Crassothonna moniliformis R.J.McKenzie & A.P.Dold

Mckenzie, Robert J. & Dold, Anthony P., 2024, Crassothonna moniliformis (Asteraceae, Senecioneae), a new species from the Albany Centre of floristic endemism, South Africa, Phytotaxa 641 (4), pp. 243-254 : 248-252

Crassothonna moniliformis R.J.McKenzie & A.P.Dold , sp. nov. ( Figs. 2 , 3A & 4 )

Type: — SOUTH AFRICA. Eastern Cape: Kidd’s Beach [3327BA], Dyam-Dyam Village , Kiwane , between village and coast along Kiwane River , 6 January 2022, A.P. Dold 16064 (holotype: GRA!) .

Diagnosis: —Prostrate perennial herb distinguished from Crassothonna capensis in having slender, weak, trailing, precociously adventitiously rooting stems, distantly branched and forming diffuse patches, with erect, globose-obovoid to obovoid to subclavate, rounded to obtuse, conspicuously mucronate leaves, capitula solitary or in a ±corymbiform compound synflorescence of 2–4 capitula, 7–9 ray florets per capitulum, and functionally staminate peripheral disc florets.

Herb perennial, prostrate, forming widely spreading, diffuse patches to at least ± 50 cm diam., to ± 10–15 cm tall in flower. Roots fibrous, nodal adventitious roots forming precociously on spreading stems and from woody stems. Stems terete, spreading stems distantly branched, 1.5–3.0 mm diam., glabrous, red-purple, internodes 3–10(–20) mm long; older stems woody, leafless, 3–5 mm diam. Leaves alternate, spirally arranged, ±evenly distributed along stem, base often twisted so that the leaf orientation is erect, 10–25 mm long × 5–9 mm wide, subclavate to obovoid to globose-obovoid, usually terete, sometimes slightly flattened and grooved adaxially, carnose, pale green or olivegreen to partially to entirely red-purple, at least young leaves slightly glaucous, apex obtuse to rounded, mucronate, mucro red-purple, acute, 0.5–0.6 mm long, lamina gradually tapering to base or base conspicuously narrowed, sessile, pseudopetiole absent, base width 2.0– 2.5 mm, partially amplexicaul, dense tuft of short woolly hairs on leaf base in axil. Inflorescence terminal, simple or ±corymbiform, dichotomously branched, stem to ± 75 mm long, red-purple, slightly glaucous, glabrous, succulent; bract at each fork lanceolate-linear, not terete, 1.5–3 mm long × 0.4–0.8 mm diam. at base, tuft of dense white woolly hairs in axil. Peduncle ascending to erect, 10–50 mm long × 0.5–1.0 mm diam., red-purple, slightly glaucous, glabrous, scale-like bracts absent. Capitulum solitary or 2–4 per synflorescence, 15–20 mm diam. (with ray floret limbs fully unfurled), radiate, heterogamous. Involucre ±cupuliform, diurnally campanulate during anthesis, tapering at base, ecalyculate, 4.8–6.3 mm long × 3.3–4.5 mm diam., involucral bracts uniseriate, 8, basally connate at most for ca. 0.5 mm, elliptic-deltoid to lanceolate-elliptic to lanceolate, 4.5–5.5 mm long × 0.9–2.8 mm wide, red-purple, slightly glaucous, margins membranous (3 bracts) or membranous on one side only (2 bracts) or non-membranous (3 bracts), obtuse to acute, apex with dense tuft of minute ciliate hairs to ca. 0.2 mm long, diurnally strongly reflexed to partially coiled during anthesis. Receptacle somewhat convex, to 0.8 mm high, minutely alveolate, alveoles to ca. 0.2 mm high. Ray florets 7–9, radiate, functionally pistillate; Corolla yellow, tube funnelform, 1.5–1.8 mm long × 0.4–0.5 mm diam., glabrous, adaxial lobes absent, limb ovate-oblong, 10–11 mm long × 1.8–2.5 mm diam., fully extended diurnally and recoiled overnight during anthesis, veins green abaxially, apex obtuse-truncate, minutely denticulate, teeth 2; Style 1.7–2.2 mm long, bifid, branches 0.8–1.1 mm long, obtuse, flattened, adaxial surface of each branch with two longitudinal stigmatic bands, each minutely papillate, apex with group of larger rounded cells but sweeping hairs absent; Ovary obovoid-terete, 0.6–0.8 mm long × 0.4–0.5 mm diam.; Cypsela obovoid-obconical, weakly tangentially flattened, not angular, tapering gradually to base, 2.5–2.8 mm long × 1 mm diam. (radial) × 1.2 mm diam. (tangential), covered with uniformly dense, silvery-white, appressed myxogenic twin hairs, apex rounded; Pappus setose, bristles ∞, erect, straight, 2.8–3.5 mm long, white, caducous, attached to thickened apical rim on ovary/cypsela, apex predominantly non-forked, occasionally minutely forked, apical cells acute, margin with minute teeth for most of length, teeth mostly ascending, acute, strongly reduced or absent in basal portion. Disc florets ca. 25–40, functionally staminate; Corolla yellow, narrowly funnelform, tube 0.8–1.0 mm long × 0.2–0.3 mm diam., glabrous, terete, limb narrowly campanulate, 1.5–2.2 mm long × 0.4–0.7 mm diam., lobes 5, deltoid, 0.5 mm long, abaxial surface with dense short glandular hairs ca. 0.1 mm long; Stamens anther 1.8–2.0 mm long (including apical appendage), apical appendage 0.3 mm long, ovate, obtuse, endothecial wall thickenings radial, base ecalcarate, ecaudate, obtuse, filament collar balusterform; Style simple, unbranched, apex conical, cone 0.2–0.3 mm long with short obtuse-rounded sweeping hairs, subtended by whorl of longer acute-obtuse sweeping hairs; Ovary terete, glabrous, peripheral florets 1.0– 1.5 mm long × 0.2–0.4 mm wide, central florets 2.0– 2.5 mm long × 0.2–0.3 mm wide; Pappus bristles of peripheral florets as for ray florets, of central florets ca. 13–20, 1.7–2.4 mm long, persistent, otherwise as for ray florets.

