Sekanama Speta

Martínez-Azorín, Mario, Crespo, Manuel B., Alonso-Vargas, María Ángeles, Pinter, Michael, Crouch, Neil R., Dold, Anthony P., Mucina, Ladislav, Pfosser, Martin & Wetschnig, Wolfgang, 2023, A generic monograph of the Hyacinthaceae subfamily Urgineoideae, Phytotaxa 610 (1), pp. 1-143 : 84-87

19. Sekanama Speta

in Stapfia 75: 168 (2001) ( Figs 47–48 ).

Typus generis:— S. sanguinea (Schinz) Speta (holotype).

Description:—Small to medium-sized bulbous geophyte. Bulb hypogeal, ovoid to subglobose, solitary, to 9 cm in diam., outer scales membranous and papery, inner scales red, compact. Roots thickened and branched. Leaves 2‒9 per bulb, mostly hysteranthous, 10‒40 cm long, suberect, narrowly lanceolate, canaliculated, green, leathery, glabrous, acute. Inflorescence racemose, from shortly racemose to elongated and multiflowered, 2‒60 cm long, with 25‒90 flowers; peduncle above ground level usually much shorter than inflorescence, erect, terete, glabrous, smooth; pedicels 4‒14 mm long, suberect to patent. Bracts oblong-obovate, navicular, lately caducous, 1‒3 mm long, with lanceolate-oblong spur, 0.5‒1.0 mm long; bracteoles present and small. Flowers shortly campanulate at base with spreading-patent upper 2/3 of tepals, erect-patent, diurnal. Tepals 6, biseriate, 7‒11 mm long, white with brownish or greenish longitudinal band more evident on abaxial side, mostly free, shortly connate at base to 2 mm long, papery and translucent when withered. Stamens 6, suberect or spreading, not connivent to style; filaments linear-lanceolate, 3‒7 mm long, white, adnate to perigone at base; anthers medifixed, oblong. Ovary ovoid, 2.0‒ 4.5 mm long, trigonous; style filiform, erect, 2.5‒4.0 mm long, white; stigma inconspicuously 3-lobed, papillate. Capsule ellipsoid to ovoid, 10‒18 mm long, valves completely dehiscing from base, withered tepals mostly persisting at base of dehisced capsule. Seeds ellipsoidal, 5‒10 mm long, flattened with prominent central embryo and wide, usually curved wings, testa black, glossy, with sinuous anticlinal cell walls.

Number of species and distribution:— Sekanama includes four species, occurring mainly in the inland regions of Southern Africa and extending to Tanzania and Socotra ( Fig. 49 ). They are restricted to the Southern and Eastern Sections of the Zambezian Subregion and the Erithreo-Arabian Subregion (sensu Takhtajan 1986 and Martínez-Azorín et al. 2023a). For further information in Sekanama see Jessop (1977), Speta (2001), and Manning & Goldblatt (2018).

Karyology:—2n=20 ( De Wet 1957, Jones & Smith 1967, as Urginea burkei Baker ).

History, diagnostic characters, and taxonomic relationships:— Speta (2001) described Sekanama to include Urginea sanguinea Schinz (1890: 219) , U. burkei Baker (1897: 469) , and U. delagoensis Baker (1897: 467) . This genus was characterised as having red bulbs with imbricate scales; proteranthous, straight leaves; racemose inflorescence with up to 70 flowers; shortly spurred bracts; pedicels 4‒9 mm long; and tepals 8‒10 mm long. The type of the genus, S. sanguinea , is one of the most poisonous plants in Africa due to its bufadienolides ( Krenn et al. 1993, Speta 2001). Urginea burkei has been treated as a synonym of U. sanguinea , and on the other hand U. lydenburgensis Dyer (1942b : t. 859) has been treated as a synonym of U. delagoensis ( Jessop 1977, Manning & Goldblatt 2018). In recent years, Drimia edwardsii Crouch & Martínez-Azorín (2015: 137) , which shares flower and fruit morphological traits with U. delagoensis and U. lydenburgensis , was described from central KwaZulu-Natal ( Crouch & Martínez-Azorín 2015).

