Hippeastrum euryphyllum (Ravena) W.A. Medina & Roitman, 2023

Florentín, Javier E., Medina, Walter A., Salas, Roberto M. & Roitman, German, 2023, Hippeastrum euryphyllum (Amaryllidaceae), a microendemic species from northeastern Argentina: new combination, description, taxonomic identity and distribution, Phytotaxa 625 (2), pp. 220-226 : 221-224

Hippeastrum euryphyllum (Ravena) W.A. Medina & Roitman , comb. nov. Figs. 1 , 2

Basionym: Amaryllis euryphylla Ravena (2003: 11) . Type: — ARGENTINA. Corrientes, Dpto. San Martín, Tres Cerros , Cerro Capará , 29 January 1976 (fl.), A . Krapovickas & C. L . Cristóbal 29005 (holotype: CTES [ CTES0000200 !]) .

Description:— Perennial herbs up to 83 cm tall. Subterranean bulb among rocks, 48–96 mm diam., brown; neck 18–35 cm long formed by leaf sheaths at the base. Leaves flat, up to 55 cm long during flowering, 3–7 cm wide, glaucous, margins cartilaginous, apex obtuse. Inflorescence 3 flowered; scape cylindrical, 53–60 cm tall; bracts free, 8–8.5 mm long, reddish green in bud, turning papery. Pedicel 36–60 mm long, green. Fragrant perigone, trumpet-shaped, 75–90 × 68–90 mm. Hypanthium tube 9–10 cm long, 7–8.5 mm diam. At ovary, 0.8–1 cm diam. At throat, yellow or light yellow. The inner surface of the tepals present yellowish-white strip at the throat. Sepals obovate, upper 52–54 × 21–24 mm, lateral 50–52 × 16–19 mm, with acute apex; petals narrowly obovate, lateral 60–65 × 21–23 mm, lower 55–57 × 13–18 mm, with acute apex. Staminal filaments 60–65 mm long, bundled, declinate-ascending. Anthers oblong, 6–7 mm long before anthesis, slightly arched, light yellow colored, with yellow pollen. Style declinate-ascending, 14–17 mm long, white with yellowish base; stigma trilobed, lobes open, rounded, 1 mm long, white. Ovary obovate, 10–11 × 3–4 mm, green, with about 40 ovules per locule. Capsule globose-compressed about 21–30 mm long, brown. Seeds flattened half-discoid, about 5–9 mm diam, black.

Phenology: —The species flowers from December to January and fruits from February to March. In cultivation, it flowers from November to January.

Distribution and habitat:— Microendemic species from Paraje Tres Cerros, San Martin, Corrientes ( Argentina). These isolated rocky outcrops are represented by three slopes: Cerro Nazareno, Cerro Capará and Cerro Chico. Hippeastrum euryphyllum grows among rocks on rocky slopes, at elevations ranging from ca 130–164 m and exposed to the sun, surrounded by xerophytic vegetation ( Fig. 3 ).

Taxonomic remarks:— Hippeastrum euryphyllum is distinguished from the other Argentinian species with trumpet-shaped perigone [ H. argentinum ( Pax 1889: 325) Hunz (1967: 13) , H. parodii Hunziker & Cocucci (1959: 5) , H. escoipense Slanis & Huaylla (2022: 488) , and H. vitattum ( L’Héritier 1788: 8) Herbert (1821: 31) ] by its light yellow flowers, very short stylar arms and its very restricted distribution area. The specimen Schinini et al. 17090 (CTES) was provisionally identified as H. elegans ( Sprengel 1815: 59) Moore (1963: 16) , which shares the rounded stigma and general shape of the flowers, however it differs by having the apical 1/3 of the perigone light yellow and 2/3 basal third green (vs. apically milky white to cream and green or yellowish base, sometimes with red-violet) ( Dutilh et al. 2020).

Hippeastrum euryphyllum is commonly confused with H. parodii , however H. euryphyllum is distinguished since it lives in rocky environments (vs. sandy environments), has three flowers per flower stem (vs. four to eight flowers per stem) up to 15 cm long (vs. flowers up to 23 cm long).

Additional specimens examined:— ARGENTINA. Corrientes, Tres Cerros, Cerro Nazareno, 14 February 1979, Schinini et al. 17090 ( CTES, MO); Idem, Tres Cerros, Cerro Capará, 29 January 1976, A . Krapovickas & C . L . Cristobal 29005 ( CTES); Idem, Tres Cerros, Cerro Capará, ladera N , 29°09’14” S, 56°51’45” W, 06 December 2013, W . A . Medina 514 (CTES); Idem, Cerro Capará, ladera N, 29°09’14” S, 56°51’50” W, 06 December 2013, W . A . Medina 525 ( CTES). Tres Cerros, Cerro Chico , cumbre pedregosa, 29°06’46” S, 56°55’12” W, 23 January 2014, W . A . Medina 529 ( CTES); Tres Cerros, Cerro Nazareno , 29°06’37” S, 56°55’55” W, 24 January 2014, W . A . Medina 531 (CTES).

Figures

FIGURE 1. A–H. Hippeastrum euryphyllum (from A. Krapovickas & C.L. Cristóbal 29005). A. Habit; B. Flower in lateral view; C. Flower in frontal view; D. Style and stigma; E. Fruit; F. Immature fruit; G. Seed, frontal view; H. Bulb in vegetative phase. Illustration: L. Simón

FIGURE 2. Hippeastrum euryphyllum. A–B. Habitat; C. Habit; D. Flower in frontal view; E. Flower in lateral view; F. Infructescence; G. Detail of dehiscent fruits and seed. Photos by W. Medina.

FIGURE 3. Distribution map of Hippeastrum euryphyllum. A. Location of the Paraje Tres Cerros, Corrientes province, Argentina; B–D. Details of the hills Nazareno (B), Capará (C), and Chico (D).