Platanthera medogensis X.H. Jin & D.L. Lin

Lin, Dongliang, Li, Jianwu, Ye, Chao, Wen, Haixia & Jin, Xiaohua, 2024, A new species of Platanthera (Orchidaceae, Orchideae) from southeast of Xizang, China, Phytotaxa 646 (2), pp. 116-124 : 117-121

Platanthera medogensis X.H. Jin & D.L. Lin , sp. nov. ( Figure 2 , 3 )

Type:— CHINA. Xizang Autonomous Region, Nyingchi City, Motuo County, Gedang , terrestrial under humid alpine conifer forests, 3450 m, 31 Jul 2023, Xiaohua Jin et al. 40288 (holotype PE!, isotypes, PE!) .

Diagnosis. Platanthera medogensis is close to P. bakeriana and P. chiloglossa , but is readily distinguished from P. bakeriana by having spur slightly longer than ovary (vs. more than twice in P. bakeriana ) and ovate-lanceolate lip concave at base with two calli, and from P. chiloglossa in its linear viscidia (vs. narrowly oblong viscidia) and ovate-lanceolate lip concave at base with two calli ( Table 1 ).

Herbs, terrestrial, plants 25 cm tall. Rootstock creeping, fleshy, cylindric, stout. Stem erect, with 1 tubular membranous sheath at the base, 2-leaved. Basal leaf oblong-elliptic, 11× 1.3 cm, narrowing, clasping the stem, apex acute or obtuse-rounded; the upper leaf smaller, ovate-lanceolate, 3.5× 0.8 cm. Sterile bracts foliaceous, ovate-lanceolate, 2× 0.3 cm; raceme ca. 11 cm long, with 5–13 sparsely arranged flowers. Floral bracts ovate-lanceolate, equal to or slightly shorter than the ovary, 1× 0.3 cm, apex acute; flowers yellow-green; ovary arcuate, cylindric, tapering towards the upper part, ovary and pedicel ca. 1 cm long. Dorsal sepal ovate, concave, ca. 0.4× 0.2 cm, apex acute, one-veined; lateral sepals reflexed, ovate, oblique, 0.4× 0.1 mm, apex acute; petals ovate-elliptic, 0.4× 0.2 cm, apex slightly obtuse, erect, fused with dorsal sepal to form a hood-like structure, thickened on the side adjacent to the lip; lip ovate-lanceolate, apex acute, base concave and, with 2 horn-like calli, margins erect at base; 0.3× 0.2 cm; spur pendulous, cylindric, slightly longer than ovary, apex acute, about 1.2 cm long. Column short, ca. 0.5 mm long; anther locules almost parallel, about 1 mm long; connective narrow; pollinia elongate-obovoid, ca. 1 mm in diameter, attached to slender stalks and linear viscidia; staminodes 2, located on both sides of the base of anther locules, spherical, about 0.2 mm; rostellum concave, triangular, short; stigmas 2, slightly protruding, located below the rostellum, positioned behind the mouth of spur.

Etymology: The epithet “ medogensis ” refers to the type locality of the new species, Motuo county, Xizang, China.

Distribution and habitat: P. medogensis grows under the subtropical alpine conifer forests of Abies , at elevation of ca. 3450m.

Phenology: Flowering in July–August.

Figures

FIGURE 2. Habitat and close-up of Platanthera medogensis A. Conifer forest; B. Plants; C. and D. Front view of flowers.

FIGURE 3. Plants of Platanthera medogensis. A. Plant. B. Sterile bract. C. Floral bracts adaxial view (left) and abaxial view (right). D. Lateral view of flower. E. Sepals, petals, and lip (adaxial sides). F. Sepals, petals and lip (abaxial sides). G. Lateral view of column, ovary and lip with spur. H, J. Front view of column. I. lip, with red arrows indicating two calli at the base of lip. K. pollinia with caudicles and viscidia.