Iosanthus macrostigma Mart.

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 : 59-61

Iosanthus macrostigma Mart. -Azorín, M.Pinter, M.B.Crespo & M.Á.Alonso sp. nov.

( Figs 30.2 , 31 ).

Type:— NAMIBIA. Windhoek , Klein Windhoek, elev. ca. 1600 m, ex hort 08 May 2015, I. Pehlemann s.n. (WIND holo.; ABH iso.) .

Diagnosis:— Planta speciosa ceteris speciebus Iosanthi valde affinis, sed eis distinctissima filamentis staminum ad tertium inferiorem tepalorum adnatis, et stigmatibus notabilis valde incrasato-capitatis, trilobatis et glandulosis.

Description:—Bulbous geophyte to 4 cm high. Bulb hypogeal, usually solitary or growing in small groups, ovoid to subglobose and depressed in old plants, 1.5–3.0 × 1.0– 2.5 cm, extended into a 1–2 cm long hypogeal neck; outer tunics pale brownish, membranous. Roots thickened and branched. Leaves 4–11 per bulb, narrowly linear, suberect, canaliculate, somewhat twisted, 2–10 × 0.10–0.18 cm, glabrous, green, with distinct dark maculae at base, withered at flowering time. Inflorescence a short raceme with 3–5 flowers, opening one by one in consecutive days; peduncle erect, pale grey, 15–20 mm long, with small protuberances near raceme, specially in fruit; pedicels 4–5 mm long at anthesis, slightly elongating to 7 mm in fruit, with small protuberances near flower; bracts small, deltoid, 1.0– 1.2 mm long, green with translucent membranous margins, with short spur ca. 0.6 mm long. Bracteoles absent. Flowers stellate, patent to suberect, vespertine-nocturnal. Tepals 6, biseriate, free or only shortly connate at base, narrowly lanceolate-oblong, with somewhat cucullate apex, whitish to carneous colour with central longitudinal brownish-green longitudinal stripe evident on both sides, connivent along basal half to form slightly urceolate tube and spreading to patent above; outer tepals oblong and widened in apical portion, 8–9 × ca. 2 mm; inner tepals narrowly obovate, tapering to base, 8–9 × ca. 1.5 mm. Stamens 6; filaments white, subterete, adnate to tepals for ca. 2 mm, free portion ca. 5 × 0.4 mm, connivent to style and slightly spreading above perigone; anthers yellow, ovate, ca. 1 mm long after dehiscence, dehiscing longitudinally along their whole length, with yellow pollen. Ovary green, ovoid, 3-locular, ca. 3 × 1.8 mm, attenuate to style. Style white, elongated, erect, ca. 5 mm long, slightly thickened and clavate. Stigma ca. 1 × 2 mm, distinctly thickened, dome-like, trilobate, with widened lobes reflexed and papillose. Capsule trilocular, loculicidal, ovoid to subglobose, 7–9 × 7–9 mm, suberect, with remains of perigone circumscissile below and forming an apical cap, valves ovate, apiculate, splitting to base and widely spreading to expose seeds. Seeds black, heart shapped, 8–9 × 6–7 mm, flattened with prominent embryo, broadly winged, emarginate hilum, with sinuous anticlinal testa cell walls.

Etymology:—Named after the distinctly thickened, dome-like, trilobate stigma.

Phenology:— Iosanthus macrostigma flowers from March to May in cultivation in Alicante ( Spain) and fruit and seeds are set from May to June. Flowers open in the evening at about 18h00 and last for a night, a behaviour also shared with the sister species I. amboensis . Further studies are necessary to elucidate the biology of this remarkable species in the wild.

Habitat and distribution:—The species is only known from the surrounds of Klein Windhoek, Windhoek, Namibia (I. Brase, formerly I. Pehlemann, pers. comm.) where it occurs in highland shrubland. The locality is about 1600 m elevation, supports a mean annual rainfall of 530 mm and a mean annual temperature of 18.5ºC. We were not able to confirm the presence of this species in that region, and the material and information used for the description of the species was provided without detailed locality details. Further studies are needed to confirm the distribution and habitat of this species.

Diagnostic characters and taxonomic relationships:— Iosanthus macrostigma is characterised by the solid hypogeal bulb; the 4–11 proteranthous, filiform, canaliculate, glabrous, leaves, which are maculate at the base; the lax, pauciflorous raceme; the vespertine-nocturnal flowers with free tepals, which are connivent along the basal half and spreading apically, and the adnate filaments; the erect, elongate, subclavate style supporting a distinctly thickened, dome-like, trilobate, papillose stigma, the capsules with the withered tepals atop and widely spreading valves; and the heart-shaped, flattened, winged seeds with prominent embryo ( Figs 2.15 , 30.2 , 31 ). The new species is well characterized in having a very swollen stigma, reminiscent of some Thuranthos species. It shares the typical capsules and seeds of I. toxicarius and I. khubusensis , a link supported by phylogenetic studies ( Martínez-Azorín et al. 2023a), despite the differences in flower morphology, which could be linked to different pollination syndromes. Our recent unpublished phylogenetic work places this species as sister to I. amboense , with strong support—a result supported by their shared vespertine-nocturnal flowers, filaments long adnate to tepals, and the maculate, twisted leaves.

Iosanthus toxicarius (C.Archer & R.H.Archer) Mart. -Azorín, M.B.Crespo, M.Pinter, Slade & Wetschnig in Pl. Biosyst. 153(4): 586 (2019) ≡ Ornithogalum toxicarium C.Archer & R.H.Archer in S. African J. Bot. 65(5–6): 431 (1999), basionym ≡ Drimia toxicaria (C.Archer & R.H.Archer) J.C.Manning & Goldblatt in Bothalia 49(1): 3 (2019) ( Figs 2.16 , 32 ). Type:— SOUTH AFRICA. Western Cape. Beaufort West (3222): farm Ryst Kuil 351, in vicinity of old uranium mine, (–DB), 08 October 1983, Retief & C. Reid 239 (PRE0656451! lecto. designated by Martínez-Azorín et al. 2019c: only the bulb with withered leaves and two inflorescences placed on the lower part of the sheet). Note:—The lectotype of this name was first designated in a paper effectively published online 18 December 2018 by Martínez-Azorín et al. (2019c). Subsequent superfluous lectotypification published on 10 April 2019 by Manning (2019) is fully coincident with our previous type selection.

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 30. Species of Iosanthus Mart.-Azorín et al. displayed in horizontal rows of images. 1. Iosanthus amboensis (Baker) Mart.- Azorín et al. (top 3 rows of images) (Photographs by A. Eichhoff); 2. Iosanthus macrostigma Mart.-Azorín et al.

FIGURE 31. Iosanthus macrostigma Mart.-Azorín et al. from Klein Windhoek, Namibia (Type locality). a. Portion of bulb and inflorescence; b. Inflorescence; c. Flower in frontal view; d. Dissected tepals with stamens; e. Tepals with adnate stamens; f. Gynoecia; g. Dissected flower in lateral view; h. Developing capsules; j. Capsules and seeds; k. Seed; m. Leaves. Scales 5 mm.

FIGURE 32. Iosanthus toxicarius (C.Archer & R.H.Archer) Mart.-Azorín et al.