Research Article
Print
Research Article
Corybas papillatus (Orchidaceae), a new orchid species from peninsular Thailand
expand article infoJanejaree Inuthai‡, Sahut Chantanaorrapint§, Manop Poopath|, Naiyana Tetsana|, Wittawat Kiewbang, Somran Suddee|
‡ Thammasat University, Lampang, Thailand
§ Prince of Songkla University, Songkhla, Thailand
| Department of National Parks, Wildlife and Plant Conservation, Bangkok, Thailand
¶ Forest Economics Bureau, Royal Forest Department, Bangkok, Thailand

Corresponding author: Sahut Chantanaorrapint ( sahut.c@psu.ac.th )

Academic editor: Yasen Mutafchiev
© 2021 Janejaree Inuthai, Sahut Chantanaorrapint, Manop Poopath, Naiyana Tetsana, Wittawat Kiewbang, Somran Suddee.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Inuthai J, Chantanaorrapint S, Poopath M, Tetsana N, Kiewbang W, Suddee S (2021) Corybas papillatus (Orchidaceae), a new orchid species from peninsular Thailand. PhytoKeys 183: 1-7. https://doi.org/10.3897/phytokeys.183.71167
Open Access

Abstract

A new species, Corybas papillatus, is described and illustrated from peninsular Thailand. The new species is easily recognized through a combination of the following characters: the purplish flower, the rounded apex of the dorsal sepal, the outer surface of dorsal sepal covered with irregular papillae in the upper half, the lateral sepals adnate laterally at the base to the connate petals, the V-shaped throat, the labellum bearing short hairs, dentate to erose labellum margins, and well-developed conical spurs. A key to the species of Corybas in Thailand is presented.

Keywords

Helmet orchid, Khao Luang National Park, montane forest, Thai-Malay Peninsula

Introduction

Corybas Salisb. is a genus of terrestrial orchids comprising about 120 species, and is widely distributed from India, South China, peninsular Thailand, the Malesian region, to New Zealand and the Western Pacific Islands (Dransfield et al. 1986; Pridgeon et al. 2001; Pedersen 2011; Tandang et al. 2020). The members of the genus are easily recognized by being small in size with a single cordate leaf and 1–2 underground tubers, dorsal sepal and labellum which together form a tube with expanded mouth, lateral sepals and petals often antenna-like, and labellum usually bearing two spurs (Dransfield et al. 1986). Only two Corybas species are currently known from Thailand, namely Corybas ecarinatus Anker & Seidenf. (Anker and Seidenfaden 2001; Pedersen 2011), and C. geminigibbus J.J. Sm. (Chantanaorrapint and Chantanaorrapint 2016).

During a recent visit to Khao Luang Mountain, Khao Luang National Park, by staff of BKF herbarium, an interesting taxon of the genus Corybas was collected with a unique combination of characters that did not match any of the known species. It is therefore described here as a species new to science.

Materials and methods

This study is based on material collected during July 2018 from Khao Luang National Park, Nakhon Si Thammarat province, southern Thailand. Specimens were preserved in alcohol (70% ethanol) and deposited in BKF herbarium. Morphological characters were studied using a stereo microscope Olympus SZX7 and the distinctive characters of the species were illustrated with the aid of an Olympus drawing tube. Measurements were taken from spirit material. The specimen details were compared in detail with original drawings and descriptions given in the protologues of Corybas species in the Malaysian region (e.g. Dransfield et al. 1986; Anker and Seidenfaden 2001; Tandang et al. 2020).

Taxonomy

Corybas papillatus Inuthai, Chantanaorr. & Suddee, sp. nov.

urn:lsid:ipni.org:names:77220208-1
Figs 1, 2

Diagnosis

Similar to Corybas villosus J. Dransf. & Gord. Sm., but differs in the absence of dorsal sepal keel and the lateral sepals adnate laterally at the base to the connate petals.

Type

Thailand. Nakhon Si Thammarat province, Khao Luang National Park, near summit of Khao Luang Mt., 08°29'36.8"N, 099°43'38.9"E, ca. 1,700 m alt., 4 July 2018, M. Poopath, N. Tetsana, W. Kiewbang, C. Hemrat & S. Jirakorn 2201 (holotype BKF!, spirit material).

