Promenaea viridiflora F.Barros & Barberena, 2015

Barberena, Felipe Fajardo V. A. & Barros, Fábio De, 2015, A new species of Promenaea (Cymbidieae; Epidendroideae; Orchidaceae) from Southeastern Brazil, Phytotaxa 203 (2), pp. 205-209 : 206-209

Promenaea viridiflora F.Barros & Barberena , sp. nov. (Figs. 1,2)

Promenaea stapelioides (Link & Otto) Lindl. similis sed floribus tote viridibus, apice petalorum sepalorumque acuminato, callo labelli erecto, cylindrico vel conico-truncato.

Type: — BRAZIL. São Paulo: Cananéia, Parque Estadual da Ilha do Cardoso, 1988 (fl. cult. Jan 2014), F. Barros s.n. (Holotype SP 465171, barcode SP 002789!).

Epiphytic herbs, 4–8 cm. Rhizomes up to 1.5 cm long. Pseudobulbs 1–1.5 × 0.7–1.3 cm, ovate to suboblong. Leaves 2.5–5 × 1–1.5 cm, oblong-lanceolate, apex acuminate. Inflorescence 1-flowered, 2–4 cm long, bracts 0.7–1 × 0.4–0.6 cm; bracteoles 0.8–1.2 × 0.5–0.7 cm, shorter to longer than the pedicel+ovary; flowers totally pale green, spotless; pedicel+ovary 0.8–1.4 cm, dorsal sepal 2–2.3 × 0.8–1 cm, oblong-lanceolate, apex acuminate, lateral sepals 2–2.1 × 0.9–1.1 cm, oblong to oblong-lanceolate, apex acuminate; petals 2 × 1 cm, obovate, apex acuminate; lip 1.9–2 × 1.5–1.6 cm, outline subcircular, callus not extending over lateral lobes, lateral lobes ca. 0.4 × 0.3 cm, erect, oblong, curved, apex obtuse, median lobe 1.4 × 1.5 cm, subcircular, apex rounded, revolute; lip disk with apex emarginate to 2-toothed, attached to the base on both sides of the two lateral lobes, bearing a transverse crest; callus 0.35 × 0.3 cm, subcylindrical, erect, inserted on the center of the crest, entire at the base and apex; column 0.8–0.9 cm long, entirely green, subcylindrical, column foot ca. 4 mm long; anther ca. 0.35 × 0.25 cm, broadly oblong; the two largest pollinia 2.3–2.4 × 0.8–0.9 mm, oblong-obovate, the two smallest 1.7–1.9 × 0.8 mm, obovate; viscidium 2.5× 1.6 mm, ovatetriangular. Capsule not seen.

Phenology: —Sterile specimens were collected and flowered in cultivation in January 2014.

Etymology: —The specific epithet is related to flower color, main diagnostic feature of the species ( Fig. 2).

Distribution and habitat: —Up to date Promenaea viridiflora is known from collections in only two localities, both in São Paulo state, one in the Parque Estadual da Ilha do Cardoso and the other in Reserva Biológica do Alto da Serra de Paranapiacaba, at elevations ranging from sea level to 820 meters ( Fig. 3 ). Like other species of the genus, P. viridiflora grows in shady and wet habitats in the Atlantic Rain Forest.

Conservation: — Promenaea viridiflora is assessed here as Critically Endangered (CR B2ab [i, ii, iii, v] + C2a[i]) according to the IUCN red list categories and criteria ( IUCN 2014). The species is endemic to the Atlantic Rain Forest and has an area of occurrence (AOO) of 8 km 2. It is restricted to two distinct sites more than 200 km from one another. There are also very few and relatively aggregated adult specimens in each population, certainly fewer than 250 in total and probably fewer than 50 in each subpopulation.

Despite the fact that the species is found within protected conservation units, it is subjected to some threats. Reserva Biológica do Alto da Serra de Paranapiacaba is surrounded by large urban centers. At Parque Estadual da Ilha do Cardoso it receives intense negative impacts from public visitation and land speculation. Such as the other species of the genus, P. viridiflora has specific growth requirements like low luminosity and high humidity. Sites with these favorable ecological characteristics are prone to the effects of stochastic events. Other great concerns are collection pressure since the species has some ornamental value and the fact that it has not been recollected for over 25 years.

Paratype:— BRAZIL. São Paulo: Santo André, Reserva Biológica do Alto da Serra de Paranapiacaba, 23 Jul. 1982 (fl. cult. Jan 2014), F. Barros s.n. (SP465170, barcode SP002790!).

Affinities:—Regarding morphology, Promenaea viridiflora is closely related to Promenaea stapelioides ( Link & Otto 1821: 111) Lindley (1843: 13) by flowers with green background, obovate petals, suborbicular lip outline and lip disk with emarginate to 2-toothed apex, but they differ from each other by the characters presented in the key below and further discussed. The specimens of P. stapelioides always present green sepals and petals with purple riflings with a mainly purplish-black lip. The flowers of P. viridiflora are entirely pale green, without any stain. The measures and shapes of the floral structures of both species are similar, but the sepals and petals of P. viridiflora have an acuminate apex, and the callus of the lip is erect, with cylindrical to truncated cone shape. The sepals of the P. stapelioides have acute to obtuse apex and the petals have obtuse to rounded apex, and the callus is more or less flattened, lying on the disk. Despite being morphologically close to P. stapelioides , phylogenetic studies on the genus ( Barberena 2014) highlighted that P. viridiflora is closer to P. xanthina ( Lindley 1839: sub. t. 17) Lindley (1843: 13) than to P. stapelioides , with strong bootstrap support. However, unlike P. viridiflora , P. xanthina has yellow flowers (rarely white) with some stripes and spots in the lip, and the callus is sub-erect and curved backwards.

A key to differentiate these three species is presented below.

1. Flowers with yellow (rarely white colored) background; lip disk with 3(–5)-toothed .................................... Promenaea xanthina

1’. Flowers with green background; lip disk with apex emarginate to 2-toothed.

2. Lip callus more or less flattened and lying on the disc; sepals and petals green with purple riflings, with apex acute, obtuse or rounded; lip mainly purplish-black ...................................................................................................... Promenaea stapelioides

2’. Lip callus erect with cylindrical to truncated cone shape; sepals and petals entirely pale green, with apex acuminate; lip entirely pale green ................................................................................................................................... Promenaea viridiflora

Figures

FIGURE 3. Distribution map of Promenaea viridiflora (black triangles).