Habenaria canastrensis J.A.N.Bat. & B.M.Carvalho, 2010

Batista, João A. N., Ramalho, Bruno M. Carvalho Aline J. & Bianchetti, Luciano B., 2010, Three new species of Habenaria (Orchidaceae) from Serra da Canastra, Minas Gerais, Brazil, Phytotaxa 13, pp. 27-39 : 34-38

Habenaria canastrensis J.A.N.Bat. & B.M.Carvalho , sp. nov. ( Figs. 2 , 4 )

Ad Habenariam culicinam accedit sed petalorum segmento anteriore proportione breviore (1.2–1.3-plo segmenti posterioris longitudinem) et calcari minore (3.7–4.8 mm), breviore quam ovario et pedicello, differt. Etiam H. sancti-simonensi similis sed distinguitur sepalorum lateralium apice non aristato. Ac distinguitur ab H. pseudoculicina ovario et pedicello minoribus (7.0– 10.5 mm) atque calcari breviore.

Type:— BRAZIL. Minas Gerais: São Roque de Minas, Parque Nacional da Serra da Canastra, cerca de 35 km a partir da portaria principal de São Roque de Minas em direção a Sacramento , 20°11’53.2”S, 46°38’47.4”W, 1349 m, 13 December 2007 (fl), Batista & Carvalho 2344 (holotype: BHCB, isotype: CEN) .

Terrestrial herb. Tuber and roots not examined. Stem erect, 18–43 cm long, including inflorescence, 0.6–1.8(– 2.0) mm wide. Leaves (3–)4–5(–6), erect, adpressed to the stem, widest at the middle, linear-ensiform, 2.5– 8.0(–13.0) × 0.3–0.4 cm, membranous, soft. Inflorescence (2.3–)3.0–17.0(–21.0) cm long, spiral; bracts ovate-lanceolate, apiculate, 3.5–13.0(–35.0) × 2.8–3.8 mm, the lowest ones about same size or longer than ovary and pedicel, decreasing in size apically. Flowers 3–25(–37), green; ovary and pedicel mostly parallel to rachis, 7.0– 10.5 mm long, ovary slightly arched, 5.0– 8.5 mm long, pedicel 1–2 mm long. Sepals green, acute, margins smooth; dorsal sepal concave, when flattened slightly ovate, 3.5–4.3(–5.0) × 2.8–3.5 mm; lateral sepals obliquely lanceolate, subacute, reflexed, 3.7–4.5(–5.2) × 1.1–1.5 mm, mucronate. Petals bipartite, basally whitish, turning apically green; posterior portion falcate, 3.0–4.0 × 1.0– 1.5 mm, subacute, free from the dorsal sepal; anterior segment reflexed, linear-filiform, inserted a few mm higher in the posterior segment, 3.6–5.3 × 0.3–0.4 mm, 1.2 to 1.3 times as long as the posterior segment. Lip tripartite, base whitish, turning light green apically, undivided basal portion short, 0.3–0.5 × 0.7–1.2 mm; side lobes erect, reflexed, linearfiliform, 3.0–5.0 × 0.3–0.4 mm, 1.2 to 1.3 times as long as the midlobe; midlobe linear, straight, 4.0–6.0 × 0.5–0.9 mm. Spur slightly projecting forward, free from the bracts, slightly clavate, shorter than ovary and pedicel, 3.7–4.8 × 0.5–1.0 mm, base 0.3–0.4 mm wide, whitish, apex 0.4–0.9 mm wide, green. Column erect, 1.4–1.7 mm long; connective emarginate, light green; auricles fleshy, verrucose, whitish, 0.7–0.8 × 0.2–0.3 mm. Anther locules 1.2–1.3 mm long, canals short; hemipollinaria 2, joined by the viscidia. Stigma lobes 2, closely parallel, oblong, 1–1.3 mm long, greenish, receptive part ca. 0.6 × 0.3 mm each, flat, turned upwards, obtuse, margins slightly protruding; rostellum 0.8 mm long, greenish; midlobe triangular, fleshy, obtuse, erect, situated between the anther locules, 0.4 mm long; side lobes convergent apically, 0.4 mm long.

Distribution:—Known only from Serra da Canastra National Park located in the southwestern part of Minas Gerais.

Habitat, ecology and phenology:— Habenaria canastrensis grows in seasonally wet meadows, with dark, shallow soil, frequently associated with rock outcrops. Flowering occurs during the peak of the rainy season from December to January. Like other terrestrial species of Orchidaceae and Habenaria from tropical grasslands, fires during the dry season promote flowering, as great concentrations of flowering individuals were always observed in previously burned areas.

Etymology:—Named after Serra da Canastra.

Conservation status:—Using the World Conservation Union Red List Categories and Criteria ( IUCN, 2001) H. pseudoculicina can tentatively be classified as endangered due to the limited geographic range [B1ab(iii)+2ab(iii)]. However, although the species is known only from the Chapadão da Canastra in the Serra da Canastra National Park, it is locally common and widespread in that area.