Small terrestrial herb with underground tubers. Tubers globose or ovoid, fleshy, 3–4 mm diam. Stem erect, whitish-green, 5–12 mm long, 1–1.5 mm diam., with a basal sheath; stolon whitish, hairy, up to 2 cm long, 1–1.2 mm diam. Foliage leaf sessile, cordate, long acuminate at apex, glabrous, 6–10 mm long, 6–8 mm wide at the widest point, flat, only slightly undulate along margin, pale green with paler veins, the veins scarcely conspicuous. Inflorescence one-flowered, terminal; bract pale green, lanceolate-triangular, long acuminate, 5–6 mm long, recurved. Flower dark purple. Dorsal sepal purplish, erect below, then strongly curved above, hooded and clasping labellum throughout its length, spathulate, ca. 15 mm long, 8–10 mm wide, rounded at apex, apical margins denticulate, abaxial (dorsal) surface bearing irregular papillae in the upper half. Lateral sepals greenish-white, linear-triangular to antenna-like, ca. 25 mm long, laterally adnate to the petals in the basal ca. 1 mm. Petals greenish-white, connate at the base for ca. 1 mm, free above, similar to lateral sepals but shorter, ca. 22 mm long. Labellum differentiated into 2 parts, erect in basal half and strongly reflexed above, ca. 17 mm long in total length; the basal half with margins strongly inrolled throughout, and forming a tube with the dorsal sepal, ca. 7 mm long; the upper half reflexed and expanded, orbicular, ca. 10 mm diam., margin erose, reddish-purple excepted for a white zone just below the margins; mouth of throat very deeply V-shaped; adaxial surface bearing short hairs; spurs 2, divergent, conical, ca. 3 mm long. Column very short, ca. 1.5 mm long; stigma rounded, ca. 0.5 mm diam.; anther erect, smooth; pollinia not seen. Ovary green, glabrous, ca. 2 mm long. Capsule (immature) erect, ellipsoid or fusiform, 5–7 mm long, 2.5–3 mm diam. Seed not seen.

Phenology

Flowering and fruiting observed in July.

Habitat and ecology

The new species was found growing amongst bryophytes (Fig. 1A–C), such as Acroporium sp., Bazzania sp., and Schistochila aligera (Nees & Blume) J.B. Jack & Steph., on humus in shade in montane forest, ca. 1,700 m above sea level.

Figure 1. 

Corybas papillatus Inuthai, Chantanaorr. & Suddee A, B plants in natural habitat, on humus associated with Bazzania sp. and Acroporium sp. C plant with immature fruit D, E flowers D front view E lateral view F immature flower G underground parts with tubers. Photographs by W. Kiewbang.

Distribution

Corybas papillatus is only known from the type locality (Fig. 3), however, it may also occur in other areas in peninsular Thailand with similar vegetation type.

Etymology

The specific epithet ‘papillatus’ alludes to occurrence of irregular papillae in upper portion of abaxial (dorsal) surface of dorsal sepal.

Conservation status

We consider it likely that if a formal assessment were performed, this species would be categorized as Critically Endangered (CR (D)) based on a preliminary risk of extinction assessment using the IUCN red list categories and criteria (IUCN 2019). This species is known from only four individuals from the type locality which attracts high numbers of camping tourists. Although we returned to the same locality and tried to find more specimens in 2020 it could not be found again. The species is, however, easily be overlooked in the field because of its small size.

Figure 2. 

Corybas papillatus Inuthai, Chantanaorr. & Suddee A whole plant with flower and tubers B plant with immature flower C mature flower, lateral view D plant with immature fruit E floral bract, F, G dorsal sepal F ventral view G lateral view H lateral sepals and petals I labellum J, K column, J lateral view, K front view. Drawn by J. Inuthai.

Figure 3. 

Type locality of Corybas papillatus Inuthai, Chantanaorr. & Suddee (•).

Discussion

Corybas papillatus is most similar to C. villosus, which is endemic to Peninsular Malaysia (Dransfield et al. 1986; Go et al. 2015). These two species share several common features, viz. flower coloration being purplish, the dorsal surface of dorsal sepal covered with irregular papillae in the upper half, the hairiness of the labellum, the V-shaped throat, irregularly dentate to erose labellum margins, and well-developed conical spurs. Corybas papillatus is distinguished from C. villosus by lacking dorsal sepal keel (strongly keeled in C. villosus) and the adnate lateral sepals and connate petals (all free in C. villosus).