Phenology: —Flowering in its natural habitat is recorded in January, April–May and August–October, and therefore may occur year-round or be rainfall-dependent.

Distribution and habitat: — Crassothonna moniliformis is known only from one restricted area, extending from Mount Pleasant inland of Kayser’s Beach to the Kiwane River, southwest of East London in the Eastern Cape province ( Fig. 4 ). Rowley’s (1994) photographs of the species growing at “Kayser’s Beach” were possibly taken at the Mount Pleasant subpopulation. The plants grow in shallow sandy sediments overlying exposed calcareous sandstone pavements of the Nanaga Formation of the Algoa Group ( Le Roux 1989). The pavements are located on sandy dunes stabilised by coastal thicket on gentle north-facing slopes at ca. 30–100 m above sea level. The pavements host a rich suite of dwarf succulent and geophytic plant taxa, including a number of localised taxa endemic to the Albany Centre of floristic endemism ( Dold & Brink 2004). The region has a temperate climate with mean annual precipitation of ca. 500 mm, year-round rainfall with peaks in early and late summer, supplemented by frequent coastal mist, mean annual temperature of 16–18 °C, and mean daily temperature in the summer months (December–February) of 20–24 °C and in the winter months (June–August) of 14–16 °C ( Schulze et al. 2001). At a coarse scale, the habitat is mapped within the Albany Coastal Belt (AT 9) vegetation unit of the Albany Thicket Biome ( Hoare et al. 2006) and lies within the Albany Thicket Bioregion ( Cowling 2019).

Conservation status: — Crassothonna moniliformis is geographically localised and habitat-restricted, but is common where it occurs. The current known Extent of Occurrence and Area of Occupancy are <10 km 2. Accurate estimation of individual plant numbers is extremely difficult owing to the diffuse growth habit of the species. The known population is situated on unprotected communal land and is threatened by sand mining, trampling by communal livestock and encroachment from informal housing. The exposed pavements host several plant taxa of conservation concern, including Acmadenia kiwanensis Williams (1978: 347) (CR), Aspidoglossum flanaganii ( Schlechter 1894: 3) Kupicha (1984: 654) (DDD), Drimia chalumnensis Dold & Brink (2004: 631) (VU), Faucaria subintegra Bolus (1934: 449) (VU) and Lampranthus fugitans Bolus (1958: 330) (VU), as assessed in the Red List of South African Plants ( SANBI 2020). With reference to the IUCN Red List categories and criteria ( IUCN 2012), a conservation threat status of Vulnerable (VU – D2), applicable where a species is close to qualifying for or is likely to qualify for a threatened category in the near future, is recommended for Crassothonna moniliformis .

Etymology: —The species epithet is a compound adjective formed from the noun monīle (necklace) and the suffix - formis derived from the noun fōrma (shape), meaning ‘having the form of a necklace’. The epithet alludes to the slender trailing stems with regularly spaced, often bead-like leaves.

Illustrations: — Rowley (1994): 53, Fig. 61; 166, Fig. 253 (“ Othonna capensis ”).

Additional specimens examined (paratypes): — SOUTH AFRICA. Eastern Cape: Kidd’s Beach [3327 BA]: Dyam-Dyam , 7 August 2014, S. Moshani 107 ( GRA) ; Dyam-Dyam Village, Kiwane, between village and coast along Kiwane River , 3 October 2022, A. P. Dold 16065 ( GRA). Ex hort.: East London , Kayser’s Beach. Cultivated at Kirstenbosch ex Avonley farm [3327 BA], 20 June 1980, D. Gover s.n. ( NBG) .

Figures

FIGURE 2. Crassothonna moniliformis habitat and growth habit.A. Habitat (Dyam-Dyam, Eastern Cape). B. Growth habit. C. Flowering shoot. D. Capitulum. Photographs by A.P. Dold.

FIGURE 3. Comparison of Crassothonna species similar to Crassothonna moniliformis. A. Crassothonna moniliformis (Dyam-Dyam, Eastern Cape; Dold 16065, GRA). B, E, F. Crassothonna capensis (Redhouse, Eastern Cape; Dold 16068, GRA); C, G. Crassothonna capensis (commercial clone; McKenzie 3728, GRA). D, I. Crassothonna patula (Noupoort, Northern Cape; Dold s.n., GRA). H. Crassothonna patula (Joubert’s Pass, Eastern Cape). Bars = 10 mm (A–D). Photographs by R.J. McKenzie (A–D, F–I) & A.P. Dold (E).

FIGURE 4. Morphology of Crassothonna moniliformis. A. Habit. Bar = 2 cm. B. Disc florets, peripheral (left) and central (right). Corolla lobes are depicted as erect to show the abaxial surface. Bar = 1 mm. C. Ray floret, adaxial view. Bar = 2 mm. D. Involucral bracts (one bract of each morphological type is shown). Bar = 2 mm. E. Style of ray floret (left) and disc floret (right). Bars = 0.5 mm (left), 0.25 mm (right). F. Stamen (four not shown). Bar = 0.5 mm. G. Cypsela from ray floret, adaxial view. Bar = 2 mm. H. Pappus bristle of ray floret (left), peripheral disc floret (centre) and central disc floret (right). Bar = 1 mm. For visual purposes, not all pappus bristles are shown in B and C. Drawings by R.J. McKenzie.