Kalanchoe benbothae Gideon F.Sm. & N.R.Crouch, 2021

Smith, Gideon F. & Crouch, Neil R., 2021, Kalanchoe benbothae (K. subg. Fernandesiae; Crassulaceae subfam. Kalanchooideae), a new southern African species endemic to KwaZulu-Natal in the Maputaland-Pondoland Region of Endemism, Phytotaxa 521 (2), pp. 105-112 : 109-110

Kalanchoe benbothae Gideon F.Sm. & N.R.Crouch , sp. nov. ( Fig. 1A–E )

Type:— SOUTH AFRICA. KwaZulu-Natal province —2731 (Louwsburg): Vaalbank , (– CA), rocky grassland to northeast of town, sterile material collected in February 2017, flowered in cultivation in Durban, 2 June 2021, B . S . [Ben] Botha 1 (holotype PRU) .

Diagnosis:—Plants of Kalanchoe benbothae ( Fig. 1B ) are medium-sized to large, glabrous, densely waxy when young, bi- to triennial to perennial succulents that can be separated from K. luciae ( Fig. 2 ), its closest relative, as follows: Kalanchoe benbothae is less robust in all vegetative respects than K. luciae , with especially the leaves of the former (90–140 × 60–100 mm) not attaining the dimensions of the latter (40–160(–190) × 20–90(–110) mm) ( Fig. 1B ). The flowers of K. benbothae are lightly to moderately covered in a waxy bloom ( Fig. 1A ), while those of K. luciae have a substantial waxy bloom ( Fig. 2A–B ). The corolla lobes of K. benbothae are reddish pink and triangular, while those of K. luciae are white to pale yellowish green and oblong ( Fig. 1A, C–D ). The anthers of K. benbothae are reddish brown in bud, while those of K. luciae are yellow, and the pistil of the former is narrowly elliptic, whereas that of the latter species is prolate. Kalanchoe benbothae has transversely oblong nectar scales, while those of K. luciae are ± square ( Fig. 1E ).

Description:—Multiannual to perennial, few- to many-leaved, unbranched at first, pre- and/or post-flowering slowly sprouting from woody base, glabrous, waxy, medium-sized to robust succulent, 0.25–1.00 m tall when in flower. Stems light green to reddish-infused, unbranched, arising from sturdy base, erect to leaning, often with few indistinct, lengthwise running ridges. Leaves opposite-decussate, light green, infused with red to purplish red along leaf margins only, succulent, erect to slightly erectly spreading, coriaceous and papery-flimsy on drying; petiole absent, amplexicaul; blade 90–140 × 60–100 mm, obovate to broadly elliptic, somewhat gracefully and slightly folded upwards lengthwise, sometimes very slightly wavy, flat to slightly curved up along margins; base cuneate to narrowly triangular, sometimes very slightly auriculate; apex rounded-obtuse; margins smooth, slightly saucer-like curved upwards. Inflorescence erect to slightly leaning, apically dense, many-flowered, club-shaped to short-branched thyrse consisting of several dichasia terminating in monochasia, flowering portion 100–400(–700) mm long, branches opposite, rarely only one at node, erect to slanted away from main flowering stem at angle of 30°, subtended by leaf-like bracts, very rarely with leafy branchlets in axils, axis light green; pedicels 3–10 mm long, slender. Flowers erectly spreading to slanted horizontally to pendulous at anthesis; calyx light green to lightly reddish-infused, very densely white-waxy covered; sepals 4, ± 3–4 × 1.5–2.5 mm, narrowly triangular-lanceolate, succulent, clasping the corolla tube above, basally fused for 1.0– 1.5 mm, acute-tipped, contrasting against light yellowish green corolla tube; corolla 12–14 mm long, enlarged lower down, tapering to mouth, not twisted apically after anthesis; tube 11–13 mm long, light yellowish green, fading reddish brown when spent, narrowly urceolate, indistinctly 4-angled, round when viewed from below, longitudinally indistinctly fluted above; lobes (3–)5 × 3 mm, pink to reddish with margins often paler, triangular, tapering towards acute apex, margins slightly to distinctly in-folded, erecto-patent, rarely recurved, dark pink to red-tipped in bud. Stamens 8, inserted in two ranks, one rank just above middle of corolla tube, other well above middle of corolla tube towards mouth, all 8 slightly exserted to 1 mm, visible at mouth; filaments 2–4 mm long, light greenish white, thin, tapering upwards; anthers 0.5–0.6 mm long, yellow. Pistil consisting of 4 carpels, narrowly elliptic; carpels 6–7 mm long, dull mid-green; styles 1.5–2.0 mm long, dull mid-green; stigmas very slightly capitate, whitish green, positioned at mouth; scales ± 1 mm high, ± 2 mm broad, transversely oblong, flat to slightly tooth-like rounded and finely cockscomb-like pointed apically, uniformly light yellow. Chromosome number: unknown.