Corybas papillatus might be confused with C. ridleyanus Schltr., another endemic to Peninsular Malaysia (Dransfield et al. 1986; Go et al. 2015), which also has purplish flowers and reddish-purple labellum excepted for a zone below the margin, and a V-shaped throat. Corybas ridleyanus, however, differs from C. papillatus by the truncate apex of the dorsal sepal and the free lateral sepals and petals.

Together with the recent discovery of a new species and new records of orchids from peninsular Thailand, especially in the Nakorn Si Thammarat mountain range (e.g. Ormerod et al. 2012; Tetsana et al. 2014; Chantanaorrapint and Chantanaorrapint 2016; Chantanaorrapint et al. 2017) it is clear that peninsular Thailand is an important region for orchid diversity and that further new species records can be expected to be found from many unexplored areas in this part of the country.

There are now three species of Corybas known from Thailand. A key to distinguish these is given below.

Key to the species of Corybas in Thailand

1 Lateral sepals and petals free at base; spurs inconspicuous, broad and poorly developed C. geminigibbus
– Lateral sepals adnate laterally to the connate petals at base; spurs well-developed, conical, slightly oblique to divergent 2
2 Flowers pink, dorsal sepal as long as the lateral sepals, acute at apex; central portion of labellum bearing a callus C. ecarinatus
– Flowers purplish, dorsal sepal shorter than the lateral sepals, rounded at apex; central portion of labellum hairy without a callus C. papillatus

Acknowledgements

We would like to thank the staff of BKF, C. Hemrat and S. Jirakorn for their help in the field; and A. Schuiteman (K) for his useful comments relating to this new species. We would also like to thank anonymous reviewers for their valuable comments and suggestions to improve the manuscript. This work was supported by the Prince of Songkla University annual government expenditure under the Plant Genetic Conservation Project Year 2018 (no. SCI600107S) under the Royal initiative of Her Royal Highness Princess Maha Chakri Sirindhorn.

References

  • Anker K, Seidenfaden G (2001) Corybas ecarinatus sp. nov. (Orchidaceae) from Thailand. Nordic Journal of Botany 20(5): 557–559.
  • Chantanaorrapint S, Puangpairote T, Sae Wai J, Chantanaorrapint A (2017) Note on Goodyera lanceolata (Orchidaceae), a mysterious orchid species. Polish Botanical Journal 62(2): 229–232. https://doi.org/10.1515/pbj-2017-0015
  • Dransfield J, Comber JB, Smith G (1986) A synopsis of Corybas (Orchidaceae) in West Malesia and Asia. Kew Bulletin 41(3): 575–613. https://doi.org/10.2307/4103118
  • Go R, Ching TM, Nuruddin AA, Abdullah JO, Jin NY, Nordin FA, Eng KH, Nulit R (2015) Extinction risks and conservation status of Corybas (Orchidaceae; Orchidoideae; Diurideae) in Peninsular Malaysia. Phytotaxa 233(3): 273–28. https://doi.org/10.11646/phytotaxa.233.3.4
  • Ormerod P, Chantanaorrapint S, Kurzweil H (2012) Cephalantheropsis longipes (Orchidaceae), a new record for Peninsular Thailand. Thai Forest Bulletin (Botany) 40: 118–120.
  • Pedersen HÆ (2011) Corybas. In: Santisuk T, Larsen K (Eds) Flora of Thailand Vol. 12(1). The Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Bangkok, Thailand, 42–44.
  • Pridgeon AM, Cribb PJ, Chase MW, Rasmussen FN (2001) Genera Orchidacearum Vol. 2: Orchidoideae (Part one). Oxford University Press, Oxford.
  • Tandang DN, Bustamante RA, Ferreras U, Hadsall AS, Pym-Lyon S, Robinson AS (2020) Corybas circinatus (Orchidaceae), a new species from Palawan, the Philippines. Phytotaxa 446: 135–140. https://doi.org/10.11646/phytotaxa.446.2.7