Lachenalia komsbergensis G.D.Duncan, 2023

Duncan, Graham D., 2023, Four new species and three taxonomic adjustments in Lachenalia (Asparagaceae: Scilloideae) from southern and western South Africa, Phytotaxa 585 (4), pp. 261-273 : 262-265

Lachenalia komsbergensis G.D.Duncan , sp. nov. ( Figs. 1 , 2 )

Type:— SOUTH AFRICA. Northern Cape: Komsberg Pass, 2.1 km north of entrance to farm De Plaat on R354 from Matjiesfontein to Sutherland (3220 DC), solitary plants and scattered clumps on flats among low scrub, in deep, beige alluvium above dry riverbed, in full sun, elev. 1144 m, 8 October 2001, Duncan 459 (holotype NBG) .

This new species differs from L. juncifolia Baker (1871: 409) in its leaves that are deeply canaliculate for their entire length, its spreading, white perianth with narrowly spreading stamens, its slightly larger globose seeds (1.2–1.3 × 1.3–1.4 mm) with a matt black testa and rugose primary sculpturing, a longer strophiole 0.5–0.6 mm long, and in its taller stature up to 300 mm high in full flower.

Deciduous, winter-green geophyte 150–300 mm high. Bulb subglobose, 15–20 mm in diam., offset-forming (1 or 2 offsets formed per bulb, but not necessarily every year); tunic multi-layered, outer tunics spongy, dark brown, inner tunics membranous, light brown; cataphyll translucent white, adhering to leaf bases, apex obtuse. Leaves 2, linear, 200–260 × 1–15 mm, suberect or recurved, deeply canaliculate, upper surface light green, lower surface light green in upper two thirds, heavily magenta- or purple-barred in lower third; apex acute; primary seedling leaf terete, erect. Inflorescence racemose, 10–48-flowered, flower head 40–120 mm long; peduncle erect to suberect, 100–155 mm long, rigid, light green, heavily speckled with dull purple; rachis light green and heavily purple-speckled in lower two thirds, white in upper third; lower bracts ovate, 1–4 × 2–3 mm, upper bracts lanceolate, 1–2 × 1 mm, white; pedicels suberect, 5–10 mm long, white. Perianth zygomorphic, oblong-campanulate, suberect; tube cup-shaped, 3 mm long, white; outer tepals ovate, 4–5 × 3–4 mm, apices flat, apical gibbosity deep pink; inner tepals obovate, 5–7 × 3–5 mm, translucent white, median keel light green in upper half, apices recurved. Stamens well exserted, narrowly spreading; filaments 8–10 mm long, white; anthers 0.8–1.0 mm long, pollen yellow. Ovary obovoid, 3 × 2 mm, light green; style well exserted, straight, 9–10 mm long, white; stigma minutely capitate. Capsule obovoid, 6–7 × 4–5 mm. Seed globose, 1.2–1.3 × 1.3–1.4 mm, matt, black; primary sculpturing rugose; strophiole 0.5–0.6 mm long, ridged. Flowering time: September to October.

Etymology:— The specific epithet komsbergensis commemorates the Komsberg in the southern Great Karoo, to which this species is endemic.

Other material examined:— SOUTH AFRICA. Northern Cape: Komsberg Pass , 2.1 km north of entrance to farm De Plaat on R354 from Matjiesfontein to Sutherland (3220 DC) , solitary plants and scattered clumps on flats among low scrub, in deep, beige alluvium above riverbed, in full sun, elev. 1144 m, 1 September 2000, Summerfield s.n. ( NBG) ; Komsberg Pass, farm Damslaagte (3220 DC) , at river crossing, 19 October 2008, Saunders & Manning 3196 ( NBG) .

Notes:— The first collection of flowering specimens was made at the type location by G.C. Summerfield in September 2000. A subsequent record of flowering plants was made at the same location by G.D. Duncan on 8 October 2001 , when the type specimens were collected and habitat photographs were taken. Material from this collection has since flowered every year in cultivation in the bulb nursery at Kirstenbosch. A third collection at late flowering stage was made close to the type location by R. Saunders and J. Manning on 19 October 2008.

