Sobralia fugax Baranow & Dudek, 2018

Baranow, Przemyslaw & Dudek, Magdalena, 2018, Sobralia fugax (Orchidaceae: Sobraliae) - a new species from Colombia described on the basis of morphological study and phylogenetic analyses, Phytotaxa 372 (4), pp. 273-282 : 276-278

Sobralia fugax Baranow & Dudek sp. nov. ( Figures 1 & 2 ).

Type:— COLOMBIA. Valle del Cauca, Feb 2011, Niessen cult. sub Szlachetko s.n. (holotype UGDA!, isotype UGDA —spirit collection!)

Different from other species of Sobralia section Sobralia by the greenish, fleshy sepals and strongly bent ovary which determines the orientation of the flower making it hanged down in contrast to other species of the group which produce flowers directed forward. Additionally that sepals and petals of the new species are not reflexed making the flower appearance distinctly more slender.

Etymology:— From the Latin fugax (ashamed). Named in an allusion to the barely open and hanged down flowers of the species what makes the plant looking “ashamed”.

Terrestrial plant 80–125 cm tall, growing in clumps of few stems which are erect, covered by sheaths in basal two thirds and leafy above. Leaves 3–5 on each stem, 10–16 × 4–6 cm, obovate, long acuminate, tridentate at the apex, leathery, glabrous, plicate. Inflorescence subtended by foliaceous bracts, covered with two narrowly, dark-brown, triangular, acute bracts, producing single flower at a time. Ovary 50–60 mm long, white basally, becoming greenish towards the flower, strongly recurvate in the apical half what makes the flower directed downwards. Sepals apically retrose outwards, basally connate for about 10 mm, distinctly thicker than the petals and lip, light green, darker on the outer surface than on the inner one. Dorsal sepal 75 × 18 mm, oblanceolate, acute, mucronate. Lateral sepals 75 × 18 mm, oblanceolate, acute, mucronate. Petals 68 × 24 mm, widely oblanceolate, rounded, with somewhat curled and irregular margins in the apical half, white. Lip 71 × 50 mm, obovate when spread, bilobed apically, basal half forming a tube in natural position, margins of apical half spread and strongly curled and irregular, apically bilobed, white outside, the inner surface bright yellow except the inconspicuous thickenings running along the central nerves and the spreading apical part of the lip. Lip margins entire or irregular. Column 43 mm tall, club-shaped, with oblong, acute lateral stelidia not exceeding the anther cup.

General distribution:— Known only from the type locality.

Notes:— The phylogenetic trees obtained placed the newly described species among other representatives of Sobralia section Sobralia . The structure of the inflorescence which is the basis of the infrageneric classification proposed by Brieger (1983) confirms the results. Thus, we treat the new species into the nominal section of the genus.

According to the phylogenetic results, the new species is related to S. cobanensis Archila (1999: 14) , S. ecuadorana Dodson (1998: 22) , S. fimbriata Poeppig & Endlicher (1836: 54) , S. powellii Schlechter (1922: 11) , S. tricolor Dressler (2005: 941) , S. warscewiczii Reichenbach (1852: 714) , S. withneri Bennett & Christenson (2001: 764) and S. virginalis Peeters & Cogniaux (1899: 3) but none of the taxa resemble Sobralia fugax .

Sobralia cobanensis differs in larger leaves (20 × 9 cm versus 10–16 × 4–6 cm), wider (30 mm versus 24 mm) and distinctly stronger crenate petals which are always recurved backwards and distinctly shorter column (30 mm versus 43 mm). Apart of that, the flowers of Sobralia cobanensis are purple and white.

The characteristic features of Sobralia ecuadoreana are the thin, leathery leaves, the short floral bracts barely exceeding the sheath subtending the leaf-like bract, the long fleshy lamellae on the basal part of lip reaching third of its length and the distinctly shorter column than the one observed in new species (30 mm versus 43 mm). While the lip color of S. ecuadorana is similar with S. fugax , its sepals are white or pinkish.

The distinctness among the new species and Sobralia fimbriata , S. tricolor and S. withneri is evident from the first glance. All the three species have lips furnished with fimbriate lamellae and the margin of the lip is fimbriated.

Sobralia powellii also can be distinguished from the new entity by the larger leaves (up to 22 × 6 cm), larger flowers (floral segments up to 85 mm long) and wider petals (ca. 30 mm). The species also differs on the color of its flowers which are white with yellow lip throat and disc.

Sobralia warszewiczii has purple flowers with deeply erose margins of apical half of lip. According to the original drawings of the type material, its lip has no protuberances on its surface except the basal papillae.

Sobralia virginalis is a species with white flowers with orange base and disc of lip ornamented with white lines running along the nerves. Additionally, its lip margin is deeply dentate in apical part.

Taking into account that not all the species are included in the molecular study, it is possible that the plant described as a new species represents one of the already known taxa. However, the comparison of its morphology with all other Colombian species of the section based on our recent study ( Baranow et al. 2014, Baranow 2015) allowed us to exclude such possibility.

Sobralia fugax is unique by the greenish, fleshy sepals and strongly bent ovary which determines the orientation of the flower. It is hanged down in contrast to other species of the group which produce flowers directed forward. It is also worthy to mention, that sepals and petals of the new species are not bent backwards what makes its flowers distinctly more slender. The mentioned observations were made on the basis of three flowering periods thus we can assume that these are constant features of the plant.

Figures

FIGURE 1. Sobralia fugax Baranow & Dudek:A. Habit. B. Apical part of stem with the inflorescence. C. Dorsal sepal. D. Lateral sepal. E. Petal. F. Lip. Natural position. G. Lip, spread (drawn from the holotype).

FIGURE 2. Sobralia fugax Baranow & Dudek: A. Flower, side view. B. Dorsal sepal. C. Lateral sepal. D. Petal. E. Lip. F. Interior surface of lip. G. Column (photographs taken from the holotype)