Acanthopsis glabra (Nees) 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 : 104-109

1. Acanthopsis glabra (Nees) H.M.Steyn , comb. nov. ( Figs. 1 , 3A , & 4 )

Basionym:— Acanthodium glabrum Nees von Esenbeck (1847: 278) . Blepharis carduifolia ( Linnaeus 1782: 294) Anderson (1864: 35) var. glabra (Nees) Anderson (1864: 35) . Acanthopsis carduifolia (L.f.) Schinz (1890: 200) var. glabra (Nees) Schinz (1890: 200) . “ Acanthus glaber ” Meyer in Drège (1843: 67, 161), nom. nud (Art. 38).

Type: — SOUTH AFRICA. Northern Cape: Little Namaqualand, Kamies Bergen. [Am Berg bei Kasparskloof, fide Drège (1843)] 3000– 4000 ft [915–1220 m], [19 August 1830], Drège s.n. (lectotype K 000394342! designated here).

Perennial, acaulescent herb or compact subshrub, up to 25 cm tall with very short internodes. Leaves sessile, petiole-like base with spines 1–3 mm long; lamina oblanceolate, 45–70(–100) × (6–)8–10(–12) mm, often grey to grey-green due to densely packed long, strigose hairs, also with subsessile glands; apex acute, base attenuate, margin undulate, coarsely dentate-spinose, spines fine to rigid, 1–3(–6) mm long, yellow to orange-brown. Inflorescences lax (bract lamina overlap <30%), cylindrical, subsessile with a few infertile bracts at the base, (50–)70–140(–250) mm long, (5–) 7–9 mm in diameter. Bracts oblong to obovate, 18–20(–23) mm long (including spines), lamina 9–11(–14) mm long, base obtuse; hirsute with deflexed to appressed short hairs, also with isolated, subsessile glandular hairs abaxially, silky-hairy adaxially; middle and upper bracts usually truncate, ending in 5 primary spines; central primary spine usually simple, rarely with 1 pair of short marginal secondary spines; lateral primary spines usually simple; spines spreading (usually 90°) in fruit. Bracteoles linear, (6–) 8–9 mm long, pubescent with short, deflexed to spreading hairs and short glandular hairs. Calyx with dorsal sepal ovate, apiculate to acuminate, 13–14 mm long, hirsute to pubescent with short, deflexed to spreading hairs and short glandular hairs abaxially, silky-hairy adaxially, 7–9-veined; ventral sepal ovate, 11–13 mm long, hirsute to pubescent with short, deflexed to spreading hairs and short glandular hairs abaxially, silky-hairy adaxially, 5–7-veined; lateral sepals 7–9 mm long, pubescent with short hairs, also with long, silky hairs along margin. Flowers clearly decussate; corolla cream or lilac with darker veins, cream throat, 27–29 × 9(–10) mm, tube 10 mm long, pubescent especially on outside, central lobe wider than long or equal, constricted at the base, truncate to emarginate. Filaments 7–8 mm long, glandular; anthers orange-brown, 2–3 mm long. Style with basal part densely covered with glandular hairs. Capsules 7 × 3(–4) mm. Seeds 4 × 3 mm.

Etymology: —The specific epithet glabra , meaning “smooth/without hairs”, probably refers to the floral bracts which appear glabrous to the naked eye.

Distribution, ecology and phenology: — Acanthopsis glabra is known from mountain slopes and rocky outcrops on the escarpment from west of Spektakel Pass in the north to just north of Bitterfontein in the south (Northern Cape) ( Fig. 1 ) at elevations between 260 and 1500 m. This range falls within the Namaqualand Hardeveld Bioregion ( Mucina & Rutherford 2006) in the Succulent Karoo Biome ( Rutherford & Westfall 1994, Low & Rebelo 1996, Mucina & Rutherford 2006) with the Kamiesberg localities falling in the Namaqualand Cape Shrubland Bioregion ( Mucina & Rutherford 2006) in the Fynbos Biome ( Low & Rebelo 1996, Mucina & Rutherford 2006). It receives predominantly winter rains with an average of 200–250 mm per year. This species prefers deep sandy soils derived from granitic gneisses. Specimens with flowers were collected at the end of August to December.

Conservation status: —This species is widespread and common. Subpopulations are large, and it persists even in heavily overgrazed communal rangelands in the Kamiesberg. As there are no severe threats to this species, the population is not suspected to be declining and it is categorised as Least Concern according to the IUCN Red List Category and Criteria ( IUCN 2012) (L. von Staden, pers. comm.).

