Orchidaceae), a New Orchid from the Western Cape of South Africa ⁎ B
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Available online at www.sciencedirect.com South African Journal of Botany 73 (2007) 558–562 www.elsevier.com/locate/sajb Disa linderiana (Orchidaceae), a new orchid from the Western Cape of South Africa ⁎ B. Bytebier a, , E.G.H. Oliver b, W.R. Liltved c a Biochemistry Department, Stellenbosch University, Private Bag X1, Stellenbosch 7062, South Africa b Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa c Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa Received 23 February 2007; accepted 25 April 2007 Abstract Disa linderiana, a new species belonging to Disa sect. Disella, is described from the high mountains of the western part of the Cape Floristic Region, South Africa. It is most closely related to Disa tenuicornis on account of the shortly bisaccate galea and narrow subpendent spur. © 2007 SAAB. Published by Elsevier B.V. All rights reserved. Keywords: Cape flora; Cederberg; Disa; New species; Orchidaceae 1. Introduction et al.). Here we describe a new species that belongs to this particular section. The large African orchid genus Disa P.J.Bergius, and the subtribe Disinae to which it belongs, have been the subject of 2. Species treatment considerable taxonomic attention. Linder (1981a,b,c,d,e) re- vised the group and recently Bytebier et al. (2007) published a Disa linderiana Bytebier and E.G.H.Oliv., sp. nov., ad sect. molecular phylogenetic analysis based on a 70% sampling of all Disellam Disae pertinens intra quam D. tenuicornis Bolus taxa, which found many similarities with the infrageneric propter saccas duabas posterioribus cum calcare pendente classification proposed by Linder (1981c) and Kurzweil and angusto similissima sed partibus vegetatis plerumque rubes- Linder (2001), but also some differences. As a result of this centibus, inflorescente densiore, floribus parvioribus, bracteis work, section Disella Lindl. sensu Linder and Kurzweil (1999) prominentibus crassis longioribus apicibus erectis distinguitur. was extended with the inclusion of D. elegans Sond. ex Rchb.f. TYPUS.—Western Cape Province, 3219CA, Cederberg and D. bodkinii Bolus, both formerly placed in section Disa. Wilderness Area, upper W–WSW-facing slopes of Sneeuberg, Section Disella currently contains 18 taxa, one of which 1860 m, 20 November 2006, Bytebier B, Liltved W, Oliver (D. remota H.P.Linder) was described only recently (Linder EGH, Oliver TA, Sakwa J and van Rooi J 2728 (BOL, holo; and Hitchcock, 2006). Section Disella is endemic to the Cape NBG, iso). Floristic Region. The study of this section is hampered by the Plant herbaceous with erect robust stem, 90–160 mm tall fact that plant material is hard to come by, as most species flower above ground, sheathing leaf bases imbricate, beetroot-red, only the first year after fire. Indeed, several species are only underground portion of the stem 40–65 mm long, covered with known from the type collection (D. remota, D. cedarbergensis fibrousremnantsofpreviousseason'sleaves.Tubers 2, H.P. Linder) or only from the type locality (D. subtenuicornis ellipsoid, ±25×10 mm. Leaves all cauline, rigid to lax, 7–10, H.P.Linder, D. brevipetala H.P.Linder, D. introrsa Kurzweil lanceolate to linear-lanceolate, acute to acuminate, with loose sheathing bases, 75–160×10 mm, grading apically into floral bracts; lowest leaf noticeably longer and wider, 135×16 ⁎ Corresponding author. (−215×19) mm, narrowly spathulate, acute, glabrous, green E-mail address: [email protected] (B. Bytebier). with only sheathing base beetroot-red, or green suffused with 0254-6299/$ - see front matter © 2007 SAAB. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.sajb.2007.04.066 B. Bytebier et al. / South African Journal of Botany 73 (2007) 558–562 559 beetroot-red to totally beetroot-red. Inflorescence obovoid to shortly but distinctly bisaccate galea with a rather narrow ellipsoid, dense, 50–60 mm long, with 20–25 flowers; bracts subpendent spur. It differs in producing shorter more compact erect, apically incurved; the lowest lanceolate–acuminate, plants with a denser and shorter inflorescence; and by the canaliculate, 30×4 mm, longer than the flowers, smaller vegetative parts being nearly all beetroot-red in colour, at least towards the apex of the inflorescence; upper narrowly elliptic- initially; by the stouter, broader, short leaves; by the smaller acute, ±6×2.5 mm, just longer than ovary; all glabrous but flowers which tend to face outwards and often sideways rather shallowly colliculate to minutely strigulose abaxially, more so than downwards and almost horizontal; by bracts which are to margins, remaining fleshy, beetroot-red. Flowers resupinated, prominent and longer than the flowers in the lower part of the spreading, facing outwards to downwards, sometimes slightly inflorescence and remaining fleshy with an erect apical