Stenoglottis fimbriata var. modesta (Truter & Joliffe) D.P.Phillips & Bytebier, 2020

Phillips, Dean P. & Bytebier, Benny, 2020, A taxonomic revision of Stenoglottis (Orchideae, Orchidoideae, Orchidaceae), Phytotaxa 456 (3), pp. 219-243 : 228-230

1.2. Stenoglottis fimbriata var. modesta (Truter & Joliffe) D.P.Phillips & Bytebier , stat. nov. ( Figs 4–5 )

Basionym: Stenoglottis modesta Truter & Joliffe (2011: 12) , as S. modestus .

Type:— SOUTH AFRICA. KwaZulu-Natal: Vryheid, Lancaster Hill , 3 Jan 2009, Gibbon s.n. (holotype: PRU, 115533!) .

Diagnostic characters:— Stenoglottis fimbriata var. modesta is distinguished from the nominal variety by its leaves that are consistently entire and unspotted ( Fig. 4C ), minute vestigial spur ( Fig. 4E ), and distinctly trilobed labellum lacking additional fimbriation ( Fig. 4A–B, D ). For a detailed diagnosis of the varieties, see diagnostic characters under S. fimbriata var. fimbriata . In addition to the traits already discussed, in S. fimbriata var. modesta the inflorescence is often more notably sub-secund than in other Stenoglottis taxa, and the flowers may remain semi-closed even at anthesis. However, neither of the latter two characteristics was found to be consistent across all sampled populations. Stenoglottis fimbriata var. modesta is not likely to be mistaken for any of the other Stenoglottis species , but can nevertheless be distinguished by its acute side lobes, which in the remaining taxa are either broad and rounded ( S. woodii and S. macloughlinii ) or ligulate to broad and variously divided ( S. longifolia and S. inandensis ). It differs from all these species also in that its flowers are consistently self-pollinating and short-lived (usually beginning to close within ± 2 days of opening) and its stigmatic arms that are always erect in mature flowers ( Fig. 4F–G ), rather than forward-facing (i.e. approximately parallel to the labellum). Finally, despite its vestigial spur, it is not likely to be confused with any of the truly spurred species except perhaps, when not in flower, with S. woodii , which has essentially identical foliage.

Notes:— Most diagnostic characters described by Truter & Jollife (2011) for S. modesta are consistent throughout its geographic range. However, phylogenetic analyses ( Phillips & Bytebier 2020) has shown it to be indistinguishable from S. fimbriata (as circumscribed in this paper, including both subspecies and S. zambesiaca ) with which, in spite of its reliable diagnosis, it clearly shares overall morphological similarity. It seems that S. modesta recently diverged from S. fimbriata , and in view of the fact that it is sympatric (often in mixed populations) with S. fimbriata , it is better treated as an infraspecific taxon of that species. It is therefore reduced in rank here to S. fimbriata var. modesta .

Distribution and ecology:— Stenoglottis fimbriata var. modesta is known from several disjunct localities in the Eastern Cape and KwaZulu-Natal, South Africa ( Fig. 5 ), at elevations of 600–1300 m. It occurs in forests or forest margins, in deep or partial shade, most commonly as a lithophyte on mossy boulders, or on ledges and crevices along south-facing cliff faces, occasionally as a terrestrial in shallow soil. At several localities it has been found to cooccur with the nominal variety, with which it overlaps in flowering period but maintains its distinct form. It flowers February–April and is consistently self-pollinating.

Specimens:— SOUTH AFRICA. Eastern Cape: 3127 ( Lady Frere ): Engcobo, 1250 m (– DB) , 15 Feb 1912, McLoughlin 47a ( BOL 96149!, BOL 49893!) . 3128 (Umtata): Mnyolo , on road between Mnyolo and Ugie, 993 m (– AD) , 15 Jan 2017 (ex hort. Mar 2018), Phillips 50 ( BNRH!, NU0088387 !) ; Mnyolo, on Engcobo–Maclear road, Mnyolo Drift, 1113 m (– CB) , 27 Feb 1997, Dold 2896 ( GRA0005020 !) . 3225 (Somerset East): Somerset East , Stockenstroom, 609 m (– DD) , Mar 1887, Scully 690 ( BM000034617 !, BOL 49891!) . 3228 ( Butterworth ): Willowvale (– AD) , 25 Feb 1960, Van Breda 883 ( PRE0036813 -0!) . KwaZulu-Natal: 2730 (Vryheid): Vryheid Hill Nature Reserve , 1302 m (– DD) , 17 Mar 2016 (ex hort. Mar 2018), Phillips 28a ( NU0088333 !) ; Vryheid Nature Reserve (– DD) , 16 Mar 1988, Youthed 219 ( CPF0021093 !) . 2929 (Underberg): Estcourt, Moor Park Nature Reserve (– BB) , 19 Feb 1999, Scott-Shaw 9441 ( CPF0021100-1 !) ; Estcourt, Moor Park Nature Reserve (– BB) , 19 Feb 1999, Scott-Shaw 9446 ( CPF0021100 !) . 2930 (Pietermaritzburg): Howick, Umgeni Valley Nature Reserve , 951 m (– AC) , 9 Mar 2016, Phillips 24 ( NU!) ; New Hanover, Fawn Leas , 931 m (– BD) , 10 Mar 2016, Phillips 25 ( NU!) ; Pietermaritzburg (– CB) , Mar 1932, Carnegie NBG356/31 ( BOL 49914!) ; Cumberland Nature Reserve , in forested gorge next to path leading to top of big waterfall, 614 m (– DA) , 13 Jan 2016, Phillips 1 ( NU!) ; Cumberland Nature Reserve , in forested gorge next to path leading to top of big waterfall, 608 m (– DA) , 13 Jan 2016 (ex hort. Mar 2018), Phillips 2 ( NU0088308 !) ; Inanda (– DB) , 1880 Wood 854 ( BOL 50012!) ; Ismont , 609 m (– DC) , Apr 1883, Wood 24 ( PRE0036824 -0!, SAM0020466 !). 3030 ( Port Shepstone ): Ixopo, Langefontein Farm, 748 m (– AA) , 14 Jan 2016 (ex hort. Mar 2018), Young & Phillips 2477 ( BNRH!, NU0088301 !) .

Figures

FIGURE 4. Selected specimens of Stenoglottis fimbriata var. modesta. A, inflorescence, Fawn Leas (KZN). B, flowers ventral view, Mnyolo (EC). C, habit (in situ), Vryheid Hill Nature Reserve (KZN). D–E, flowers ventral and lateral view (showing vestigial spur and sheathing bract), Vryheid Hill Nature Reserve (KZN). F–G, column ventral and lateral view, Ixopo (KZN). Scale bars = 5 mm (A–B, D– E), 0.5 mm (F–G).Abbreviations: au = auricle, an = anther, stg = stigmatic arm. C reproduced with the permission of Herbert Stärker.

FIGURE 5. Distribution of Stenoglottis fimbriata var. modesta.