Distribution and habitat:—The earliest known material of K. benbothae was collected at Mooiklip near Louwsburg in 1936 by the indefatigable South African botanist Inez Clare Verdoorn (1896–1989), who was employed at the National Herbarium in Pretoria (Herb. PRE) from 1919 until 1951, and later (1967) was awarded an honorary Ph.D. degree by the University of Natal. The species was recently recollected.

This new species is known with certainty so far only from the type locality at Vaalbank in KwaZulu-Natal and also from Mooiklip some 20 km distant. However, based on sterile material it is considered to possibly occur also some 110 km to the north of Vaalbank at Iswepe, situated in KaNgwane Montane Grassland (Gm16) (David Styles pers. comm.; Mucina et al. 2006). The entire known natural geographical distribution range ( Fig. 3) of the species falls within the Maputaland-Pondoland Region of Endemism ( Van Wyk & Smith 2001: 82–85). Kalanchoe benbothae occurs in very shallow soils overlying dolomitic bedrock, in open grassland at elevations of ca. 1250 m, in Northern KwaZulu-Natal Moist Grassland (Gs4) and Northern Zululand Mistbelt Grassland (Gs 1) ( Mucina et al. 2006). It co-occurs with Aloe suprafoliata Pole Evans (1916: 603) and Aloe cf. minima Baker (1895: 153) [both Asphodelaceae ]. At the Vaalbank site some 50 plants have been observed, whilst at the unconfirmed Iswepe site ca. 30 plants were noted. The type locality is formally unprotected and subjected to grazing by cattle, whilst the original locality (Mooiklip) at which it was discovered, is presently threatened by coal mining activities.

Additional specimen examined:— SOUTHAFRICA. KwaZulu-Natal province [as “Natal”].—2731 (Louwsburg): Ngotshe, Mooiklip near Louwsburg (– CA), 30 July 1936, I. C . Verdoorn 1720 ( PRE!) .

Flowering time:— Kalanchoe benbothae flowers mainly in the winter months, May to August in the southern hemisphere, although in cultivation there as early as January.

Eponymy:— Kalanchoe benbothae is named for Mr B.S. (Ben) Botha (born 4 September 1961, Elliot, Eastern Cape Province, South Africa –), a nurseryman and succulent afficionado, especially of aloes across their global range. Ben Botha is apparently the first to have gathered material of K. benbothae since Inez Verdoorn collected it some 80 years earlier in 1936; he is credited for recognising it as distinct from K. luciae . Within the greater Durban region, KwaZulu-Natal, South Africa, Ben has been highly active in promoting waterwise gardening with succulents ( Fig. 1F ).

Figures

FIGURE 1. Kalanchoe benbothae from Vaalbank, KwaZulu-Natal, South Africa. A. Inflorescence section lateral view. B. Pseudo-rosette base of a flowering plant. C. Flower of K. benbothae (left) and K. luciae (right) lateral view. D. Flower of K. benbothae (left) and K. luciae (right) dorso-lateral view. E. Pistil with squamae of K. benbothae (left) and K. luciae (right). F. Ben Botha (1961–) for whom the species is named. Scale bars:A: 4 mm; B: 25 mm; C–D: 8 mm; E: 4 mm. Photographs by the authors (A–E) and B.A. Botha (F).

FIGURE 2. Kalanchoe luciae. A. Inflorescence section lateral view, close up showing dense waxy covering. B. Inflorescence section lateral view. C. Pseudo-rosette showing intensely red-infused leaves. D. Flowering plant colony, Botha’s Hill. Scale bars: A: 15 mm; B: 25 mm; C: 75 mm; D: 12 cm. Photographs by the authors.