Schizoglossum austromontanum Bester & Nicholas, 2016

Bester, Stoffel P. & Nicholas, Ashley, 2016, Schizoglossum austromontanum, a novel new species from South Africa (Apocynaceae, Asclepiadoideae, Asclepiadeae), Phytotaxa 273 (1), pp. 43-50 : 44-49

Schizoglossum austromontanum Bester & Nicholas spec. nov. ( Figs. 1 , 2 & 3 ).

Allied to S. singulare Kupicha (1984: 623) in having leaves similar in shape and size; the arrangement of the flowers in the inflorescences and the shape of the pollinia and subapical attachment to the caudicle. It is distinguished from the latter in that S. singulare forms much smaller plants and the corona lobe has double ventral appendages which are totally absent in S. austromontanum . The form of the corona lobes are broadly onion shaped in outline extending from the basal rounded lobe into a drawn out, narrow appendage that is 3- or more-tipped at the apex. Further the corolla is white on the ventral side and basally white becoming pink on the dorsal side of the petals and sub-erect (opposed to S. singulare where it is spreading and livid with red veins on either side).

Type :— SOUTH AFRICA. Maclear District, Bastervoetpad (3127 BB), 31°10’02”S 27°59’38”E, 5 December 2006, S. P. Bester 7446 (holotype, PRE!; isotypes, GRA!, NH!) .

Tubers not seen, neck to 46 mm long. Stems 150–240 mm tall, 2.6–3.5 mm diam., simple, erect, sometimes 1–3- branched from the base; long white hirsute to hispid hairs, denser towards the apex and at nodes. Leaves opposite and decussate, lamina 14.2–46.7 × 5.0– 21.8 mm, oblong-deltoid, base truncate or sagittate and rarely attenuate (usually only in very young leaves), apex sub-acute to round, margins revolute, long white hirsute to hispid hairs, denser below and on veins, above sparser mainly, concentrated along the margins, petiole 2.54–10.80 mm long. Inflorescences: umbels crowded in the upper leaf axils, 3–8-flowered; peduncle 14.7–15.4 mm long, long white hirsute to hispid hairs; bracts linear, 3.1–7.1(–9.0) mm long, dark maroon almost black, with long white hirsute to hispid hairs. Flowers 5-merous, 8.6–9.4 × 12.2–16.8 mm; pedicels 5.5–11.9 mm long, long white hirsute to hispid hairs. Calyx: sepals 2.0–5.5 × 1.4–2.1 mm, lanceolate to narrowly lanceolate, apex acute, ventrally glabrous; dorsally with hirsute to hispid hairs 0.7–0.9 mm long. Corolla lobes free almost to the base, sub-erect, broadly ovate to oblong, flat, apical margin round with a notch, 6.3–11.9 × 3.5–4.9 mm, glabrous except for 0.2–0.3 mm long hairs along the margin; few small hairs on the margins; white inside and white and maroon outside, cream and purple, white with tips maroonish outside, white with purple-maroon veins inside and outside and tips totally purple, or cream outside and inside but with a pink-maroon tipped inside with brown-cream hyaline margin and longitudinal purple-maroon striations of varying degree; buds variable in colour, purple with white. Staminal corona lobes 4.0–5.2 × 1.7–2.6 mm, extended 1.1–1.6 mm outward from the gynostegial column, fleshy, the basal part ovate in outline and ± as high as the process extending over the style-stigma-head, the process sometimes dilated to 0.5–0.6 mm broad apex or expand again into a 1.0–1.1 broad apex, apical teeth on process 0.2–0.9 mm long, process ventrally grooved ending in a shallow sinus on the apical and ventral side of the basal lobe, white with greenish tinge or wholly white, very fleshy, base round in outline, elongating into an apical process ± as long as base, process furrowed on ventral surface, apex of process with 3–5-fimbriated apex. Androecium: anthers rectangular, 1.4–2.1 × 0.6–1.0 mm; anther appendages 0.18–0.24 mm broad margin on apex of anthers, ±rectangular to ovate, white, inflexed over the rim of the gynostegial head covering it almost halfway (to 0.53 mm on its surface); anther wings 0.9 × 0.3 mm, rounded without distinct notch, extending 0.17–0.27 mm from gynostegial column. Pollinarium: pendulous; pollinium 0.52–0.59 × 0.27–0.33 × 0.15–0.18 mm, ovoid to oblong, 0.14–0.17 mm thick, distinctly flanged at the outside in 37–73 μm broad zone; caudicle 160–220 × 40–70 μm, circular to flat in cross-section, pollinium attachment subterminal; corpusculum 0.2–0.4 × 0.1–0.2 mm, ovoid, apex rounded, basally or sub-basally attached to caudicle. Gynoecium: gynostegial fissure 0.5–0.6 mm long, notch at the base; gynostegium 5.6–6.1 × 4.8–5.2 mm, the style-stigma-head 2.3–4.8 mm diam., white. Fruit and seed not known.

Etymology:—the specific name is given for the geographical distribution of the species in the southern Drakensberg (of the Eastern Cape) in opposition to Schizoglossum montanum R.A. Dyer (in Anderson et al. 1961: 104) which is found in the northern KwaZulu-Natal Drakensberg.

