Monday, January 15, 2018

[Botany • 2018] Thismia bokorensis • A New Species (Burmanniaceae) representing A New Generic Record for Cambodia [Flora of Bokor National Park VII]

Thismia bokorensis Suetsugu & Tsukaya

in Suetsugu, Tsukaya, Tagane, Chhang, Yukawa & Yahara, 2018.

The genus Thismia Griffith (1844: 221) of the tribe Thismieae, Burmanniaceae sensu APG IV (2016) or Thismiaceae of other authors, represents one of the most species-rich mycoheterotrophic genera and consists of more than 60 species (Jonker 1948, Merckx 2008). Considering that the majority of these species were collected only once (Jonker 1948), and that many new species have recently been discovered, especially from various Southeast Asian countries (e.g., Tsukaya & Okada 2012, Dančák et al. 2013, Nuraliev et al. 2014, 2015, Truong et al. 2014, Chantanaorrapint & Sridith 2015, Li & Bi 2013, Hroneš et al. 2015, Tsukaya et al. 2017, Suetsugu et al. 2017), many more undescribed species are probably still hidden in the tropical rain forests of Southeast Asia.

Here, we describe a new species, Thismia bokorensis Suetsugu & Tsukaya, discovered during a botanical survey in Bokor National Park, Cambodia, in 2013. This is the first record of the genus Thismia for Cambodia. The newly discovered specimen apparently belongs to the section Thismia (formerly Euthismia Schltr.) subsect. Brunonithismia Jonker (1938: 242), in having free and spreading inner perianths, larger inner perianth lobes, and vermiform, creeping roots. After a careful examination, the unknown plant was found to have a significantly different floral morphology from all the other known species.  

FIGURE 1. Thismia bokorensis from the type locality.
A–B. Flowers. C. Flowering plant.  

Thismia bokorensis Suetsugu & Tsukaya, sp. nov.

Type:— CAMBODIA. Kampot Province: Bokor National Park, evergreen forest near a stream, ... elev. 370 m, 10 Aug. 2013, Tagane, Fuse, Yokota, Zhang & Chhang 5857 (holotype: TNS, in the spirit collection).

 Thismia bokorensis is similar to Thismia tentaculata Larsen & Averyanov (2007: 16) of Vietnam and Hong Kong in having the lateral appendage of the connective that does not exceed the apical part of the connective, three-toothed apical margin of the connective, and the shorter light yellow tentacles in inner perianth lobes.

 Habitat and ecology:— Only one individual was found in the evergreen forest, near a stream, at an elevation of 370 m. The forest was dominated by Scaphium affine (Malvaceae), Diospyros schmidtii (Ebenaceae), Ardisia sanguinolenta (Primulaceae), Epiprinus siletianus (Euphorbiaceae), Mallotus subpeltatus (Euphorbiaceae), Knema lenta (Myristaceae), Syzygium siamense (Myrtaceae), and Prismatomeris tetrandra (Rubiaceae). The roots of the specimen above were tangled to an old seed of Ixonanthus reticulata (Ixonanthaceae). The flowering specimen was collected in August.

Kenji Suetsugu, Hirokazu Tsukaya, Shuichiro Tagane, Phourin Chhang, Tomohisa Yukawa and Tetsukazu Yahara. 2018.  Flora of Bokor National Park VII: Thismia bokorensis (Burmanniaceae), A New Species Representing A New Generic Record. Phytotaxa.  334(1); 65–69. DOI:  10.11646/phytotaxa.334.1.10

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