Balang Mountain orchid (Gastrochilus balangshanensis), new subalpine epiphytic orchid from Southwest China
NEWS - Balang mountain orchid (Gastrochilus balangshanensis), a new epiphytic orchid species from Balang Mountains, Sichuan Province, Southwest China, with flowers morphologically resembling G. affinis, but differing in having a shorter stem, reniform epichile and sub-hemispherical hypochile (spur) and blunt-rounded at the apex.
Molecular phylogenetic analysis based on nuclear ribosome internal transcribed spacer (nrITS) and four chloroplast DNA markers (matK, psbA–trnH, psbM–trnD and trnL–F) of 50 Gastrochilus species showed G. balangshanensis is closely related to G. heminii and G. bernhardtianus which are also endemic to the Hengduan Mountains.
This supports the recognition of a neglected center of endemism, which may be related to rapid allopatric speciation in nearby mountains within G. sect. Microphylli which now numbers 11 species.
In terms of morphological characteristics, including leaf shape, leaf size and color markings, G. balangshanensis is most similar to G. bernhardtianus and G. heminii. However, based on overall flower characters and color, G. balangshanensis is most similar to G. affinis. This may be explained by parallel evolution.
G. balangshanensis differs from G. affinis in having a stem 1.5-3.5 cm (vs. 3.0-12.0), leaves nearly elliptic (vs. oblong-lanceolate to subspathulate), sepals 5.6-6.4 × 4.8-5.2 mm (vs. 3.0-5.0 × 1.0-1.3), petals 5.0-5.8 × 4.0-4.4 mm (vs. 3.0-4.0 × 1.0-1.3), epichile reniform (vs. subtriangular) and hypochile sub-hemispherical, obtuse-rounded at the apex (vs. hypochile obconical, subacute to obtuse and soon bifurcated at the apex).
The new species is known only from Yinchanggou, Mount Balang, part of the Hengduan Mountains. This plant is an epiphyte on tree trunks or branches in subalpine mixed conifer forests dominated by Abies fargesii var. faxoniana at an elevation of 2200-2300 meters, coexisting with terrestrial orchids, Goodyera recurva Lindl. and Calanthe arcuata Rolfe.
Flowering from March to April, during the dry season, fruiting from May to September. The name refers to Mount Balang, the location of this new orchid species. The researchers suggest the Chinese name, “ba lang shan peng ju lan” (巴朗山盆距兰).
Hengduan Mountains are part of the Tibeto-Himalayan region which has a very diverse flora. Researchers have previously discovered new species of Gastrochilus in Wenchuan, including G. wolongensis Jun Y. Zhang, B. Xu & Yue H. Cheng 2022, G. heminii M. Liao, B. Xu & Yue H. Cheng 2022, G. armeniacus Jun Y. Zhang, B 024.
Original research
Zhang J-Y, Cheng Y-H, Liao M, Jin S-L, Lin H-Q, Yang P-Y, He H, Xu B (2024). Gastrochilus balangshanensis (Orchidaceae, Aeridinae), a new subalpine epiphytic orchid from the Mountains of Southwest China. PhytoKeys 247: 123-135, DOI:10.3897/phytokeys.247.130755
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