Additional specimens examined:— BRAZIL. Minas Gerais: São Roque de Minas, Parque Nacional da Serra da Canastra, entre a portaria principal a partir de São Roque de Minas e a nascente do Rio São Francisco , 20°15’40.7”S, 46°25’37.3”W, 1370 m, 8 January 2007 (fl), Batista et al. 1801 ( BHCB) ; 6.9 km a partir da portaria principal de São Roque de Minas, em direção a Sacramento, cerca de 1.1–1.3 km após a nascente do Rio São Francisco , 20°14'01.1"S, 46°26'40.1"W, 1380 m, 9 January 2007 (fl), Batista et al. 1806 ( BHCB) ; cerca de 30 km a partir da portaria principal de São Roque de Minas , em direção a Sacramento, campos a esquerda da estrada a partir da entrada da Casca D'Anta, 20°16'03.1"S, 46°33'23.3"W, 1425 m, 10 January 2007 (fl), Batista et al. 1825 ( BHCB) ; 1 January 1999 (fl), Bertioli 15 ( CEN) ; Guarita de Sacramento , 11 January 1998 (fl), Romero et al. 4982 ( HUFU) .

Habenaria canastrensis is similar to H. culicina . However, the two species differ in the length of the petal anterior segment relative to the posterior segment (1.2 to 1.3 times as long in H. canastrensis versus 2.3 to 2.6 times as long in H. culicina ) and length of the spur (3.7–4.8 mm and shorter than the ovary and pedicel in H. canastrensis versus 7.0–8.0 mm and approximately the same length as the ovary and pedicel in H. culicina ). The two species also differ in relation to habitat. Habenaria canastrensis is typical of seasonally wet meadows (campo limpo estacionalmente úmido), whereas H. culicina grows in dry, open, grassy fields (campo limpo seco), grass-herb-subshrub field (campo sujo seco), over deep, well-drained, reddish, clay latosoils, and dry rocky field vegetation (campo rupestre seco). Habenaria canastrensis is also similar to H. pseudoculicina , but the two species can be differentiated by the characters outlined for H. pseudoculicina .

Another species to which H. canastrensis can be compared is H. sancti-simonensis Hoehne (1915: 37) , known only from the type material from Mato Grosso, but plants of H. canastrensis are smaller (18–43 cm high including the inflorescence versus 40–60 cm in H. sancti-simonensis ) and apices of the lateral sepals mucronate (versus aristate in H. sancti-simonensis ). Hoehne (1940) considered H. sancti-simonensis a synonym of H. culicina . However, H. sancti-simonensis seems to be closely related to H. ludibundiciliata J.A.N. Batista & Bianchetti (2006: 9) also characterized by the aristate sepals, a character absent in H. culicina .

Among the material examined of H. canastrensis , one population represented by the collection Batista et al. 1825 had some distinctive characters. The plants were collected in full bloom in January 2007 when all other populations of the species found in the park had no good flowers left and were in fruit; they occurred on a steep rocky field, were overall smaller (10–30 cm high) and bore fewer flowers (3–6); the spur was also slightly longer and clavate (4.9–6.2 × 0.6–1.2 mm). Due to these differences, measurements of the specimens of this population were not included in the description of H. canastrensis until the exact taxonomic status of this material is determined.

According to the sectional treatment of Habenaria in Flora Brasiliensis ( Cogniaux, 1893) the three new species should be placed in H. section Nudae Cogniaux (1893: 21). However, a phylogenetic analysis of the New World species based on nuclear and plastid DNA sequences indicated that as currently circumscribed H. sect. Nudae is polyphyletic, and further studies are necessary to determine relationships for these three new species.

Mountain areas throughout the world are recognized centers of plant diversity and endemism. In Brazil, the Serra da Canastra is particularly interesting due to its intermediate location between the Brazilian central plateau and the Serra da Mantiqueira range; however, the floristic composition and affinities of the region have not been studied in details. A preliminary survey identified 45 species of plants, belonging to several families, endemic to Serra da Canastra National Park ( Romero & Nakajima 1999). However, since Orchidaceae were not included in that study, H. canastrensis and H. pseudoculicina are the first records of endemic taxa of Orchidaceae for Serra da Canastra and further highlight the rich endemic flora of the region.

Figures

FIGURE 2. A. General view of Serra da Canastra during the rainy season in January 2007. B. Habitats of H. psammophila and H. pseudoculicina, seasonally wet meadows (campo limpo estacionalmente úmido), on the foreground, and of H. canastrensis, rocky field (campo rupestre), on the background. Flowers from live specimens. Habenaria psammophila. C. Part of inflorescence. D. Flowers. E-F. Habenaria canastrensis. G. Habenaria pseudoculicina. H. H. culicina. Scale bars = 3 mm. C-D. Batista et al. 1794 (BHCB). E-F. Batista & Carvalho 2344 (BHCB). G. Batista et al. 1808 (BHCB). H. Batista 634 (CEN).

FIGURE 4. Habenaria pseudoculicina. A. Habit. B. Leaf. C. Flower, front view. D. Flower, ¾ lateral view. E. Perianth. F. Bract, pedicel, ovary, column and spur, side view. G.Column, lateral view. H. Column, front view. I. Rostellum, upper view. J. Rostellum, lateral view. Batista et al. 1808 (BHCB).