Habenaria karstica J.A.N.Bat., 2022

Batista, João A. N., Ferreira, Vera L., Alves, Camila I. G. & Stehmann, João R., 2022, A new species of Habenaria (Orchidaceae, Asparagales) and a checklist of Orchidaceae from limestone outcrops of Brazil, European Journal of Taxonomy 828, pp. 16-44 : 29-34

Habenaria karstica J.A.N.Bat. sp. nov.

urn:lsid:ipni.org:names:77299816-1

Figs 3–4

Diagnosis

Similar in general morphology to some species in the Habenaria repens complex, but differs from these and all other Neotropical species of the genus for growing on limestone outcrops, under full sun, associated with saxicolous plants, and by the combination of the following characters: leaves not pleated, pedicellate ovary 19–25 mm long, petal anterior segment about the same length as the posterior segment (ratio 0.9–1.2), lip lateral segment about the same length as the median segment (ratio 0.9–1.0), spur 16–19 mm long, and rostellum mid lobe apex acute and erect. Distinct from the phylogenetically related species of the Habenaria sect. Spathaceae by the flowers completely green, pedicel 5–6 mm long, shorter than the ovary, pollinaria separate, and rostellum mid lobe completely held between the anther loculi.

Etymology

From the german ‘karst’ (limestone region), the specific epithet refers to the preference of this species for growing on limestone outcrops.

Type material

BRAZIL – Minas Gerais • Pedro Leopoldo, Lapa do Baú ; 19º32′54.4″ S, 43º59′34.1″ W; 750 m a.s.l.; 7 Jan. 2020; fl; J.A.N. Batista, V.L. Ferreira & G.V. A. dos Santos 3649; holotype: BHCB[204961] ; isotype: CEN; GenBank nrITS: ON197322 and ON197323 ; matK gene and trnK intron: ON168967 and ON168968 ; rps16-trnK intergenic spacer: ON168969 and ON168970 .

Other material studied

BRAZIL – Minas Gerais • Pedro Leopoldo, Lapa do Baú ; 19º32′55″ S, 43º59′35″ W; 715 m a.s.l.; 11 Dec. 2018; fl; V.L. Ferreira, J.R. Stehmann & G.V.A. Santos 126; BHCB .

Description

Geophytic herb, caulescent, sympodial. Roots 1.4–1.6 mm wide, up to 7 cm long; tuberoid ca 3.6 × 1.7 cm, elipsoid. Stem 47–62 cm long including the inflorescence, 3.5–6.0 mm wide, erect. Leaves 4–6, spirally-alternate, lanceolate, membranaceous, the largest concentrated in the middle of the stem, 10– 18 × 1.8–3 cm, reducing towards the apex of the stem, base sheathing, sheath closed, blade patent, apex acute. Inflorescence 10–13 cm long, spiral, 0.7–1.2 flowers/cm of the rachis; floral bracts 14–36 mm long, about the same size as the pedicellate ovary, decreasing in size towards the inflorescence apex, green, ovate to lanceolate, apex acuminate. Flowers 8–14, resupinate, green, glabrous; pedicellate ovary 19–25 mm long, mostly straight, more or less parallel to the rachis axis or ascending, apex curved; ovary 15–19 mm long, pedicel 5–6 mm long. Sepals green, margin smooth; dorsal sepal 8.0–9.0 × 6.0 mm, concave, ovate when flattened, apex mucronate; lateral sepals 10.0–11.0 × 4.0 mm, abaxially concave, obliquely lanceo-ovate, patent, the distal third reflexed, apex mucronate. Corolla light green. Petals bipartite; posterior segment 8.0–10.0 × 1.6–2.0 mm, narrowly triangular, falcate, apex acute, free from the dorsal sepal to connivent; anterior segment 8.0–9.0 mm long, 0.9–1.2 times as long as the posterior segment, filiform, inserted at the base of the posterior segment. Labellum tripartite; undivided basal part 1.3–2.2 × 2.5–3.0 mm; lateral segments 9–10× 0.8–1.0 mm, 0.9–1.0 times as long as the median segment, reflexed; median segment 10–11 × 1.3–1.5 mm, linear, straight; spur 16.0–19.0 × 1.6–2.0 mm, 0.8–0.9 times as long as the pedicellate ovary, deflexed, parallel to the pedicellate ovary, apex covered by the bract, linear to slightly clavate, green. Gynostemium ca 3.3 mm high, erect; connective light green, apex emarginate; lateral appendages (auricles) 2.2–2.4 × 0.6 mm, fleshy, verrucose, erect, translucent. Anther 1.6–1.7 × 1.3 mm, bilocular, loculi parallel, translucent; canals parallel, projected forward, more or less perpendicular to the loculi; pollinaria 2, separate; caudicles 1.2 mm long, filiform, pale yellow; pollinia 4, 1.2 × 0.7 mm, elliptical, yellow; viscidia 0.4 × 0.3 mm, ellipsoidal, whitish, 1.0 mm apart from each other. Stigmatophores (stigma lobes) 2, ca 1.8 mm long, parallel, light green, receptive surface 0.7 mm long, convex, mostly turned frontwards, 0.5 mm wide each. Rostellum ca 2.7 mm long; mid lobe ca 1.2 mm high, triangular, erect, held between the anther loculi, fleshy, translucent, apex light green, acute; side-lobes 1.1 mm long, parallel throughout.