The phylogenetic studies of Martínez-Azorín et al. (2023a) recovered three samples of S. sanguinea as a strongly supported clade. Another strongly supported clade combines samples of U. delagoensis , U. lydenburgensis , and D. edwardsii . These latter two clades are sometimes related as sister, although with very low support, whereas other analyses maintain them separate within general collapsed relationships. Important differences in morphology exist between S. sanguinea (including U. burkei ) and the remaining taxa in this group. Sekanama sanguinea is distributed in the inland regions of Southern Africa and is characterised by hysteranthous leaves, racemose inflorescences with peduncle much shorter than the raceme, white flowers, present bracteoles, withered tepals persisting at the base of the ovoid-ellipsoid capsule, and flat and wide, elliptic seeds. Conversely, U. delagoensis , U. lydenburgensis , and D. edwardsii are collectively distributed in eSwatini (formerly Swaziland), and in the adjacent South African provinces of KwaZulu-Natal and Mpumalanga. In terms of biochoria, they are restricted to the Uzambara-Zululand Region (sensu Takhtajan 1986). These latter three species have synanthous leaves, inflorescences with peduncles much longer than the raceme, absent bracteoles, pale brown or carneous to greenish flowers, withered tepals persisting at the top of the capsule, narrowly ellipsoid to fusiform capsules, and narrowly lanceolate-fusiform seeds.

The taxonomic revision by Manning & Goldblatt (2018) placed U. sanguinea in their D. sect. Macrocentrae J.C.Manning & Goldblatt, together with species such as Urginea macrocentra (= Boosia sensu Speta 2001 ), without taking cognisance of the phylogenetic work of Pfosser & Speta (2001, 2004), where these taxa nested in different and distant clades in the phylogeny, confirmed by the phylogenetic results of Martínez-Azorín et al. (2023a). Chromosome counts on Sekanama sanguinea (as Urginea burkei ) ( De Wet 1957, Jones & Smith 1967) found 2n=20, whilst the count on Urginea lydenburgensis R.A.Dyer by De Wet (1957) showed 2n=32, indicating clear chromosomal differences between Sekanama s.str. and Zulusia .

Based on our current data, we include U. delagoensis , U. lydenburgensis , and D. edwardsii in the new genus Zulusia Mart. -Azorín et al. Albeit with limited phylogenetic evidence, we include in Sekanama , Sekanama sanguinea (syn. S. burkei ) together with the endemic Tanzanian species Urginea brachystachys Baker (1892: 474) , Urginea johnstonii Baker (1898: 539) described from southern Angola, and the endemic Socotran Urginea porphyrostachys Baker ex Balfour (1884: 411) . This is based on their shared red and fleshy bulb scales, small and navicular bracts, presence of bracteoles, and the papery-translucent withered tepals mostly remaining at the base of developing capsules. Further studies are necessary to confirm species delimitations and genus circumscription.

Accepted species and required new combinations:—

Sekanama brachystachys (Baker) Mart. -Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Urginea brachystachys Baker in Bot. Jahrb. Syst. 15(4): 474 (1892), basionym ≡ Drimia brachystachys (Baker) Stedje in Nordic J. Bot. 7(6): 665 (1987) ≡ Urginavia brachystachys (Baker) Speta in Phyton (Horn, Austria) 38(1): 87 (1998) ( Fig. 4.7 ). Type:— TANZANIA. Musoma District, mile 5 from the Simiyu river, N.E. to the Eastern Boundary, S. Extension, elev. 5000 ft., 27 September 196?. P.J. Greenway 10211 (EA neo.; PRE!, K! iso.).

Sekanama johnstonii (Baker) Mart. - Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Urginea johnstonii Baker in Fl. Trop. Afr. [Oliver et al.] 7(3): 539 (1898), basionym ( Fig. 48.3 ). Type:— ANGOLA. Near the River Cunene, September 1893, Johnston s.n. (K000400576! holo.).