half, and sideways, becoming erect and more or less suffused with by being not deflexed, dried out and brown. beetroot-red colour in fruiting stage; dorsal sepal shallowly The species has some similarities to the recently described galeate, ±6.5–8 mm long, 4.5–6 mm wide and 3 mm deep, D. remota from the Hex River Mountains. That species has dorsally slightly flattened near apex and base otherwise broadly larger open flowers, a very shallowly saccate galea, prominent rounded; mouth at 45°, broadly elliptic to slightly obovate crenulate anterior lobes to the petals and two distinct suberect in front view; apex broadly rounded to slightly emarginate, lobes at the base of the lip. D. remota could be more closely apiculus slightly upward-turning, greenish; glabrous, smooth to related to D. subtenuicornis in sharing with it the lip with two slightly colliculate down dorsal region, white laterally, greener towards dorsal and posterior areas and lightly beetroot-red dorsally at posterior end, with longitudinal darker dorsal stripe and with 4–8 dark beetroot-red maculae on the inside showing through to the outside, with 2 posterior pouches on either side of the spur protruding 0.3–0.5 mm and 1 mm wide, greenish; spur pendent in same arc as the dorsal surface of galea, 3–3.3×0.7– 0.8 mm, ±cylindrical, truncate-rounded, glabrous; lateral sepals spreading, distally decurved, ±6.4×4 mm, broadly falcate–ovate sometimes almost rectangular in basal half, apically obtuse, subapically slightly canaliculate (indented), abaxially keeled, the keel ending in a subapical apiculus, adaxially white sometimes tinged pale green with 1 or 2 pale beetroot-red small maculae and very narrow darker beetroot-red margins, abaxially totally beetroot-red, the keel darker, overall glabrous and minutely colliculate; petals 2-lobed, reflexed, horizontal, 3.5–4 mm long, oblong, geniculate, white, subfle- shy, glabrous, attached to rostellum by a slender lateral flange; anterior lobe flanking the stigma, ±1.4 mm tall, 2.5 mm in diameter, ±semicircular, upper margin entire, reddish; posterior lobe enclosing the apex of the anther, ±2.2 mm tall, ±0.3 mm across in mid-region, narrowly triangular, erect and obliquely set above the basal green knee-joint, with white tip and beetroot-red mid-region; lip lanceolate, ±5.5×1.5 mm, strongly arcuate, subfleshy, glabrous, white with green tip. Rostellum 2- lobed, lobes erect to slightly pointing backwards but pointing forwards in late flowering, ±1.2×1.1 mm, canaliculate, ending in 2 separate globular viscidia, with a small lateral auriculate appendage projecting±0.2 mm on either side of rostellum. Anther±2×0.8 mm, ovoid, pendent or reflexed to 135°, becoming almost horizontal in late flowering stage, held between rostellum and knee-joint of posterior petal lobe. Stigma erect, shortly columnar, ±1.4 mm wide, 1.3 mm deep and 0.8 mm tall, white to pale greenish. Ovary±11 mm long, Fig. 1. Analytical drawings of Disa linderiana, all drawn from the type ellipsoid-cylindrical, green tinged beetroot-red, glabrous. (Figs. collection. Scars where organs have been removed are cross-hatched. (A) whole 1 and 2). flower, semi-lateral view; (B) flower, lateral view; (C) flower, front view; (D) galea, back view showing spur and two basal saccae; (E) lefthand lateral 3. Diagnostic characters and relationships sepal, adaxial view; (F) lip, adaxial view; (G) petal, adaxial view showing the posterior erect lobe with basal knee-joint; (H) (on right) rostellum and anthers flanked by petals, front view with posterior lobe of each petal behind the Within section Disella D. linderiana is most closely related rostellary arms; (on left) columnar stigma, rostellum and oblique anthers, lateral to D. tenuicornis (Fig. 3) on account of the shared character of a view. Scale bar: 6 mm for A–D; 3 mm for E–H. Del. E.G.H. Oliver. 560 B. Bytebier et al. / South African Journal of Botany 73 (2007) 558–562 Fig. 2. Disa linderiana.—(A) plant in situ on Sneeuberg, most lower leaves eaten (note crab spider on the basal part of plant) (photograph T.A. Oliver); (B) close-up of flowers (photograph E.G.H. Oliver); (C) shade form showing elongate leaves and the longer, broader, basal leaf to the left, most flowers erect and in fruiting stage (Bytebier et al. 2728, isotype) (photograph W.R. Liltved); (D) plant in situ on the Great Swartberg (Vlok 1273) (photograph J.H.J. Vlok). basal lateral lobes and the lack of a distinctly bisaccate galea, D. longifolia are more slender with the stems more elongate but the latter has a very distinctive bilobed posterior lobe to the giving the plants a more clavate shape and the vegetative parts petals. All these characters also serve to distinguish it from our are green rather than beetroot-red. Two extraordinarily tall new species. herbarium specimens from the Hex River Valley (Tyson 644, In overall appearance D. linderiana also bears some October 1881, in BOL) prove D.