Gastrochilus pechei (Reichenbach f.) Kuntze (1891: 661)

Liu, Qiang, Zhou, Shi-Shun, Li, Ren, Tan, Yun-Hong, Zyaw, Myint, Xing, Xiao-Ke & Gao, Jiang-Yun, 2020, Notes on the genus Gastrochilus (Orchidaceae) in Myanmar, PhytoKeys 138, pp. 113-123 : 113

Gastrochilus pechei (Reichenbach f.) Kuntze (1891: 661) Figure 3

Saccolabium pechei Reichenbach f. (1889: 447) (Basionym)

Type.

MYANMAR. s. coll., s. n. (Holotype: K!)

Description.

Epiphytic herbs. Stem 1.0-1.5 cm, stout, with 4-5 leaves. Leaves nearly basal, distichous, oblong, 15-20 × 3.5-4.5 cm, slightly fleshy or leathery, apex obtuse and unequally 2-lobed. Inflorescences 1-4, from base of stem, sub-umbellate, often 4-6-flowered; peduncle straight, 1.5-2.5 cm, stout, with 2 cupular sheaths. Flower with yellow sepals and petals and white labellum, all dense with purplish spots. Sepals similar, spatulate, 11.8-12.5 × 4.2-5.4 mm, base contracted, apex obtuse. Petals spatulate, 11.5-11.7 × 4.0-4.2 mm, apex obtuse. Lip with an epichile and a saccate hypochile; epichile subtriangular, 5.0-5.2 × 15.1-15.4 mm, fleshy, adaxially glabrous, with a central cushion with a yellow blotch, margin irregularly erose, apex acute; hypochile subglobose, ca. 8 mm tall, ca. 8.4 mm in diameter, white tinged with yellow at bottom, outside with 5 ridges. Column ca. 3 mm, stout; rostellum deeply 2-lobed; pollinia 2, ca. 1.2 mm in diam.; stipe elongate, ca. 1.5 mm; anther cap nearly subglobose, apex narrowed into a beak.

Phenology.

Flowering occurs in August and September.

Distribution and habitat.

Gastrochilus pechei was originally recorded from Myanmar without detailed information about locality. Here in the manuscript, we have confirmed the occurrence of this species in north Myanmar in the Naungmeng town, Putao county, Kachin state. It was growing epiphytically on the trunk of riparian trees in tropical rainforest which is dominated by Dipterocarpus obtusifolius Teijsm. ex Miq. ( Dipterocarpaceae ).

Additional specimens examined.

MYANMAR. Kachin State. Putao County, Naungmeng town, tropical forest, 700-800 m a.s.l., epiphyte on the trunk of riparian trees, 8 August 2017, Qiang Liu 470 (HITBC!).

Note.

Gastrochilus pechei was only known from the type specimen until recently and, because this specimen was poorly preserved and severely shrunk, the key morphological characters of this species, such as flower colour and shape, were hard to interpret. As far as we can tell, there had been no subsequent collections of this species since 1889. Now that fresh material has become available, a detailed description of the species, including the plant and flower characters and information of distributed location, habitat and altitude, can be provided here. Morphologically, it shows a close affinity to G. obliquus , G. somai and G. arunachalensis . However, it differs from G. obliquus by having the slightly irregularly erose margin on the epichile, apex of epichile acute and subglobose hypochile (significantly lacerate or erose on epichile margin, apex of epichile obtuse and subglobose-cucullate and laterally compressed hypochile in G. obliquus ) ( Chen et al. 2009); from G. somai , it can be differentiated on being a large plant (leaves 15-20 × 3.5-4.5 cm), yellow sepals and petals and white labellum, all densely covered with purplish spots (smaller plant (3.5-4.2 × 1.2-1.7 cm), yellow-green sepals and petals without purplish spots and white labellum with yellow blotch on the centre of the epichile in G. somai ) ( Jin et al. 2010); from G. arunachalensis , by having spathulate sepals and petals, sub-triangular epichile with central cushion and subglobose hypochile (oblanceolate sepals and petals, triangular epichile without central cushion and cupular hypochile in G. arunachalensis ) ( Rao 1992).

Discussion.

The orchid flora of Myanmar is highly diverse but poorly known due to very few comprehensive studies. According to our current knowledge, about 800 orchid species are distributed in Myanmar ( Kurzweil and Lwin 2014), but this is probably an underestimate. Many new distribution records and new species have been published in the last few years ( Aung et al. 2017; Liu et al. 2017, 2018; Yang et al. 2017; Aung and Jin 2018, Zhou et al. 2018).

Although the genus of Gastrochius is small, it is easy to be confused with other taxa of Aeridinae when it is without flowers and is also difficult to be identified within species even during the flowering period. So, many species may be misidentified as other taxa. Meanwhile, Myanmar lies in southeast Asia, with the northern part bordering with southwest China and India and the southern part connecting with Thailand, all of these regions being rich in species of Gastrochilus . Therefore, we believe that more and more species of Gastrochilu s will be found when undertaking further field investigations and systematic studies.

Figures

Figure 3. Gastrochilus pechei A plant B sepals and petals C front view of flower D lateral view of flower E adaxial labellum F abaxial labellum G pollinarium H anther cap.