Conservation assessment:—This taxon is presently known from a single population occurring in ca. 2.9 × 1 km area on the escarpment of the Bastervoetpad between Ugie and Barkly Pass. In general the label information indicates that the species is locally rare with only a few individuals found. Specific population studies have not yet been carried out to quantify the population size, but currently it is only known from one population with less than 100 individuals. Label information on specimens indicate that in most cases the plants are exposed to frequent fire at the end of winter (August-September) and the vegetation is heavily grazed. It is unknown if numbers are declining and this needs to be monitored. The habitat is intact and only influenced by grazing of cattle and sheep. Over-grazing and trampling by these animals can easily lead to erosion of the humic to clay soils. There is potential for it to occur in many more areas of this unexplored and inaccessible mountainous region. Due to these reasons, despite its single known, extremely restricted population, it is assessed as Least Concern (LC) according to the IUCN (2001) criteria and Rare following Victor & Keith (2004). (Assessors: S.P. Bester & J.E. Victor 17/02/2016).

Summary of criteria met:

• 1 location, no indication that there is a decline in the population, much suitable habitat still unexplored

• EOO = 1.52 km 2

• Assessment: LC, Rare

Distribution and habitat:— Schizoglossum austromontanum is very restricted in distribution and has only been collected on the high-mountainous slopes of the Bastervoetpad in the southern Drakensberg’s escarpment between Ugie and Elliot in the Eastern Cape ( Fig. 4 ). It has been found at altitudes ranging between 1840–2100 m above sea level. It grows on grassy slopes and amongst scrub vegetation of Leucosidea sericea Ecklon & Zeyher (1836: 265) forest precursor patches. The habitat is in sub-Alpine grassland and falls within the Drakensberg Alpine Center of endemism ( Van Wyk & Smith 2001). The geology is Drakensberg basalt which weathers into well-drained humic to turf soils. Plants have always been found in a position of full sun on moderate to steep slopes and an east-south-east to south-east aspect.

Notes: —In herbaria, specimens that are conspecific to this taxon have variously been identified as S. hamatum E. Meyer (1837: 220) and S. stenoglossum Schlechter (1894: 25) . subsp. flavum (N.E. Brown 1909: 419) Kupicha (1984: 623) . The mis-identification as S. hamatum is probably due to gross morphological similarity as dissection would have revealed the totally different shape of the internal floral structures, especially in the corona lobe which is s-shaped in side view and bifidly split for almost its entire length. In S. stenoglossum the width of the corona lobes varies greatly and the base is deltate in shape and may or may not be laterally revolute. S. austromantanum can, however, readily be distinguished from these and any other Schizoglossum species in having a corona lobe that is broadly spoon-shaped and rounded at the base, and then extends into a process without any shoulders and that may be variously split at its tip.

Specimens examined:— SOUTH AFRICA. Eastern Cape. Lady Frere (3127): Maclear district, Bastervoetpad , Mt. Enterprise farm, NW portion of farm, ± 24.5 km W of Ugie —turnoff from Bastervoetpad (– BB), 31.162°S 27.987°E, 2 010 m, 17 November 1993, S. P. Bester 1674 ( NH!; PRU!) ; Maclear district, Bastervoetpad, Mt. Enterprise farm, ± 23 km WNW from Ugie (– BB), 31.160°S 27.988°E, 2 100 m, 17 November 1993, S. P. Bester 1694 ( PRU!) ; Maclear District, Bastervoetpad, Mt. Enterprise farm, ± 25 km WNW from Ugie (– BB), 31.167°S 27.988°E, 1 920 m, 15 December 1993, S. P. Bester 2025 ( PRU!), 2028 ( NU!, PRE!, PRU!) ; Bastervoetpad, Mt. Enterprise farm, ± 26 km W from Ugie (– BB), 1 840 m, 29 December 1994, S. P. Bester 3400 ( PRU!) ; Top of Bastervoetpad ± 30 km W from Ugie on the Wildebeestsriver road (– BB), 31.175°S 27.988°E, 8 December 1995, S. P. Bester 3704 ( PRU!) ; Maclear District, Bastervoetpad (– BB), 31°10’02”S 27°59’38”E, 1 945 m, 05 December 2006, S. P. Bester 7446 ( PRE!; GRA!; NH!) ; Mt. Enterprise 296 farm, ± 20.6 km NE of Elliot (– BB), 31°11’02”S 27°58’30”E, 2 214 m, 7 January 2012, L. E. Makwarela 58 ( PRE!) .

Figures

FIGURE 1. Schizoglossum austromontanum. A, B, flowers (Makwarela 58). C, E, flowers in close-up; D, plant in habit (Bester 7446). F, habitat: Bastervoetpad, Eastern Cape Province. Scale bars:A, C, E, 10 mm; B, D, 20 mm. Photos: S.P. Bester.

FIGURE 2. Scan of holotype of Schizoglossum austromontanum (S.P. Bester 7446, PRE).

FIGURE 3. Schizoglossum austromontanum. A, aerial part of flowering stem. B, leaf, ventral view. C, neck-section between base of the stem and attachment to tuber with adventitious nodes at top of the neck. D, full flower in side view. E, full flower in face view. F, side view of flower with petals and front calyx lobes removed showing corona, anthers and gynostegial column. G–J, corona lobes: G, tip of another lobe; H, side view; I, ventral view; J, dorsal view. K, pollinarium. Scale bars: A, B, C, 10 mm (between A & B); D, E, 2 mm (at D); F, 1 mm; G–J, 0.5 mm (between H & I); K, 0.2 mm. Voucher: S.P. Bester 7446 (GRA!; NH!; PRE!). Artist: G.S. Condy.

FIGURE 4. Map of known distribution of Schizoglossum austromontanum (z). South Africa is shaded in gray. Map created in ArcGIS 10.1.