Sekanama porphyrostachys (Baker ex Balf.f.) Mart. -Azorín, M.B.Crespo & M.Á.Alonso comb. nov. ≡ Urginea porphyrostachys Baker ex Balf.f. in Proc. Roy. Soc. Edinburgh 12: 411 (1884), basionym ≡ Drimia porphyrostachys (Baker ex Balf.f.) A.G.Mill., Ethnofl. Soqotra Archipelago : 726 (385) (2004), nom. inval. ( Fig. 4.8 ). Type:— YEMEN. Socotra, inter Kischen, Pankoke, elev. 1000 ft., 02 May 1881, G. Schweinfurth 678 (K001044815! holo.).

Sekanama sanguinea (Schinz) Speta in Stapfia 75: 168 (2001) ≡ Urginea sanguinea Schinz in Verh. Bot. Vereins Prov. Brandenburg 31: 219 (1890), basionym ≡ Drimia sanguinea (Schinz) Jessop in J. S. African Bot. 43(4): 293 (1977) ( Figs 4.9 , 47 , 48.1–2 ). Type:— NAMIBIA. Gunib (2028): Osnambonde [Omambonde] in Nord-Hereroland, (–AA), October 1885, H. Schinz 25 (Z first-step lecto. designated as “holo.” by Manning & Goldblatt in Strelitzia 40: 19. 2018; second-step lecto. designated here:—Z000087336! lecto.; Z000027553!, K000257377! isolecto.). Note:—A second step lectotypification is needed due to the presence of two herbarium vouchers with different barcode numbers under the same collection.

= Urginea burkei Baker, Fl. Cap. (Harvey) 6: 469 (1897) ≡ Sekanama burkei (Baker) Speta in Stapfia 75: 168 (2001). Type:— SOUTH AFRICA. North West. Rustenburg (2527): Magaliesberg, (–CA, CC, DB, DC), September [without year], Burke s.n. (K000257374! lecto. designated by Jessop in J. S. African Bot. 43: 293. 1977; BM000911791! isolecto.).

= Urginea rautanenii Baker in Bull. Herb. Boissier ser. 2, 3: 664 (1903). Type:— NAMIBIA. Ondangua (1715): Amboland, Ondonga [Ondangwa], (–DD), 11 November 1895, M. Rautanen 171 (Z000027552! lecto. designated here; Z000027558! isolecto.).

Figures

FIGURE 4. Seed morphology in Urgineoideae. 1. Rhodocodon rotundus H.Perrier ex Knirsch et al.; 2. Rhodocodon siederi Knirsch et al.; 3. Rhodocodon urgineoides Baker; 4. Schizobasis intricata (Baker) Baker; 5. Schizobasis macowanii Baker; 6. Schizobasis sigmoidea (J.C.Manning & J.M.J.Deacon) Mart.-Azorín et al.; 7. Sekanama brachystachys (Baker) Mart.-Azorín et al.; 8. Sekanama porphyrostachys (Baker ex Balf.f.) Mart.-Azorín et al.; 9. Sekanama sanguinea (Schinz) Speta; 10. Squilla hesperia (Webb & Berthel.) Mart.-Azorín et al.; 11. Squilla maritima (L.) Steinh.; 12. Squilla palaestina (M.B.Crespo et al.) Mart.-Azorín et al.; 13. Squilla pancration Steinh.; 14. Squilla secundiflora (Maire) Mart.-Azorín et al.; 15. Squilla serotina (Schousb.) Mart.-Azorín et al.; 16. Squilla undulata (Desf.) Mart.-Azorín et al.; 17. Striatula oliverorum (J.C.Manning) M.Pinter et al.; 18. Striatula platyphylla (B.Nord.) M.Pinter et al.; 19. Tenicroa exuviata (Jacq.) Speta; 20. Tenicroa fragrans (Jacq.) Raf. All to the same scale in mm.

FIGURE 47. Sekanama sanguinea (Schinz) Speta from: 1. Pole Evans (1924: t. 138, as Urginea burkei Baker); 2. Stent & Curson (1922, as Urginea burkei Baker).

FIGURE 48. Species of Sekanama Speta displayed in horizontal rows of images. 1−2. Sekanama sanguinea (Schinz) Speta; 3. Sekanama johnstonii (Baker) Mart.-Azorín et al. (Photographs by T. Harvey from Kunene River in Angola).

FIGURE 49. Approximate distribution ranges of accepted genera in Urgineoideae.