Calydorea minuana Deble & F.S.Alves, 2016

Deble, Leonardo Paz, Alves, Fabiano Da Silva & De Oliveira-Deble, Anabela S., 2016, Calydorea minuana, a new species of Iridaceae from Río de La Plata Grasslands, South America, Phytotaxa 253 (1), pp. 81-89 : 82-86

Calydorea minuana Deble & F.S.Alves , spec. nova ( Figs. 1 , 2 , 3A–C )

Calydorea minuana is closely related to Calydorea nuda ; however, it can be distinguished by its dark-blue or dark violet-blue flowers, basally yellow and without macules, stamens with shorter and white-cream filaments, bigger anthers, style branches free for 2.3–3.5 mm, and by the presence of green leaves at anthesis.

Type:— URUGUAY. Artigas: Arroyo Cuaró Grande , 30º45’19.35”S and 56º45”13.63” W, 16 November 2014, L. P. Deble, A. S. de Oliveira-Deble & F. S. Alves 15681 (holotype SI!; Isotypes CTES! MVFA! MVM! PACA!) .

Plant up to 15–25 cm high above the soil; underground stems 3–8 cm long. Bulb ovoid, 20–30 × 10–15 mm, prolonged in a collar, up to 7 cm long, cataphylls dark-brown, apex acute. Leaves at anthesis 4–10, green, plicate, narrowly linear, 6–17 × 0.04–0.15 cm. Flowering stems 7–19 cm, branching only in flowering spathes. Cauline leaf linearensiform, 2.4–3.6 × 0.05–0.15 cm, base involving the stem. Spathes 1–4, green, herbaceous, bivalved, two-flowered, 20–28 × 2–3 mm, peduncles 1.8–3.1 cm long. Outer valve 12–17 mm long, the inner 19–25 mm long, convolute, both with membranous edges. Pedicel filiform, up to 30 mm long. Flower dark-blue or dark violet-blue, trichomes absent, radially symmetrical, 22–34 mm in diameter. Tepals whorls sharply similar in shape and color, proximally yellowish, after dark violet-blue or dark-blue, spreading; outer tepals oblong or oblanceolate, 14–17 × 6–7 mm, apex slightly acute to obtuse; inner tepals oblong to elliptic, 13–16 × 5–6.5 mm, at apex slightly acute to obtuse. Filaments free, white-cream, filiform and wider at base, 2.6–3.5 mm long; anthers linear, curved at dehiscence, 6–7 mm long; pollen orange. Ovary obovate, 3–4 × 1.7–2.1 mm. Style whitish, 7–8 mm long, style branches 2.3–3.5 mm long; stigma shortly emarginate, yellow. Capsule oblong, 8–11 × 4.5–6 mm. Seeds oblong to obconical, ca. 2 mm long, angled, reddish-brown, epidermis minutely foveolate.

Etymology: —Refers to Minuanos, a group of hunters and gatherers South American pre-historic human group, who inhabited the grasslands north of the Río de La Plata.

Phenology: —Specimens with flowers and capsules can be found between November-December. The flowers open only few hours in one day, in the late afternoon and early evening and wither at night.

Additional specimens examined (paratypes): — BRAZIL. Rio Grande do Sul: Quaraí, Localidade do Jarau, Arroio Garupá, 30º10’25.08” S and 56º27’30.11”W, 6 December 2014, L.P. Deble & F.S. Alves 15682 (SI!). URUGUAY. Rivera: Arroyo Gajo del Lunarejo, “en pradera pedregosa”, 17 November 1995, M. Bonifacino s.n. (MVFA 25054!).

Distribution and habitat: — Calydorea minuana is probably endemic to Artigas and Rivera Departments, northern Uruguay, and neighboring places in southwest Rio Grande do Sul State, Brazil ( Figure 2 ). The specimens occur in elevation range between 100–240 m, growing in streams and small rivers among volcanic rocks belonging to Serra Geral geological formation (see Gordon Júnior 1947, PAULIPETRO 1981, Melfi et al. 1988).

Conservation status: —The new species occurs in less than 10,000 km ² and the area of occupancy is smaller than 10 km 2, moreover only three populations are known, and are composed by few individuals and require highly specific habitats in streams and small rivers among rocks. According to the IUCN Red List assessment protocol ( IUCN 2013) the species can be assigned to the Endangered category (EN, B2a, b(iii), and D), due to the small area of occupancy, few individuals known, specialized habitat, and few places of occurrence.

Comments: — Calydorea minuana is most closely related to Calydorea nuda ( Herbert 1840: t. 3779) Baker (1876: 188), as both species display similar habit, and the flowers open in the late afternoon. However, C. minuana can be distinguished by its dark-blue or dark violet-blue flowers, stamens with shorter and white-cream filaments, bigger anthers, style branches free for 2.3–3.5 mm long, and by the presence of green leaves at anthesis ( Figure 3 ). C. approximata Foster (1945: 46) also flowers in the late afternoon, but this species displays lower habit, almost sessile spathes, and much smaller flowers. In dry material C. minuana superficially resembles C. azurea Klatt (1882: 387) and C. charruana Deble in Deble et al. (2013: 2). However, C. minuana is easily segregated from both species by its small flowers that open in late afternoon (vs. in the morning) and absence of a basal violet or dark violet macula at the base of tepals. Additional features to distinguish C. minuana from its allies are summarized in the Table 1. Other species in the genus, such as Calydorea alba Roitman & Castillo (2005: 311) , Calydorea luteola ( Klatt 1862: 563) Baker (1876: 188) , Calydorea minima Roitman & J.A. Castillo in Deble (2011: 39), and Calydorea riograndensis Deble (2011: 35) show less similarities with C. minuana , although they are here studied and included in the identification key provided below to facilitate identification.

With the description of C. minuana , and following the circumscription of Calydorea accepted by the WCI, the genus now comprises 23 species, and 13 species occur in the RPG, ten of them represented in the sub-region of “Northern Campos”. Except by C. approximata being widespread in central areas of South America, and C. amabilis ( Ravenna 1983: 203) Goldblatt & Heinrich (1991: 511) and C. azurea , both recorded to sedimentary areas between the sub-regions of Mesopotamic Pampa and the Northern Campos, the other 7 species are endemic to the “Northern Campos”, demonstrating the importance of these ecosystems for diversity of the genus Calydorea .

Figures

FIGURE 1. Calydorea minuana. A. Habit. B. Flower and spathe. C. Immature capsule. D. Flower, tepals removed. E. Capsule. F. Seed. G. Apex of style branch and stigma (A–G from L.P. Deble et al. 15681).

FIGURE 2. Geographic distribution of Calydorea minuana.

FIGURE 3. Calydorea minuana. A. Flower, upper view. B. Flower, lateral view. C. Detail of stamens and style. Calydorea nuda. D. Flower, upper view. E. Flower, lateral view. F. Detail of stamens and style (A–C from L.P. Deble et al. 15861; D–F from L.P. Deble et al. 14091).