Vanilla rupicola Pansarin & E.L.F.Menezes, 2023

Pansarin, Emerson Ricardo & Menezes, Euler da Luz Fernandes, 2023, A new remarkable Vanilla Mill. (Orchidaceae) species endemic to the Espinhaco Range, Brazil: its phylogenetic position and evolutionary relationships among Neotropical congeners, PhytoKeys 227, pp. 151-165 : 151

Vanilla rupicola Pansarin & E.L.F.Menezes sp. nov.

Figs 1 , 2

Type.

Brazil. Minas Gerais: Mun. Diamantina, Distrito de Sopa, Afloramento rochoso ca. 2 km de Morrinhos, 18°11'43"S, 43°43'18"W, 817 m, 29 November 2022, E.R. Pansarin & E.L.F. Menezes 1561 (holotype: SPFR18105!) .

Vanilla rupicola differs from all Neotropical Vanilla species by its rupicolous habit, its reptant stem and its rounded leaves. The overall characteristics of V. rupicola resemble those of V. appendiculata Rolfe and V. hartii Rolfe. However, the remarkable new taxon ( V. rupicola ) is easily distinguishable from both related species by its leaves and flowers, which are smaller than those of V. appendiculata and larger than those of V. hartii (Table 1 ), its sessile leaves (vs. petiolate in V. appendiculata and V. hartii ), and its papillose labellar protrusions (vs. finger-like in V. appendiculata and verrucose in V. hartii ).

Description.

Rupicolous herbs up to 12 m in length. Roots axillary, 1.8-2.2 mm diam., yellowish-green, one per node. Stem reptant, flexuous, cylindrical, fleshy, glabrous, green to yellowish-green; internodes 40-130 × 3-13 mm. Leaves 3.2-9 × 2.8-5.2 cm, alternate, ovate to rounded, fleshy, glabrous, green to yellowish-green, apex acute to acuminate, sessile. Inflorescence 4.5-6 cm long, apical or axillary, racemose, with up to 10 flowers opening in succession; one flower opening each morning; bracts 5-9 × 3.5-7 mm progressively smaller toward the apex, alternate, triangular to ovate, coriaceous, adpressed to patent, concave, apex acute to acuminate. Flowers resupinate, whitish-green, pedicellate, abscission layer between perianth and ovary present; pedicel with ovary 2.8-3.2 × 0.40-0.52 cm, green, incurved, dilated to the apex, triangular in transverse section. Sepals 5.8-6.3 × 1-1.3 cm, free, oblanceolate, fleshy, slightly concave, pale green, margin entire, slightly incurved, apex acute to obtuse; dorsal sepal symmetric; lateral sepals asymmetric. Petals 5.7-6.2 × 0.7-1.2 cm, free, linear to slightly spatulate, asymmetric, membranous, pale green, apex acute to acuminate, adaxial surface with a longitudinal rib. Labellum 3-lobed, 5.6-6.3 × 3.2-3.5 cm, white, inner surface with longitudinal brown stripes, with a prominent central crest near the apex, and with a penicillate callus just below the anther; central crest ca. 4-5 mm wide, with yellow or white papillose protrusions arranged in five longitudinal lines near the apex; penicillate callus 5-6 × 5.2 mm, white; margins fused from the base to ca. ¾ of the column length forming a tubular nectar chamber; nectary chamber 2.2-2.6 cm in length; lateral lobes rounded, overlapping above the column, undulate margins; apical lobe rounded to emarginated, reflexed, undulate to slightly fimbriate. Column 4.2-4.8 × 0.3-0.4 cm, semi-cylindrical, slender, sinuous, white, attenuate base, dilated to the apex, with white-hyaline hairs close to the stigma, apex ending in a membranous ochrea; anther 4.9-5.1 × 3.9-4.2 mm, white, versatile; rostellum 3.8-4.1 × 3.9-4.0 mm, rectangular to trapezoidal, white. Fruits 9-13 × 1-1.8 cm, linear, tapering towards the apex, triangular in transverse section, green when immature. Seeds ovate, black.

Distribution and ecology.

The species has been reported for the campos rupestres vegetation of the Espinhaço Range of Minas Gerais (ERMG), municipality of Diamantina, Southeastern Brazil. In this locality, Vanilla rupicola shows a reptant habit on rock outcrops and rooting in rock clefts. The elevation is from 800 to 1300 m a.s.l. The flowers produce a sweet fragrance perceptible during the hottest hours of the day. Each flower lasts ca. 12 hours.

Phenology.

Vanilla rupicola has been collected with flowers from late September to early November. The fruits ripen from May to June.

Etymology.

