Sisyrinchium pampeanum C.D.Inácio & L.Eggers, 2018

Inácio, Camila Dellanhese, Chauveau, Olivier & Eggers, Lilian, 2018, Three new species of Sisyrinchium (Iridaceae) from Campos of South America, Phytotaxa 361 (2), pp. 198-210 : 198-202

Sisyrinchium pampeanum C.D.Inácio & L.Eggers , sp. nov. ( Figs. 1A and 2 )

Sisyrinchium pampeanum resembles S. scariosum , but differs by its cup-shaped perigone and conical staminal column, basally with elaiophores for 1.1–1.5 mm long.

Type: — BRAZIL. Rio Grande do Sul: Santana do Livramento, parte baixa do Morro Tabatinga, na borda da mata, 213 m, 30°52’36.7’’S, 55°8’44.7’’W, 7 November 2013, C.D. Inácio et al. 147 (holotype ICN!, isotypes MBM!, SI!, MVM!).

Perennial herb, erect, (11–) 27.5–57 cm tall. Rhizome inconspicuous, with slender and fibrous roots. Basal leaves, erect, terete, (6–)12–50 × 0.05–0.11 cm, glabrous, acute. Flowering stem simple, erect, terete, 5–48 × 0.05–0.15 cm, with a terminal bract (1–)4–15(–20) cm long, proximally membranaceous for 1.5–2 mm. Synflorescence fasciculiform, (1–)3–10(–14) rhipidia, congested between the base of the terminal bract and an opposite bract, 8.2–13.1(–18.1) mm long, cuspidate to aristate, awn 1–8.6 mm long, margin conspicuously membranaceous for 0.9–2.3 mm wide. Rhipidium 2–5 flowers, subsessile, peduncle 1–4 mm long, sometimes subtended by a sterile bract with membranaceous margin and scabrous keel. Spathes bivalved, lower valve 9.3–10.3(–13.9) × 1.5–2.6 mm, upper (8.1–)10.8–15.6 × 1.5–2.5(– 3.2) mm, acute to cuspidate, margin membranous for 1–1.5 mm. Pedicel longer than spathes, 10–18 mm long, with light yellow straight capitate trichomes, 0.5 mm long. Perigone cup shaped, flaring distally; mostly white, internally yellow to chestnut, fauces brown to vinaceous, 12–16 mm diameter (fresh flowers). Tepals subequal, 6.7–9.9 × (2.4–) 3.3–4 mm, connate 0.5 mm at base, oblanceolate, emarginate-apiculate, with three dark veins and sparse trichomes at both sides and margin. Filaments light yellow or inconspicuously vinaceous, connate. Staminal column, 2.3–2.6 mm long, basally conical, with oil-producing trichomes (elaiophores) for 1.1–1.5 mm, then with sparse trichomes. Anthers yellow, basifixed, 0.4-0.6 mm long. Ovary globose, 1.2–1.9 mm long and wide, pubescent, with light yellow straight capitate trichomes. Style yellow, entire, 3.2–3.6 mm long, with stigmatic region displaced above the anthers. Capsule globose to subglobose, 3.5–4.8 × 3.5–5.3 mm, brown, pilose.

Distribution and Habitat:— Sisyrinchium pampeanum is known from the Western region of Rio Grande do Sul, Brazil ( Fig. 3 ), at Santana do Livramento and Quaraí municipalities, and from North of Uruguay, Artigas province. Plants occur in forest edges and in grassland matrix, in small tussocks, being frequent at the collection sites. The elevation records range from 150 to 439 m a.s.l. The species distribution is restricted to the Pampa Biome.

Phenology:—Flowering and fruiting from October to November.

Conservation Status: —According to the IUCN Red List guidelines ( IUCN 2016), the species is considered Endangered (EN), with subcriteria B1(a) and (b)iii: continuing decline of extent of occurrence and a decline of quality of habitat due to loss or reduction of the natural distribution by agricultural expansion of crops and cattle raisin. The species is not reported for conservation units of the region.

Etymology:—The species is named in reference to its distinctive geographical distribution in the Pampa Biome.

Paratypes: — BRAZIL. Rio Grande do Sul: Santana do Livramento, Morro Tabatinga , 16 October 2009 (fl), L. Eggers & T. T. Souza-Chies 497 ( ICN!) ; Santana do Livramento , estrada secundária a partir da BR 293, 288 m, 30°45’9.1’’S e 55°39’31.0’’W, 4 November 2010 (fl), E. M. Stiehl-Alves & L. Dal Ri 7 ( ICN!) ; Santana do Livramento, Fazenda Santo Antônio, divisa com Uruguai , 9 November 2009 (fl, fr), I. Boldrini, R. Trevisan & R. Setubal 1604 ( ICN!) ; Quaraí, RS 377, Cerro do Jarau , 151 m, 30°11’43.56”S, 56°29’19.32”W, 17 October 2009 (fl), L. Eggers & T. T. Souza-Chies 515 ( ICN!) ; Quaraí , S30 17.542, W55 58.684, 1 November 2010 (fl, fr), P. J. Silva Filho & M. Grings 1031 ( ICN!) ; Quaraí, Cerro do Jarau , 28 October 2011 (fl, fr), Aita 89 ( ICN!) . URUGUAY. Artigas: Cuaro, Ruta 4, approximately Km 170, 439 m, 30°37’50.9’’S, 56°39’48.4’’W, 8 November 2013 (fl, fr), C. D. Inácio et al. 151 ( ICN!, MVM!) .

Taxonomic relationships: — Sisyrinchium pampeanum belongs to S. sect. Cephalanthum Baker (sensu Inácio et al. 2017), characterized by taxa with fasciculiform synflorescences, filaments connate nearly to the top and usually with dense trichomes (elaiophores) (occasionally, moderate at the base of the staminal column). The species presents terete leaves and flowering stems, differing from related taxa by the very distinctive cup-shaped perigone. Sisyrinchium scariosum Johnston (1938: 386) is morphologically the most similar species, differing by the spreading tepals and the cylindrical staminal column, compared to the conical staminal column of S. pampeanum . Both species present similar or even sobreposition of measurements of plant height, leaf length and width, floriferous stem length and width, flower number per rhipidium, pedicel length, flower diameter, anther length and ovary length and width ( Table 1). However, length of the lower and upper valves of the spathes, extension of fused tepals, flower color and elaiophore extension are important features to distinguish the taxa ( Table 1). The cup-shaped flower and the color of tepals may resemble some variations of S. pachyrhizum Baker (1876: 269) , but the fleshy roots and flat leaves of this last species are distinctive.

Figures

FIGURE 1. Habit. A. Sisyrinchium pampeanum C.D.Inácio & L.Eggers. From C.D. Inácio et al. 147 (ICN). B. Sisyrinchium sectiandrum C.D.Inácio & L.Eggers. From G. Hatschbach 27163 (MBM). Scale bars: 5 cm. Drawings by Anelise Scherer.

FIGURE 2. Sisyrinchium pampeanum C.D.Inácio & L.Eggers. A. Flowers in frontal view. B. Flower in lateral view with two removed tepals, showing androgynoecium. C. Synflorescence. D. Habitat in Campos vegetation, Uruguay. From A to C: C.D. Inácio et al. 147 (ICN), D: C.D. Inácio et al. 151 (ICN).

FIGURE 3. Distribution map of Sisyrinchium pampeanum (squares), S. diversicarpum (circles) and S. sectiandrum (triangles) in Southern Brazil and Uruguay border.