Schomburkgia vandenbergiana E.Pessoa, V.Brito, & F.Ralf-Neto, 2022

Pessoa, Edlley M., Brito, Vinícius, Ralf-Neto, Fraterno, Fernandes, Geysla, Gomes, Gustavo, Fraga, Elmary & Barros, Maria Claudene, 2022, Description and phylogenetic relationships of a new, purple-flowered, endangered Schomburgkia (Laeliinae; Orchidaceae) from north-eastern Brazil, Phytotaxa 561 (2), pp. 151-161 : 156-157

Schomburkgia vandenbergiana E.Pessoa, V.Brito, & F.Ralf-Neto , sp. nov. ( Fig. 4 )

Type: — BRAZIL. Alagoas: Quebrangulo, Serra da Mandioca , 475 m elev., 10 Nov 2019 (fl.), Brito & Ralf-Neto 33 (holotype: MAC; isotype: RB) .

The new species is similar to S. heidii but differs in its shorter sepals (1.8–2.3 vs. 2.6–2.8 cm) and lip (1.5–1.6 vs. 1.7–1.8 cm) and an erose clinandrium margin (vs. entire).

Description: —Epiphytic or saxicolous herbs. Pseudobulbs clavate, 13.5−17.5 × 1.5−2.3 cm, green, distally wider, 4 internodes. Leaves 2, apical, elliptic to oblong-elliptic, 20.0−21.0 × 2.0− 4.5 cm. Raceme 53.1−64.5 cm long; peduncle 49−60 cm long, peduncle bracts 5.0− 6.5 cm long, close fitting, acute at apex; rachis 4.1−4.5 cm long, floral bracts 3.0−5.0 cm long, lanceolate, acute apically. Flowers resupinate, 7–10 per inflorescence; ovary 3.5−6.0 cm long, pink or pinkish green, smooth; dorsal and lateral sepals equal, 1.8−2.3 × 0.6−0.7 cm, dark purple, ellipticlanceolate, slightly concave, glabrous, margin entire, strongly undulate, obtuse to round at apex; petals 1.7−2.0 × 0.5−0.6 cm, dark purple, lanceolate, glabrous, margin entire, strongly undulate, obtuse to round at apex; lip 1.5−1.6 × 0.5−0.7 cm, trilobed, pink, glabrous; lateral lobes 0.8−0.9 × 0.3−0.4 cm, elliptical, obtuse at apex, margin entire, mid lobe 0.65−0.80 × 0.60−0.70 cm, sub-orbicular, strongly inflexed, sessile, margin entire, round at apex; three major and two minor longitudinal keels on the disk, keels undulate, pale pink; column 1.0−1.4 × 0.55−0.6 cm, sub-clavate, free, adaxially pink, abaxially white with pink dots, slightly curved, ventral margins prominent, concave, clinandrium trilobed, margin erose, stigma ovate, rostellum ovate; anther cap ovate, ca. 0.2 cm long, yellow, pollinia 8, ovate, laterally compressed. Capsules not seen.

Additional specimen examined:— BRAZIL. Pernambuco: Agrestina-Altinho, Serra do Gado Bravo , 850 m elev., 18 Nov 2010 (fl.), Sobral-Leite & Gomes 1203 ( UFP, BHZB, HUEFS) .

Distribution and phenology: —Known from Pernambuco and Alagoas in north-eastern Brazil ( Figure 5 ). The population in Pernambuco is saxicolous (ca. 700 m elev.), growing about 60 km from the coast. The local environment is dry, and the surrounding vegetation is Caatinga ( Pessoa et al. 2014). The population in Alagoas occurs at two sites in Serra da Mandioca (ca. 500 m elev.). The specimens are epiphytes, and the vegetation is seasonally dry Atlantic Forest ( Nusbaumer et al. 2015; Fig. 6 ). The specimens we observed in the field and in cultivation flower in November.

Etymology:— Honouring Cássio van den Berg, a Brazilian botanist who has dedicated his career to the study of orchids, especially Laeliinae .

Conservation status:— None of the three known populations is within protected areas. Their extent of occurrence is 115.836 km ² and area of occurrence is 12.000 km ², indicating the new species should be classified as endangered based on the IUCN (2017) criteria B1ab(i)+2ab(ii). The areas where the populations occur suffer from severe anthropogenic disturbance, with the most important threats being cattle grazing and poachers who have been selling plants of this species for years.

Notes:— Schomburgkia undulata and S. elata have longer sepals (3.3–3.5 cm long vs. 2.0 cm in S. vandenbergiana ) and also differ in the number of keels on the disc of the lip: S. undulata has five major and two minor keels, S. elata has only three major keels and S. vandenbergiana has three major and two minor keels. Schomburgkia heidii has smaller flowers and also three major and two minor keels on the disc but differs from the new species by the entire margin of the clinandrium (vs. erose). Only S. gloriosa is known to occur in the Atlantic Forest of Brazil to date, and it is easily distinguished from S. vandenbergiana by the flower colour (dark purple vs. pale brown). Overall, the new species has the smallest flowers of the genus ( Table 2 ).

Figures

FIGURE 4. Schomburgkia vandenbergiana. A. Habit (scale bar = 2.0 cm). B. Inflorescence (scale bar = 1.0 cm). C. Flower in natural position (scale bar = 1.0 cm). D. Dissected perianth (scale bar = 1.0 cm). Photos of the specimen collected as type by V. Brito.

FIGURE 5. Map with the known localities of S. vandenbergiana populations in north-eastern Brazil. Brazilian states of Alagoas and Pernambuco in grey.

FIGURE 6. A. Habitat of S. vandenbergiana at the type locality, Serra da Mandioca, Alagoas, Brazil. B. Phorophyte with specimens of S. vandenbergiana. C. A specimen in the natural habitat. Photographs by V. Brito.