Acanthopsis glandulopalmata H.M.Steyn, 2017

Steyn, Hester M. & Van Wyk, Abraham E., 2017, Taxonomic notes on Acanthopsis (Acanthaceae, tribe Acantheae): the group with semi-dense spikes and 5 - fid bracts, Phytotaxa 324 (2), pp. 101-121 : 113-115

4. Acanthopsis glandulopalmata H.M.Steyn , sp. nov. ( Figs. 1 , 3D & 7 )

Type: — SOUTH AFRICA. Northern Cape: Namaqualand District. On track between Anenous/Kosies to Umdaus in Wyepoort River Valley, 690 m, (2917 BA), 25 August 2012, Steyn 1890 (holotype PRE 0861467!, isotype NBG 01461963!).

Diagnosis: — Acanthopsis glandulopalmata differs from other species with semi-dense spikes and 5-fid bracts in having bracts with winged primary spines (nearly always simple) with long, glandular hairs (not narrow to narrowly winged primary spines with short, eglandular hairs) and a relatively large corolla of 28–32 mm long (not 20–25(–27) mm long).

Perennial, compact subshrub, 7–10 cm tall with very short internodes. Leaves sessile, base petiole-like with spines 3–7 mm long; lamina oblanceolate, (25–)35–50(–70) × 5–10(–12) mm, strigose with short, white hairs, also with subsessile glandular hairs; apex acute, base attenuate, margin undulate, dentate-spinose, spines rigid, 3–6 mm long, yellow to brown. Inflorescences semi-dense, cylindrical, subsessile, 45–50(–70) mm long, 8–10(–12) mm in diameter. Bracts obovate to broadly obovate, (15–19)– 24 mm long (including spines), lamina 10–11 mm long, base obtuse; lower bracts hirsute with deflexed to spreading short, white hairs, middle to upper bracts hirsute with spreading short, white hairs, together with glandular hairs abaxially, silky-hairy, also with short, white hairs and glandular hairs adaxially; middle and upper bracts ending in 5 primary spines; central primary spine usually to nearly always simple, if compound, then with 1 pair of short marginal spines (prickles); lateral primary spines nearly always simple; spines spreading to recurved in fruit. Bracteoles linear, 7–8(–11) mm long, silky-hairy with some isolated glandular hairs. Calyx with dorsal sepal ovate, acuminate, 13–14(–16) mm long, silky-hairy with some isolated glandular hairs abaxially, silky-hairy adaxially, 7–9-veined; ventral sepal ovate, 12–14 mm long, silky-hairy with some isolated glandular hairs abaxially, silky-hairy adaxially, 5–7-veined; lateral sepals 9 mm long, with some isolated glandular hairs abaxially, silky-hairy adaxially. Corolla lilac to purple with lemon-yellow throat, 28–32 × 10–11 mm, tube 9–10 mm long, central lobe as wide as long, truncate to rounded. Filaments 7–8 mm long, glandular; anthers orange-brown, 3–4 mm long. Style with patch of glandular hairs at the base. Capsules 6–8 × 3–4 mm. Seed 5 × 3–4 mm.

Etymology: —The specific epithet glandulopalmata , meaning “glandular-palmate”, refers to the hand-shaped bracts, covered in glandular hairs.

Distribution, ecology and phenology:— Acanthopsis glandulopalmata is endemic to the Northern Cape and is known from three localities in an area to the north-west of Steinkopf with one outlier population north-west of Springbok ( Fig. 1 ). It is centred in the core part of the Gariep Centre of Endemism ( Van Wyk & Smith 2001). This distribution falls within the Succulent Karoo Biome ( Rutherford & Westfall 1994, Low & Rebelo 1996, Mucina & Rutherford 2006) in the Richtersveld Bioregion: Umdaus Mountain Succulent Shrubland, Anenous Plateau Shrubland and Lekkersing Succulent Shrubland ( Mucina & Rutherford 2006) where it receives predominantly winter rains with an average of 100–200 mm per year. The specimens were collected on plains with quartzite pebbles in well-drained, sandy soils at elevations between 670– 700 m. Desmet & Ellis 656 was collected at 120 m in the Namaqualand Hardeveld Bioregion where it receives <100 mm of rain per annum, but probably more frequent fog that the inland populations. Specimens with flowers were collected between August and October.