The specific epithet ( Vanilla rupicola ) refers to the rupicolous habit, uncommon among Neotropical Vanilla .

Conservation status.

Vanilla rupicola is a rare species currently known to grow in a mountain-chain of Diamantina, in the ERMG. The populations found are composed of few specimens. According to the IUCN red list categories and criteria and guidelines, the species can tentatively be considered as Endangered (EN) due to its geographic range which is estimated to consist of 30 km2, and fewer than 250 individuals were recorded in the occurrence area.

Additional specimens examined (paratypes).

Brazil. Minas Gerais: Mun. Diamantina, Parque Nacional das Sempre Vivas, Próximo a Serra do Landim, 17°53'27,6"S, 43°45'51.3"W, 1293 m elev., 22 October 2019, E.L.F. Menezes 133 (DIAM!). Municipio de Sopa. Estrada vicinal, 18°11'33.2"S, 43°47'07.5"W, 1210 m alt., 19 November 2022, E.L.F. Menezes 752 (HDJF!); Distrito de Sopa , Afloramento rochoso ca. 2 km de Morrinhos, 18°11'43"S, 43°43'18"W, 817 m, 29 November 2022, E.R. Pansarin & E.L.F. Menezes 1562 (BHCB!); Distrito de Sopa , Afloramento rochoso ca. 2 km de Morrinhos, 18°11'43"S, 43°43'18"W, 817 m, 29 November 2022, E.R. Pansarin & E.L.F. Menezes 1563 (UEC!); Distrito de Sopa , Afloramento rochoso ca. 2 km de Morrinhos, 18°11'43"S, 43°43'18"W, 817 m, 29 November 2022, E.R. Pansarin & E.L.F. Menezes 1564 (SP!); Distrito de Sopa , Afloramento rochoso ca. 2 km de Morrinhos, 18°11'43"S, 43°43'18"W, 817 m, 29 November 2022, E.R. Pansarin & E.L.F. Menezes 1565 (LBMBP!) .

Morphological affinities.

Vanilla rupicola is easily recognized by its uncommon rupicolous habit, by its reptant stems, and by its sessile and rounded leaves. These characteristics differ significantly from those of the remaining non-membranaceous Vanilla species, which are characterized by their hemiepiphytic or more rarely epiphytic habit and by their elliptic to lanceolate leaves. Floral features suggest a close relationship between V. rupicola and some species currently recognized in the V. planifolia group and V. trigonocarpa group mainly regarding the type of appendages of the central crest of the labellum, and labellar color pattern, with longitudinal brown lines over a white background that converge at the entrance of the nectary. In addition, species of the V. planifolia group show a white penicillate callus just below the gynostemium apex. Among the members currently recognized in the V. planifolia group, our data suggest taxonomic affinities between V. rupicola and the Amazonian V. appendiculata. In fact, both species share characteristics that are uncommon among Neotropical Vanilla , such as the production of apical inflorescences and ovate to obovoid leaf blades. The inflorescences of members of the V. planifolia group are lateral, and their leaves are elliptical to lanceolate. In addition, V. rupicola also shares some floral features with the Amazonian V. hartii (currently included in the V. trigonocarpa group), such as the lip lobes with undulate margins, labellar protrusions arranged on five longitudinal lines near the apex, and brown lines converging at the nectar chamber. The main differences between V. rupicola and related species ( V. appendiculata and V. hartii ) are summarized in Table 1 .

Figures

Figure 1. Habit of Vanilla rupicola Pansarin & E. L. F. Menezes on the rock outcrops of the Espinhaco Range, Minas Gerais, Brazil. Note the creeping stem on the rock.

Figure 2. Vanilla rupicola Pansarin & E. L. F. Menezes A part of a flowering plant showing the stem and a lateral inflorescence with a typical-colored flower B detail of an apical inflorescence of an albino plant. Note the white flower C leaf and inflorescence D detail of a raceme. Note the adpressed floral bracts E dissected perianth. The detail shows the penicillate callus and the central labellar crest F detail of the adaxial surface of a petal showing the longitudinal keel G detail of a flower with a typical color showing the apex of the labellum, the penicillate callus and anther H detail of an albino flower showing the apex of the labellum, the penicillate callus and anther. Note that the labellum apex is more projected than in the typically-colored flower I detail of the apex of the labellum of a typically-colored flower showing the yellowish longitudinal lines and the yellow projections J detail of the apex of the labellum of an albino flower showing the whitish projections K labellum in lateral view L column in lateral view M apex of the column: in lateral view with an articulated anther (above), in lateral view with a disarticulated anther (mid), and in abaxial view (below) N immature fruit.