear, 8–9 mm long; densely silky hairy. Calyx with dorsal sepal ovate, cuspidate, 13–14 mm long, densely silky hairy; ventral sepal ovate, 10–11 mm long; densely silky hairy; lateral sepals 8 mm long, densely silky hairy. Flowers purple with cream to white throat, 24–26 × 10–12 mm, tube 7–10 mm long; central lobe usually broader than long, constricted at base, emarginate. Stamens with orangy-brown anthers, 2 mm long; filaments 5–6 mm long, glandular with spreading hairs towards the base. Style with patch of glandular hairs at the base. Capsules ovate in face view, flattened, glabrous, shiny, 7 × 3 mm; 2-seeded. Seeds not seen.

Etymology: —The epithet refers to the densely villose (long, soft weak hairs) indumentum of the leaves and bracts.

Distribution, ecology and phenology: —Only known from a few localities on the plains or inselbergs in Bushmanland, east of the Kamiesberg range, Northern Cape, South Africa ( Fig. 1 ). This distribution falls in the Namaqualand Hardeveld and Bushmanland Bioregions ( Mucina & Rutherford 2006) in the transitional zone between winter- and summer-rainfall regions (falling predominantly in autumn) in very dry areas with the mean annual precipitation ranging between less than 100–160 mm. It is found in the Succulent Karoo ( Rutherford & Westfall 1994, Low &Rebelo 1996, Mucina & Rutherford 2006)and Nama-Karoo Biomes ( Rutherford & Westfall 1994, Low & Rebelo 1996). According to Mucina & Rutherford (2006) and Desmet (2013) the localities within the Bushmanland Bioregion falls within outliers of Succulent Karoo vegetation (Succulent Karoo Biome) within the prevailing Bushmanland Arid Grassland (Nama-Karoo Biome). Specimens were collected at elevations of 900–1070 m, in well-drained sandy soils derived from granite and quartzite. Flowering time: mainly August to October.

Notes: —Although Drège’s specimen (Drège 2433, in P) was included in the concept of Acanthodium carduifolium (L.f.) Nees in Candolle (1847:278), most herbarium specimens (which are now included in A. villosa ),were misidentified as A. disperma (probably because of the dense inflorescences with bracts ending in a compound central primary spine, but without long, viscid glandular hairs), in contrast to A. hoffmannseggiana which has long, viscid glandular hairs on the bracts.

Conservation status: — Acanthopsis villosa has a restricted distribution (Extent of Occurrence 7458 km ²), but is not threatened, and is therefore assessed as Least Concern ( IUCN 2001) (L. von Staden, pers. comm. 2015).

Additional specimens examined: — SOUTH AFRICA. Northern Cape: Little Bushmanland, Aggeneys, Natken farm. North-facing slope of western portion of Naip se Berg 1 km NW of Natken farm house, 1050 m, 29°21’34”S 18°17’04”E, (2918 AD), 6 October 1999, Desmet 2028 ( NBG!) ; 20 km east of Springbok on road to Pofadder , (2918 CA), April 1970, Hugo 208 ( NBG!) ; Namaqualand District. West of Ratelkraal , (2918 CA), 7 September 1950, Maguire 330 ( NBG!) ; Namaqualand Dist. 25 miles east of Springbok at the farm Areb , (2918 CA), 6 August 1967, Rourke 804 ( NBG!) ; Bushmanland, Vaalputs, NECSA Site , (3018 AB), 2 August 2011, Van Rooyen 2790 ( PRE!, PRU!) ; Little Namaqualand, Alewyn’s Fontein , 950 m, (3018 BD), 22 December 1908, Pearson 3346 ( BOL!) ; Calvinia Div.; Braakfontein farm 33 mi. W [ N?] of Loeriesfontein , (3019 CB), 28 October 1963, Schlieben & Van Breda 9849 ( PRE!). Without precise locality: [Illegible] Kaus [Gebirge bei Goedemanskraal, Rustbank und Kookfontein, fide Drège (1843)], 3500 ft (III B), Drège 2433 ( P!), Marloth ex Meyer 6395 ( PRE!) .

Figures

FIGURE 1. Known distribution of species within the Acanthopsis disperma-hoffmannseggiana complex. A: A. ludoviciana (●) and A. tuba (Δ), B: A. adamanticola (▲), A. disperma (○), A. dispermoides (□), A. hoffmannseggiana (■) and A. villosa (ۗ).

FIGURE 3. Comparison of floral parts in members of the Acanthopsis disperma-hoffmannseggianna species complex (from left to right): bract(s) (abaxial views), bracteoles, calyx (4 sepals) and flower. A. A. tuba. B. A. ludoviciana. C. A. adamanticola. D. A. villosa. E. A. hoffmannseggiana. F. A. disperma. G. A. dispermoides. Note: if two bracts per species are illustrated, the one on the left is from lower down in the same inflorescence. Scale bar = 10 mm. Vouchers:A = Von Staden CNR 9139 (PRE), B = Koekemoer 4370 (PRE), C = Germishuizen 10074 (PRE), D = Koekemoer 4398 (PRE), E = Steyn 1907 (PRE), F = Koekemoer 4187 (PRE), G = Steyn 1912 (PRE).

FIGURE 7. Acanthopsis villosa: morphology. A & B. Habit. C & D. Leaf indumentum. E–G. Bract. H. Calyx. I. Flower (corolla lobes blue-purple; throat white to cream). J. Glandular hairs at base of style. K: Seed. Vouchers: C–J = Koekemoer 4398 (PRE), K = Marloth ex Meyer 6395 (PRE). Photographs: N. Helme (A), M. Koekemoer (B).