Conservation status: — Acanthopsis glandulopalmata is known from four widely scattered subpopulations (EOO 1954 km ²). The threats affecting this species, particularly overgrazing, is likely to affect most areas with suitable habitat, and therefore it is threatened across its range. The population is likely to be declining at all known locations. It is therefore assessed as Endangered based on precautionary principles (Endangered B1ab(iii)) according to the IUCN Red List Category and Criteria ( IUCN 2012) (L. von Staden, pers. comm.), but may need to be downlisted in future if further field surveys indicate that there are more than four subpopulations. Further field surveys are needed to gain a better understanding of the population structure and abundance of this species.

Additional specimens examined (Paratypes): — SOUTH AFRICA. Northern Cape: Tussen Ploegberg en Stinkfonteinberge , 550 m, (2817 CA), 15 September 1985, Zietsman & Zietsman 773 ( NMB, PRE, PRU) ; Namaqualand ; ± 16 mi. NW of Steinkopf ( Hangbal River ), 2200 ft [670 m], (2917 BA), 8 October 1956, Leistner 797 ( PRE) ; Namaqualand District. On track between Anenous / Kosies to Umdaus in Wyepoort River Valley , 697 m, (2917 BA), 25 August 2012, Steyn 1889 ( PRE) ; Namaqualand District. Wyepoort River Valley , 695, (2917 BA), 9 October 2015, Steyn 2125 ( PRE) ; Nuttabooi Kleinzee, Nuttabooi mining area approximately 40 km from Kleinzee on the Springbok road, south bank of Buffels , 120 m, (2917 CB), 21 June 1997, Desmet & Ellis 956 ( NBG) .

Desmet & Ellis 956 has greyish leaves covered with densely packed appressed hairs. It was collected at a much lower elevation and in a different bioregion than the rest of the specimens, and is here included in A. glandulopalmata based on the semi-dense inflorescences with palmate bracts. However, the inflorescence is very narrow and no glandular hairs are visible on the bracts, as the inflorescences are old (probably from the previous season).

Figures

FIGURE 1. Known distribution of A. glabra (○), A. scullyi (▲), A. nitida (□), A. glandulopalmata (■) A. insueta (Δ) and A. carduifolia (●). Thunberg’s route (1774) indicated in red. (for explanation see Notes under taxonomic treatment of A. carduifolia)

FIGURE 3. Comparison of floral parts, associated bracts and bracteoles (from left to right): bracts (2), bracteoles (2), calyx (4 sepals: dorsal, ventral and 2 lateral ones) and corolla with anthers.A. A. glabra, B. A. scullyi, C. A. nitida, D. A. glandulopalmata, E. A. insueta, F. A. carduifolia. Note: the bract on the left is from lower down in the same inflorescence. Scale bar = 10 mm. Vouchers:A = Steyn 1893 (PRE), B = Steyn 1911 (PRE), C = Steyn 1884 (PRE), D = Steyn 1890 (PRE), E = Steyn 1805 (PRE), F = Koekemoer 4620 (PRE).

FIGURE 7. Acanthopsis glandulopalmata. A & B. Habit. C & D. Leaf indumentum (abaxial). E &F. Bract. G. Calyx. H. Corolla (lobes lilac to purple; throat lemon-yellow). I. Glandular hairs at base of style. J. Capsule with seed. K. Seed. Vouchers: C–I = Steyn 2125 (PRE), J & K = Steyn 1889 (PRE). Photographed by: M. Koekemoer (A) and H.M. Steyn (B–K).