Monday, August 23, 2021

[Botany • 2021] Dendrobium parahendersonii • A New Orchid Species (sect. Crumenata: Orchidaceae) from Southern Vietnam


Dendrobium parahendersonii Vuong, Aver. & V.C. Nguyen, 

in Nguyen, Averyanov, Maisak, ... et Truong, 2021.

Abstract
Dendrobium parahendersonii discovered in southern Vietnam is described as new species to science. It belongs to D. sect. Crumenata, and resembles D. hendersonii and D. exile in having a filiform, reed-like stem swollen at the base into a quadrangular ellipsoid pseudobulb and flowering from the leafless part of stem but differs clearly in the details of its tepals and lip. A morphological description, illustrations, data on habitat, phenology, and conservation status for the new species are provided.

Keyword: Crumenata, Dendrobium hendersonii, new species, Orchidaceae, plant diversity, plant taxonomy

 
Dendrobium parahendersonii Vuong, Aver. & V.C. Nguyen.
 A. Flowering shoots. B. Swelling basal parts of stems (pseudobulbs). C. Cross section of the swelling part of stem. D. Leaves, adaxial and abaxial surface. E. Flowers, view from different sides. F. Median sepal (fresh and alcohol preserved). G. Lateral sepals (fresh and alcohol preserved). H. Petals (fresh and alcohol preserved). I. Lip, view from different sides. J. Column, pedicel, and ovary, side view. K. Column and column foot, view from different sides. L. Anther cap, view from different sides. M. Pollinaria.
 Photos by Truong Ba Vuong from plant used for preparation of the holotype (Truong Ba Vuong et al., BV 1142). Photo correction and design by L. Averyanov and T. Maisak.



Dendrobium parahendersonii Vuong, Aver. & Nguyen V.C., sp. nov. 

Diagnosis. The new species is morphologically similar to D. hendersonii but clearly differs by quadrangular pseudobulbs, quadrate or sub-quadrate in cross section (vs. pseudobulbs distinctly flattened, rhomboid in cross-section), smaller flower ca. 1 cm long (vs. 2–2.5 cm long), shorter pedicel and ovary ca. 5 mm long (vs. pedicel and ovary up to 1 cm long), smaller median sepal ca. 5 mm long, 2 mm wide (vs. median sepal 10–15 mm long, 4–6 mm wide), median lip lobe halfcircular (vs. median lip lobe narrowly oblong), lip disc with 5 distally fimbriate keels (vs. lip disc distally with almost glabrous tripartite callus). Morphological details of D. hendersonii used for the comparison are based on data reported by Wood (2015). 

Etymology. The species name refers its closest relation to D. hendersonii. Habitat and phenology. Trunk and branch epiphyte in broadleaved evergreen and semideciduous lowland and submontane forests at elevation 200–800 m a.s.l. Flowers all around the year, usually after light short weather cooling. 

Distribution. Vietnam, provinces Dong Nai (Vinh Cuu District), Khanh Hoa (Ninh Hoa District), and Lam Dong. Endemic of the eastern part of Central Highlands in southern Vietnam.


Van Canh Nguyen, Leonid V. Averyanov, Tatiana V. Maisak, Thi Lien Thuong Nguyen, Van Khuong Nguyen and Ba Vuong Truong. 2021. Dendrobium parahendersonii, A New Orchid Species (Orchidaceae) from Southern Vietnam. Taiwania. 2021 66(3); 360-363. DOI: 10.6165/tai.2021.66.360