Ecology and phenology

Habenaria karstica sp. nov. grows in limestone outcrops, under full sun, in soil patches accumulated at the base of Dyckia luxor (L.B.Sm. & Read) Forzza , which forms large colonies on the rock, or in

small pockets of earth between rocks ( Fig. 3 ). The plants begin to grow in late November and early December, at the beginning of the rainy season and bloom from mid-December to January. Several species of orchids also occur on the same limestone outcrop, but only Cyrtopodium glutiniferum grows under the same conditions. However, this species is much stouter and forms large clumps with exposed, fusiform pseudobulbs up to 90 cm in length ( Batista & Bianchetti 2021). Other species such as Cattleya cernua (Lindl.) Van den Berg , C. lundii (Rchb.f. & Warm.) Van den Berg , Campylocentrum neglectum (Rchb.f. & Warm.) Cogn. , Myoxanthus lonchophyllus (Barb.Rodr.) Luer , and Trichocentrum pumilum (Lindl.) M.W.Chase & N.H.Williams occur on the same outcrop, but all are epiphytes and grow on isolated trees or in the forests surrounding the rock massif.

Distribution and conservation assessment

Habenaria karstica sp. nov. is so far known from a single limestone outcrop called Lapa do Baú in the municipality of Pedro Leopoldo, in the State of Minas Gerais. This population is restricted to a small massif area, and in December 2020, we observed only about 15 individuals with growing inflorescences. The place is a private property inserted in a conservation unit of sustainable use (APA Carste de Lagoa Santa), and although the surrounding area has been completely converted to cultivated land and pasture, the massif is relatively preserved. However, there is an intense limestone mining activity in the region, and several outcrops have been destroyed ( de Deus et al. 2013). According to the IUCN Red List Categories and Criteria and the guidelines ( IUCN 2012, 2016), the species can tentatively be classified as Critically Endangered (CR), due to its small area of occupancy, estimated to be 4 km 2, and the fact that it is known from a single small population [B1ab(iii) + 2ab(iii); D].

Taxonomic notes

In the general morphology of flowers, H. karstica sp. nov. is similar to some species of the Habenaria repens complex ( Lau et al. 2021), such as H. coxipoensis Hoehne , H. rupicola Barb.Rodr. , H. sampaioana Schltr. , and H. subviridis Hoehne & Schltr. ( Fig. 5 ). Based only on morphological characters, separating these species is difficult, and there is overlap with one or another species in all characters examined ( Table 2 ). In addition to the very specific habitat, H. karstica can be morphologically differentiated from these species by a combination of characters, which include: leaves patent, distributed along the stem, leaf blade not plicate, pedicellate ovary 19–25 mm long, petal anterior segment about the same length as the posterior segment (ratio 0.9–1.2), lip lateral segment about the same length as the median segment (ratio 0.9–1.0), spur 16–19 mm long, and rostellum mid lobe apex acute and erect ( Table 2 ).

Figures

Fig. 3. Lapa do Baú, Pedro Leopoldo, during the rainy season. A. General view of the outcrop. B. View of the massif with predominance of Dyckia luxor (L.B.Sm. & Read) Forzza. C–E. Habenaria karstica J.A.N.Bat. sp. nov. C. Plants growing at the base and between D. luxor. D. Plants growing in small pockets of soil accumulated between rocky blocks. E. Flowers.

Fig. 4. Habenaria karstica J.A.N.Bat. sp. nov. A. Habit. B. Stem base, roots and tuberoid. C. Leaf. D. Flower, front view. E. Flower, side view. F. Pedicellate ovary, gynostemium, lip and spur, side view. G. Dissected perianth. H. Gynostemium, front view. I. Gynostemium, lateral view. J. Gynostemium, dorsal view. K. Dissected connective, anthers and auricles. L. Pollinaria. M. Rostellum, side view. N. Rostellum, upper view. All images from the type material, J.A.N. Batista et al. 3649 (BHCB).

Fig. 5. A. Habenaria karstica J.A.N.Bat. sp. nov. (Batista et al. 3649 – BHCB). B–F. Species of the Habenaria repens complex morphologically similar to H. karstica. B. Habenaria rupicola Barb. Rodr. (Batista et al. 2782 – BHCB). C. Habenaria sampaioana Schltr. (Batista et al. 2426 – BHCB). D. Habenaria coxipoensis Hoehne (Batista 404 – CEN). E. Habenaria subviridis Hoehne & Schltr. (Batista 2605 – BHCB). F. Habenaria aranifera Lindl. (Batista 2472 – BHCB). G–L. Species phylogenetically related to H. karstica from Habenaria sect. Spathaceae Kraenzl. G. Habenaria anistisii Kraenzl. (Batista & Bianchetti 3087 – BHCB). H. Habenaria curti-bradei Hoehne (Batista et al. 2372 – BHCB). I. Habenaria heringeri Pabst (Batista 21 – CEN).J. Habenaria jaguariahyvae Kraenzl. (Batista et al. 1824 – BHCB). K. Habenaria orchiocalcar Hoehne (Batista 173 – CEN). L. Habenaria trifida Kunth (Batista et al. 2724 – BHCB). Scale bars: A–F = 5 mm; G–L = 10 mm.