Stenoglottis inandensis, G.McDonald & D.G.A.Styles, 2008

Phillips, Dean P. & Bytebier, Benny, 2020, A taxonomic revision of Stenoglottis (Orchideae, Orchidoideae, Orchidaceae), Phytotaxa 456 (3), pp. 219-243 : 234-236

3. Stenoglottis inandensis G. McDonald & D.Styles in McDonald (2008: 10). ( Figs 8–9 )

Type:— SOUTH AFRICA. KwaZulu-Natal: Inanda Mountain, inland of Durban , overlooking Inanda Dam , 23 Apr 2005, Styles & McDonald 2613 (holotype: NU, 0016075!) .

Lithophytic or terrestrial. Leaves 6–10, lanceolate to linear, concolourous green or sparsely spotted with brown or maroon, margins flat, entire, up to 12.0 × 1.8 cm. Inflorescence up to 48 cm tall, with 15–30 flowers; sheaths unspotted. Bracts cordate, acute to acuminate, unspotted, sheathing or recurved, always shorter than the ovaries, 6.0–8.0 × 2.3–5.0 mm. Flowers white to pale pink, often spotted with a darker shade of pink or purple on all parts or labellum only; not self-pollinating. Sepals ovate, acute to obtuse, dorsal concave, laterals oblique, 5.0–7.5 × 2.7–5.5 mm, subequal. Petals ovate, oblique, acute, 4.2–6.5 × 3–4.5 mm. Labellum spurred; oblong to obovate in outline, 8.6–18 × 4.2–7.4 mm; side lobes shallowly incised to deeply divided; midlobe attenuate, longer than or subequal to side lobes; spur saccate, 1.4–3.2 mm × 0.8–1.4 mm at the apex, without nectar. Column up to 2.5 mm long; stigmatic arms suberect or parallel to labellum in mature flowers, curving outward; auricles clavate, up to 0.8 mm × 0.6 mm at the apex, projecting beyond the anther between the pollinia and stigmas. Ovary 12–22 mm long.

Diagnostic characters:— Stenoglottis inandensis is easily distinguished from S. fimbriata and S. longifolia by its spur ( Fig. 8D, F–G ). It does not overlap geographically with S. macloughlinii , but in any case could be easily distinguished by differences in their spurs: saccate and without nectar in S. inandensis versus tapered and nectarproducing in S. macloughlinii . Stenoglottis inandensis is most likely to be mistaken for S. woodii , with which it overlaps in both geographic distribution and flowering period. They can be distinguished by differences in their spur, labellum and leaf morphology. The spurs of S. inandensis are generally longer (1.4–3.2 mm) than those of S. woodii (0.4–1.5 mm), as well as being more notably saccate in shape (i.e. bulging at the apex). Only one population of S. woodii , from Fields Hill, Pinetown, was found to have spurs as long as those of S. inandensis . The side lobes of S. inandensis always exhibit some degree of additional fimbriation, although the fimbriae vary considerably in length ( Fig. 8A, C, E ), whereas the side lobes of S. woodii are broad, rounded to truncate and almost always entire. The labellum midlobe in S. inandensis is slender with a sharply pointed tip, whereas in S. woodii it tends to be broader with a more obtuse apex. Finally, the bracts of S. inandensis may be sheathing or recurved ( Fig. 8G ) and leaves unspotted to sparsely spotted with brown or maroon ( Fig. 8H ), whereas in S. woodii the bracts are always sheathing and leaves are never spotted.

Notes:— Stenoglottis inandensis is morphologically and phylogenetically distinct from the other spurred taxa. It is a rare and locally restricted species that was previously known (from herbarium records) only from the type locality at Inanda Mountain; the population at Table Mountain (~ 25 km northwest of Inanda Mountain and ~ 15 km east of Pietermaritzburg, KwaZulu-Natal) was previously regarded as S. woodii . However, a specimen from this locality (Phillips 22) included in the phylogenetic analysis of Phillips & Bytebier (2020) was sister to S. inandensis accessions from Inanda Mountain (Young 2510 and Young 2512). Collectively, the phylogenetic position of these populations is closer to the spurless S. fimbriata and S. longifolia than to the clade containing S. woodii and S. macloughlinii . The plants from the Table Mountain population also share several morphological characteristics (see ‘diagnostic characters’) with the Inanda Mountain plants that collectively distinguish them from the other spurred species. Consequently, the circumscription of S. inandensis has been expanded here to encompass this population.

Distribution and ecology:— Stenoglottis inandensis is restricted to KwaZulu-Natal, South Africa, where it is known from several scattered colonies on Inanda Mountain and Table Mountain ( Fig. 9 ) at elevations of 600– 900 m. It occurs in forests or forest margins in deep or partial shade, most commonly as a lithophyte on boulders or on ledges and crevices along south-facing cliff faces, occasionally as a terrestrial in shallow soil. It flowers January–April and is not self-pollinating.

Specimens:— SOUTH AFRICA. KwaZulu-Natal: 2930 (Pietermaritzburg): Table Mountain , 823 m (– DA) , 13 Jan 1949, Killick 244 ( NU0010115 !) ; Table Mountain , 897 m (– DA) , 1 Mar 2016 (ex hort. Mar 2018), Phillips 22 ( NU0088329 !) ; Inanda Mountain, inland of Durban , 650 m (– DB) , 17 Feb 2016, Styles 5268 ( NH0141061 -0!); Inanda Mountain , overlooking Inanda Dam, 636 m (– DB) , 19 Jan 2016 (ex hort. Mar 2018), Young et al. 2510 ( NU0088303 !) ; Inanda Mountain, overlooking Inanda Dam , 636 m (– DB) , 19 Jan 2016 (ex hort. Mar 2018), Young et al. 2511 ( NU!) ; Inanda Mountain, overlooking Inanda Dam , 635 m (– DB) , 19 Jan 2016 (ex hort. Mar 2018), Young et al. 2512 ( BNRH!, NU0088304 !, NU0088305 !) .

Figures

FIGURE 8. Selected specimens of Stenoglottis inandensis. A, flowers, Inanda Mountain (KZN). B–D, inflorescence, flower ventral view and spur close-up, Table Mountain (KZN). E–H, flower ventral view, spur close-up, flower lateral view (showing spurred labellum and recurved bract) and leaf rosettes (cultivated), Inanda Mountain (KZN). I–J, column lateral and ventral view, Inanda Mountain (KZN). Scale bars = 5 mm (A–C, E, G), 2 mm (D, F), 0.5 mm (I–J). Abbreviations: au = auricle, an = anther, stg = stigmatic arm.

FIGURE 9. Distribution of Stenoglottis inandensis.