Cypella rivularis Chauveau & L.Eggers, 2014

Chauveau, Olivier, Pastori, Tamara, Souza-Chies, Tatiana T. & Eggers, Lilian, 2014, Overlooked diversity in Brazilian Cypella (Iridaceae, Iridoideae): four new taxa from the Río de la Plata grasslands, Phytotaxa 174 (1), pp. 25-42 : 36-40

Cypella rivularis Chauveau & L.Eggers , sp. nov. ( Figs. 8 and 9 )

Cypella rivularis differs strongly from related species by its habitat characterised by small streams running through the pampean grasslands (vs. well drained places for C. laeta and sandy, stony soils for C. suffusa ). Morphologically, it differs from C. laeta by its uniflowered spathes and longer adaxial crests. It is distinguished from C. suffusa by its wider flower diameter, longer outer and inner tepals and longer style arms.

Type: — BRAZIL. Rio Grande do Sul: Uruguaiana , BR 290 , aproximadamente Km 645, campo bem preservado, embaixada, em borda de pequenos riachos, 172 m, 25 November 2013 (fl, fr), L . Eggers et al. 869 (holotype, ICN!; isotypes, MBM!, P!) .

Perennial herb, up to (23.5–)33.5–49(–70) cm high above the soil, underground stem up to (8–)12.5–19(–22) cm long. Bulb obovoid, outer cataphylls dark brown, (28–)32.6–38(–41.4) × (18–) 20.7–27.1 mm, prolonged in a long collar.Basal leaves green at anthesis (2–)4–5(–7), blades linear-attenuate, plicate, (15–)21–51(–59.5) × (0.3–)0.4–0.7(–0.75) cm. Flowering stem cylindrical, (16.8–)26.3–39(–63) cm long, proximally foliate (one reduced cauline leaf, rarely absent), then bracteose; first internode (3–)5.3–13.5(–19.5) cm long; cauline leaf (6.5–)7.2–33.7(–45.7) × 0.2–0.46(–0.6) cm. Synflorescence cymosely branched, branches 2–3(–5), each subtending 2–7 pedunculate inflorescences arising from the same point, peduncles (1.2–)1.9–6(–9) cm long. Inflorescence one-flowered (rhipidium like); spathes herbaceous, bivalved, lower valve (1.3–)1.5–2(–2.2) cm long, the upper (3.2–)3.5–4.7(–7) cm long, both with narrow membranous edges. Pedicel filiform, usually slightly shorter than the upper valve with the ovary partly to entirely exserted, the top of the ovary (3.5–) 6.7–13.6 mm above the top of the upper valve. Flowers predominantly bright yellow, (46–)50– 58(–61) mm diameter. Tepals unequal, shortly fused proximally for (1.2–)1.6–2.1(–2.4) mm. Outer tepals pandurate, 35–39(–42) × (17–)18–22(–25) mm; the proximal part concave, bright yellow, marked with red-brown dots scattered on the whole surface, the distal edge of the concave part devoid of trichomes; the distal part reclinate, bright yellow, obovate, slightly retuse and shortly apiculate. Inner tepals reduced, the proximal two-thirds erecto-patent and lastly curved upward, the distal one-third incurved and abruptly reclinate, 21–24(–25.5) × 9–10.5(–14) mm; the proximal part shortly unguiculate, then distinctly cuneate and slightly constricted lastly, bright yellow, marked with red-brown dots scattered usually on the whole surface; the distal part bright yellow, longitudinally depressed, except at the distal end, with a dense lanceolate yellow area of oil-producing trichomes (elaiophore), the lateral sides firmly revolute, each densely spotted with red-brown, the apex acute. Filaments 6.4–7.8(–9.3) mm long, usually connate basally for (0–)1–2(–3.2) mm, free for (5–)5.6–6.5(–7.5) mm, erect to porrect, whitish-yellow to pale yellow, filiform, 0.2–0.25 mm wide at mid-length, slightly inflated at the base. Anthers narrowly oblong, (7.6–)7.8–8.5(–9) × (1–)1.4–1.7(–2) mm, adnate to the style arms for two-thirds to three-fourths of the length; connective apically excurrent, acuminate, pale yellow, (0.7–)0.9–1.2(–1.4) mm wide, usually covered with a viscous and transparent secretion; locules pale yellow; pollen yellow. Ovary narrowly subclavate, 9–11(–12) × (2.1–)2.4–2.7(–3) mm. Style whitish-yellow to pale yellow, (9.9–)11–15.8(–18) mm long. Style arms pale-yellow, conduplicate, (3.7–)4–4.5(–4.9) mm long; crests at the apex, pale yellow to whitish-yellow; adaxial crest 2, erect, falcate inwards, (5–)5.9–6.8(–7.5) mm long; abaxial crest ovate, obtuse, (1.2–)2.2–3.4(–3.8) mm long; stigmatic surfaces transverse, 2, on each side at the base of the abaxial crest, pale yellow, (0.21–)0.5–1(–1.3) mm long. Capsule obovate-truncate, 18.9–23.1 × 4.8–5.5 mm. Seeds irregularly obovate to conical, sharply angulate, epidermis verrucose, 2.5–4 mm long.

