Pteronia decurrens Bello, Magee & Boatwr. 2020, sp. nov.
Creators: name: Bello, Anifat O.
name: Boatwright, James S.
name: Bank, Michelle Van Der
name: Magee, Anthony R.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Pteronia
Pteronia decurrens

description: 2. Pteronia decurrens Bello, Magee & Boatwr., sp. nov.
Type:— SOUTH AFRICA, Western Cape Province, Montagu (3320): Wittepoort, Laingsburg (–BB), 23 September 1941, Compton 11851 (holotype NBG!).
Evergreen perennial shrublet ca. 0.3 m in height, much branched; branches erect, glabrous. Leaves decussate, contiguous at base, viscid, simple, linear, 4–10 × 1–2 mm, flattened, coriaceous, tuberculate; apex obtuse; margins entire. Capitula 10- to 12-flowered, homogamous, discoid, apically constricted, decurrent, terminal, solitary, sometimes in clusters of 2 or 3, sessile. Involucre globose, shortly campanulate when opened, 7–10 × 4–7 mm, ca. 8-seriate; involucral bracts glabrous; stereome prominent, slightly fleshy; margins finely ciliate, hyaline; outermost bracts lanceolate, 3–4 mm long; apex acute; middle bracts ovate, 5–6 mm long; apex subacute; innermost bracts oblong-ovate, 7–8 mm long; apex subacute to obtuse. Florets bisexual; corolla yellow, tubular, 7–9 mm long; limb 5-lobed, gradually widening upward; tube pubescent on the middle; anthers 3–4 mm long; apical appendages acute; filament not swollen distally; style branched, 7–8 mm long; branches flattened, ca. 3 mm long, stigmatic-papillate. Pappus of barbellate bristles, biseriate, connate at base, 4–5 mm long, shorter than florets at fruiting stage, straight, straw-coloured. Cypselae ovate, 2–3 × 1–2 mm, dorsiventrally flattened, contracted into a neck at apex, glandular and villous (Figure 3).
Diagnostic characters:— Pteronia decurrens shares the glabrous branches, linear leaves, apically constricted capitula, globose involucre and ovate, glandular-villous cypselae with Pteronia pallens Linnaeus (1782: 357). However, Pteronia decurrens can readily be distinguished by the smooth, unridged branches (fissured and ridged in P. pallens), shorter (4–10 mm long) tuberculate leaves (10–20 mm long and glabrous in P. pallens), decurrent capitula (excurrent in P. pallens) and unfringed bracts with a prominent stereome (prominently fringed and without a prominent stereome in P. pallens).
R.H. Compton collected both Pteronia decurrens and P. pallens at Wittepoort, Laingsburg (Compton 11851 & 11852, NBG) and considered the two collections to represent different species (identifying Compton 11852 as P. pallens but unable to identify Compton 11851).
Distribution and Ecology:— Pteronia decurrens occurs between Laingsburg and Uniondale in the Little Karoo (Figure 2). It favours stony or rocky soil from 250–701 m (a.s.l.). Flowering is from spring to early summer (September– December).
Additional specimens examined:— SOUTH AFRICA. Western Cape: 3320 (Montagu): 14 miles [22.54 km] southeast of Laingsburg (–BB), Acocks 20760 (PRE). 3321 (Ladismith): Goedehoop, 10 km south of Calitzdorp (–DA), 29 September 2006, Bruyns 10536 (BOL). 3323 (Willowmore): Near Uniondale Road Station (–CA), Maguire 784 (NBG).
description: Published as part of Bello, Anifat O., Boatwright, James S., Bank, Michelle Van Der & Magee, Anthony R., 2020, Four new species of Pteronia (Astereae, Asteraceae) from South Africa, pp. 25-32 in Phytotaxa 430 (1) on pages 26-28, DOI: 10.11646/phytotaxa.430.1.4, http://zenodo.org/record/13876949