Litanthus Harv., 1844

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 : 62-63

12. Litanthus Harv.

in London J. Bot. 3: 314, t. 9 (1844) ( Fig. 33 ). Typus generis:— L. pusillus Harv. (holotype). ≡ Drimia sect. Litanthus (Harv.) J.C.Manning & Goldblatt in Strelitzia 40: 150 (2018). Typus sectionis:— L. pusillus Harv. (holotype).

Description:—Dwarf bulbous geophyte. Bulb hypogeal or slightly epigeal, sometimes proliferous and clump forming, ovoid to subglobose, up to 1 cm in diam., outer scales scarious and inner scales white to pinkish, fleshy. Roots thickened and branched. Leaves 1‒5, filiform, subterete, 1‒10 cm long, 0.2‒1.0 mm wide, suberect, green, glabrous, hysteranthous or synanthous. Inflorescence formed by 1(‒2) teminal flowers; peduncle erect, terete, minutely papillate, 1–8 cm long, greenish to purplish; pedicels 1–3 mm long at anthesis, recurved, erect in fruit to 8 mm long. Bracts lanceolate, usually two, terminal, subopposite, commonly only one with flower, ca. 1 mm long, with spur ca. 0.5 mm long; bracteoles absent. Flowers tubular, nodding. Tepals 6, 4‒7 mm long, whitish with pinkish, brownish or purple tinge, fused for most of their length to form cylindrical tube ending in short apical erect or spreading lobes, with distinct greenish or brownish longitudinal band. Stamens 6, included in perigone tube; filaments adnate to tepals and arising around middle of perigone, free portions very short, ca. 0.5 mm long, flattened, white, smooth; anthers oblong, 1‒2 mm long, erect, opening by longitudinal slits, cordate at base, connective extended at apex into membranous flap. Ovary ovate-oblong, 1.5‒3.0 mm long, greenish to yellowish. Style erect, columnar, 2.0‒ 3.5 mm long, white, with subcapitate stigma ending in 6 erect lobes. Capsule subglobose, ovate or oblong, trigonous with blunt edges in section, 3‒6 mm long, from uniformly pale brown to longitudinally banded brown and white. Seeds trigonous, narrowly pyramidal, pointed, 0.5–1.5 mm long, embryo prominent with very narrow winged margins, black, glossy, with rugose testa and subisodiametric and polygonal testa cells.

Number of species and distribution:— Litanthus includes two species occurring in Southern Africa (Manning et al. 2013) ( Fig. 29 ), restricted to the Cape, Karoo-Namib, Uzambara-Zululand Region, and the Southern Section of the Zambezian Subregion (sensu Takhtajan 1986 and Martínez-Azorín et al. 2023a). For further information on Litanthus species see Harvey (1844) and Manning et al. (2013).

Karyology:—2n=20 ( Bruyns & Vosa 1987, as Litanthus pusillus Harv. ).

History, diagnostic characters, and taxonomic relationships:— Litanthus was described by Harvey (1844) as monotypic to include L. pusillus Harvey (1844: 315) , a distinct dwarf species with 1(–2)-flowered inflorescence, two subopposite spurred bracts, nodding, tubular flowers with tepals connate into a long tube, and included stamens with adnate very short filaments. This genus has been accepted by most researchers working in Urgineoideae ( Baker 1871, Hooker 1872, Jessop 1977, Speta 1998a, 1998b, Martínez-Azorín et al. 2015). However, Goldblatt & Manning (2000), Manning et al. (2004), and Manning & Goldblatt (2018) included Litanthus in Drimia sensu lato. Manning et al. (2013) presented a revision of Litanthus (as a group of Drimia ) and described a second related species. They added useful diagnostic characters for the genus, such as the usually solitary flower with a second empty bract and the elongation of the anther connective into a small, translucent, membranous flap. Further, they described and illustrated the characteristic stigma of both species, unique among Urgineoideae in possessing six tiny, erect teeth. The latest revision of Urgineoideae in Southern Africa ( Manning & Goldblatt 2018) placed L. pusillus and L. stenocarpus (J.C.Manning & J.M.J.Deacon in Manning et al. 2013: 99) Mart.-Azorín et al. (2015: 168) in Drimia sect. Litanthus ( Harvey 1844: 314) Manning & Goldblatt (2018: 150) .