Additional specimens examined: — SOUTH AFRICA. Northern Cape: Namaqualand. Farm Kourootjie 316, 260 m, (2917 CD), 9 October 1986, Le Roux & Lloyd 608 ( NBG) ; Namaqualand District, on Springbok-Soebatsfontein road, Messelpadpas , 851 m, (2917 DD), 12 August 2009, Steyn 1565 ( PRE) ; Namaqualand District, Groot Vlei , (2918 DA), 3 September 1951, Johnson 204 ( NBG) ; Namaqualand ; Kamieskroon ; 7 miles [11 km] N. by W. of Kamieskroon , 2500 ft [760 m], (3017 BB), 25 September 1952, Acocks 16476 ( PRE) ; Namaqualand ; Kamieskroon , (3017 BB), 15 December 1936, Adamson 1422 ( PRE) ; Namaqua National Park. On the cement road between Skilpad and Soebatsfontein, 689 m, (3017 BB), 29 December 2010, Koekemoer 3996 ( PRE) ; Namaqualand District. Namaqua National Park , 100 m S of view point on circular route, 691 m, (3017 BB), 11 August 2011, Steyn 1860 ( PRE) ; Namaqualand District. No Heep road N of Kamieskroon, 765 m, (3017 BB), 2 September 2010, Steyn 1767 ( PRE) ; Kamieskroon. Bloupoort , 750 m, (3017 BB), 10 September 2001, Venter JV 9599(JV-52) ( KMG, PRE) ; Namaqualand. In valley 2 miles [3.2 km] west of Garies , (3017 DD), 7 December 1910, Pillans 5640 ( BOL) ; Namaqualand District. N of Leliefontein, 1043 m, (3018 AA), 4 October 2015, Steyn 2119 ( PRE) ; Khamiesberg. Sandy ground at foot of Beacon hill 2 miles [3.2 km] south east of Leliefontein Mission Station , 5000 ft [1500 m], (3018 AC), 17 January 1911, Pearson 6378 ( BOL) ; Garies ; on track between Buffelsfontein and Doornkraal, 491 m, (3018 CA), 22 August 2009, Steyn 1681B ( PRE). Western Cape: Namaqualand District. Farm Eenkokerboom/ Kwanous , 320 m, (3018 CD), 27 August 2012, Steyn 1893 ( PRE) ; Bushmanland and Upper. Near Nieuwfontein, (3018 DA), 21 December 1908, Pearson 3317 ( BOL). Without precise locality: Drège 2436 ( P), s.n. ( S) .

Notes: — Koekemoer 3996 has villose leaves and antrorse hairs on the bracts but is here included in A. glabra rather than in A. scullyi due to the oblong, truncate bracts ending in five simple primary spines.

“ Acanthus glaber ” was proposed by Meyer in Drège (1843) based on a herbarium specimen in Drège’s herbarium, but it was not validly published because no diagnosis or description was provided. Nees von Esenbeck (1847) firstly validly published the name Acanthodium glabrum for the taxon with citing Acanthus glaber as a synonym. Schinz (1890) treated it as a variety of Acanthopsis carduifolia (L.f.) Schinz (1890: 200) and the authorship of the variety name was incorrectly attributed to “(E.Mey.) Schinz”.The correct author citation of the variety Acanthopsis carduifolia var. glabra is therefore (Nees) Schinz. Simultaneously, Schinz published an additional variety, A. carduifolia var. longearistata Schinz (1890: 200) based on a specimen (Schenck 318) collected at “Aus in Gross-Namaland” [ Namibia]. This specimen (Schenck 318) could not be traced and verified and therefore this name is excluded from the current treatment. In his treatment of the genus for Flora Capensis, Clarke (1901) upheld var. glabra but did not mention var. longearistata . Meyer (1961) sunk A. carduifolia var. longearistata under A. disperma .

Although Anderson (1864), Schinz (1890) and Clarke (1901) treated Acanthopsis glabra as a variety of Acanthopsis carduifolia, Drège (1843) and Nees von Esenbeck (1847) recognised it at species level in Acanthus and Acanthodium respectively. Until more information becomes available, we have decided to follow Drège and Nees in recognizing A. glabra as a distinct species as the latter is probably more closely related to A. scullyi (S.Moore) Obermeyer (1937: 138) than to A. carduifolia .

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 4. Acanthopsis glabra. A & B. Habit. C & D. Leaf indumentum (abaxial). E & F. Bract. G. Calyx. H. Corolla (lobes lilac to cream; throat cream). I. Glandular hairs at base of style. J. Capsule. K. Seed. Vouchers: C–F = Acocks 16476 (PRE), G–I = Steyn 1893 (PRE), J & K = Steyn 2119 (PRE). Photographed by: H.M. Steyn (A, C–K) and M. Koekemoer (B).