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Issue: Vol. 747 No. 1: 13 Mar. 2026
Type: Article
Published: 2026-03-13
DOI: 10.11646/phytotaxa.747.1.5
Page range: 81-94
Abstract views: 0
PDF downloaded: 0

Taxonomic notes on Dendrobium sect. Pedilonum (Orchidaceae): a new species, D. nakhonsiense, from Thailand and the D. cumulatum s.l. complex revisited

Department of Plant Science, Faculty of Science, Mahidol University, 272, Rama 6 Road, Ratchathewi, Bangkok 10400, Thailand; The Botanical Garden Organization, Queen Sirikit Botanic Garden, Mae Rim, Chiang Mai 50180, Thailand
Natural History Museum of Denmark, University of Copenhagen, Gothersgade 130, DK-1123 Copenhagen K, Denmark; Herbarium, Science, Royal Botanic Gardens, Kew, Richmond TW9 3AE, United Kingdom
Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Chatuchak, Bangkok 10900, Thailand
Department of Plant Science, Faculty of Science, Mahidol University, 272, Rama 6 Road, Ratchathewi, Bangkok 10400, Thailand
plant distribution endemism lectotypification orchids plant systematics Monocots

Abstract

This study presents a classical taxonomic approach to parts of Dendrobium sect. Pedilonum, focusing on a newly discovered species from Thailand and the D. cumulatum s.l. species complex. The new species, D. nakhonsiense seems endemic to Nakhon Si Thammarat Province in Peninsular Thailand where it is only known from one location. It is morphologically close to D. cowenii but is distinguished by its slightly larger flowers with a relatively longer, obtuse to rounded mentum and by its differently shaped dorsal sepal and labellum lamina. The D. cumulatum s.l. complex includes four taxa, viz. D. cumulatum, D. rhodocentrum, D. eoum, and D. calicopis. Based on extensive herbarium studies and morphological comparisons, we propose the recognition of two distinct species: D. cumulatum (syn.: D. rhodocentrum, D. calicopis) and D. eoum. Our findings contribute to the understanding of species diversity and distribution within Dendrobium sect. Pedilonum.

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How to Cite

Rujichaipimon, W., Pedersen, H. Æ., Suddee, S. & Traiperm, P. (2026) Taxonomic notes on Dendrobium sect. Pedilonum (Orchidaceae): a new species, D. nakhonsiense, from Thailand and the D. cumulatum s.l. complex revisited. Phytotaxa 747 (1): 81–94. https://doi.org/10.11646/phytotaxa.747.1.5