The phylogenetic studies by Manning et al. (2004) show a sample of Litanthus pusillus as an independent lineage within a large collapsed clade. Pfosser & Speta (2001, 2004) recovered a sample of L. pusillus and Schizobasis as sister groups. Pfosser et al. (2012) found the same relationship following the inclusion of three samples in each genus. The phylogenetic analyses of Martínez-Azorín et al. (2023a) considered four samples of Litanthus , which form a strongly supported clade sister to the monophyletic Schizobasis , for which eleven samples were included in the analyses. The sister relationship between Litanthus and Schizobasis , at first sight surprising when based on their different flower and inflorescence morphology, is supported by the apiculate connective or the angled seeds, as shown by Manning & Goldblatt (2018). However, merging these genera in a single genus would be highly disruptive due to their distinct differences in flower and inflorescence morphology. Therefore, we accept Litanthus based on its unique syndrome of morphological characters: very small plant size; usually solitary, nodding flowers; tepals connate for at least half of their length in a cylindrical tube; stamens included with adnate filaments arising from the upper half of perigone, and apiculate connetive; stigma with 6 minute, erect teeth; seeds angular, polygonal, narrowly pyramidal, ca. 1 mm long; and corroborated with biogeography and phylogenetic relationships.

Accepted species:—

Litanthus pusillus Harv. in London J. Bot. 3: 315, t. 9 (1844) ≡ Drimia uniflora J.C.Manning & Goldblatt in Strelitzia 9: 712 (2000), nom. nov. [non Drimia pusilla Jacq. ex Willd. (1799) ] ( Figs 2.17 , 33.1 ). Type:— SOUTH AFRICA. [Eastern Cape], ‘shady places in the woods by the Zwartkop’s River, Uitenhage, Cape of Good Hope’, [December 1829], Zeyher s.n. (TCD lecto. designated by Jessop in J. S. African Bot. 43: 308. 1977; BOL, SAM!, S barcode S-G-7913! isolecto.).

Litanthus stenocarpus (J.C.Manning & J.M.J.Deacon) Mart. - Azorín, M.B. Crespo, M. Pinter & Wetschnig in Phytotaxa 201(2): 168 (2015) ≡ Drimia stenocarpa J.C.Manning & J.M.J.Deacon in S. African J. Bot. 90: 99 (2013), basionym ( Figs 2.18 , 33.2 ). Type:— SOUTH AFRICA. Western Cape. Vanrhynsdorp (3118): Papendorp , 25 miles W of Vredendal, (–CA), 17 March 1971, H. Hall 3921 (NBG92544! holo.; PRE! iso.).

Figures

FIGURE 2. Seed morphology in Urgineoideae. 1. Drimia neriniformis Baker; 2. Drimia robusta Baker; 3. Fusifilum capitatum (Hook.) Speta; 4. Fusifilum montanum (A.P.Dold & E.Brink) A.P.Dold et al.; 5. Fusifilum physodes (Jacq.) Speta; 6. Geschollia anomala (Baker) Speta; 7. Geschollia brachyandra Mart.-Azorín et al.; 8. Geschollia calcarata (Baker) Mart.-Azorín et al.; 9. Geschollia globuligera Mart.- Azorín et al.; 10. Geschollia occultans (G.Will.) Mart.-Azorín et al.; 11. Geschollia prolifera Mart.-Azorín et al.; 12. Indurgia congesta (Wight) Speta; 13. Indurgia indica (Roxb.) Speta; 14. Iosanthus amboensis (Baker) Mart.-Azorín et al.; 15. Iosanthus macrostigma Mart.-Azorín et al.; 16. Iosanthus toxicarius (C.Archer & R.H.Archer) Mart.-Azorín et al.; 17. Litanthus pusillus Harv.; 18. Litanthus stenocarpus (J.C.Manning & J.M.J.Deacon) Mart.-Azorín et al.; 19. Mucinaea nana (Snijman) M.Pinter et al.; 20. Rhadamanthopsis haworthioides (Baker) Mart.-Azorín et al. All to the same scale in mm.

FIGURE 29. Approximate distribution ranges of accepted genera in Urgineoideae.

FIGURE 33. Species of Litanthus Harv. displayed in horizontal rows of images. 1. Litanthus pusillus Harv.; 2. Litanthus stenocarpus (J.C.Manning & J.M.J.Deacon) Mart.-Azorín et al.