Diagnostic features and affinities:— Lachenalia komsbergensis is recognised in flower by an erect or suberect, rigid, light green peduncle that is heavily speckled with dull purple, bearing a raceme of small oblong-campanulate, spreading, white and pink flowers carried on white, suberect pedicels ( Fig. 1 A ). It has shallowly cup-shaped perianth tubes and narrowly spreading tepals. The outer tepals have a prominent deep pink median keel and apical gibbosity, and the strongly protruding inner tepals have a dull pink median keel. The flowers have bracts that are ovate at the base of the inflorescence and lanceolate above, and well exserted, narrowly spreading, white stamens. The inflorescence emerges towards the end of the growing season, as the leaves start to wither. The species is further recognised by two linear, suberect or recurved, deeply canaliculate, conduplicate leaves, with acute apices. The upper and lower surfaces are light green, and the lower surfaces are heavily magenta- or purple-barred in the lower third, and green-barred in the upper two thirds. The primary seedling leaf is terete, with erect orientation. The fruit is an obovoid capsule containing globose, matt black seeds with rugose primary sculpturing, and ridged strophioles.

Lachenalia komsbergensis is included within subsect. Lachenalia of sect. Lachenalia ( Duncan et al. 2022) . It was initially considered to be a tall-growing form of L. juncifolia , but in phylogenetic analysis it was retrieved as sister to two accessions of L. longibracteata Phillips (1931: 405) , in a phylogenetically strongly isolated position from L. juncifolia , the latter falling within sect. Linearifoliae ( Duncan et al. 2022). L. komsbergensis differs from L. juncifolia in having leaves that are deeply canaliculate for their entire length (versus slightly canaliculate in the lower two thirds and terete in the upper third), a spreading, mostly white perianth (versus cernuous and cream-coloured, pink, magenta or purple), narrowly spreading stamens (versus straight), a taller stature up to 300 mm high (versus up to 200 mm high), slightly larger seeds (1.2–1.3 × 1.3–1.4 mm) with a matt black testa and rugose primary sculpturing (versus 1.1– 1.2 × 1.3 mm, with a glossy black testa and smooth primary sculpturing), and a substantially longer strophiole 0.5–0.6 mm long (versus 0.2 mm long). Furthermore, L. juncifolia has a much longer flowering period (August to December) and a much wider distribution from Calvinia in the western Great Karoo to Herbertsdale in the southern Cape ( Duncan 2012).

Distribution and habitat:— Lachenalia komsbergensis occurs in the Succulent Karoo biome in the southern part of the Northern Cape, and is endemic to the Komsberg, a component of the Hantam-Roggeveld Centre of Plant Endemism ( Van Wyk & Smith 2001, Mucina & Rutherford 2006, Clark et al. 2011). It is highly localised to open flats adjacent to a seasonal river in the southern Komsberg, at an elevation of 1144 m ( Fig. 2 ). The area receives most of its rainfall in winter but is transitionary between winter and summer rainfall regimes ( Clark et al. 2011). The plants occur as scattered solitary individuals or in small groups of up to four plants on flats in deep, beige alluvium. The bulbs are shallowly seated and occur among low, sparse, scrubby vegetation including perennials of the family Asteraceae , in Central Mountain Shale Renosterveld, a vegetation type which occupies a borderline position straddling the Fynbos, Succulent Karoo and marginally the Nama Karoo biomes ( Mucina & Rutherford 2006) ( Fig. 1 B, C ). The species flowers late in the spring season (late September to October), at a time when the leaves are already beginning to desiccate.

Figures

FIGURE 1. Lachenalia komsbergensis: detail of three flowering racemes in cultivation (A); single plant flowering in beige alluvium, Komsberg Pass (B); general view of Central Mountain Shale Renosterveldhabitat, Komsberg Pass (C).Lachenalia inflata: single flowering plant in red sand north of Middelpos (D); single flowering plant in red clay west of Calvinia (E); general view of Roggeveld Karoo habitat north of Middelpos (F). Lachenalia granitica: detail of flowering spike in cultivation, with arrow showing a very long bract (G); flowering plant from Vredenburg in cultivation (H); spike of flowering and fruiting plant in Saldanha Granite Strandveld habitat near Vredenburg (I). Lachenalia filamentosa: flowering plants from Riviersonderend in cultivation (J); single flowering plant from De Hoop Nature Reserve in cultivation (K); two plants in early fruiting stage in De Hoop Limestone Fynbos habitat, De Hoop Nature Reserve (L). Photographs: A-D, F-K by Graham Duncan; E by Adam Harrower; L by David Gwynne-Evans.

FIGURE 2. Distribution of Lachenalia komsbergensis in the southern Great Karoo of the Northern Cape, South Africa (inverted black triangle), Lachenalia inflata in the western Great Karoo, Northern Cape, South Africa (black triangles), Lachenalia granitica along the Cape West Coast, Western Cape, South Africa (black squares) and Lachenalia filamentosa along the Cape West Coast, Breede River Valley and Overberg in the Western Cape, South Africa (black dots).