Distribution and Habitat:— Cypella rivularis was collected in the south-western part of the state of Rio Grande do Sul, Southern Brazil ( Fig. 3 ), along banks and in the bed of narrow and stony grassland streams. The elevation records range from 103 to 226 m. The geographical distribution of the species is markedly reduced, but the populations are large and scattered along the small streams. The range of the species falls within the Pampa biome.

Phenology: —Flowering and fruiting from November to December.

Conservation Status: —According to the IUCN Red List guidelines ( IUCN 2001), the species is considered to be Critically Endangered (CR), with subcriteria B2 (a) and (biii): continuing decline of area of occurrence and a decline of quality of habitat. The grassland streams where the species occurs are threatened by land-use changes or environmental degradations of contiguous areas.

Etymology: —Named after the specific grassland habitat of the species, which is not shared by any other member of the genus.

Additional specimens examined (paratypes):— BRAZIL. Rio Grande do Sul: Uruguaiana, estrada secundária para Santana do Livramento a partir da BR 290 , campo bem preservado, em borda de pequeno riacho pedregoso, 211 m, 25 November 2013 (fl), L . Eggers et al. 872 ( ICN!); Alegrete , estrada secundária a partir da BR 290 , aproximadamente Km 611, bulbos entre as pedras em borda de riacho, 103 m, 25 November 2013 (fl), L . Eggers et al. 873 ( ICN!); Alegrete , estrada secundária a partir da BR 290 , aproximadamente Km 620, campo preservado, em borda de pequeno riacho pedregoso, 226 m, 26 November 2013 (fl), L . Eggers et al. 874 ( ICN!) .

Taxonomic relationships: — Cypella rivularis has beautiful big yellow flowers and could be superficially mistaken with C. laeta Ravenna (1981a: 13) and C. suffusa Ravenna (2009: 1) ( Table 4). However, its restricted geographical range and typical habitat are so singular that it can be easily identified. Plants grow in stony soils and between rocks along and in narrow streams of the Pampa grassland. During the flowering time, populations offer dazzling sceneries with dozens of bright yellow flowers scattered along the streams. To date, C. laeta and C. suffusa were not collected in Brazil, but both species occur in the following border provinces of Argentina: Corrientes and Misiones.

Figures

FIGURE 3. Distribution map of Cypella altouruguaya (triangle inside circle), C. hauthalii subsp. minuticristata (star inside circle) and C. rivularis (rhombus inside circle) in Southern Brazil.

FIGURE 8. Habit of Cypella rivularis Chauveau & L.Eggers. From L. Eggers et al. 869 (ICN!), drawing by Anelise Scherer.

FIGURE 9. Cypella rivularis Chauveau & L.Eggers.A–C. Flower.A. apical view B. lateral view C. basal view D–F. Inner tepal D. adaxial view E. abaxial view F. lateral view G. Ovary H. Stamens and style in lateral view I. Style crests and stigmatic replicatures. From L. Eggers et al. 869 (ICN!).