Assistant Professor Dr Wilawan Promprom and Assistant Professor Dr Wannachai Chatan, SCIMSU researchers from the Department of Biology at Mahasarakham University, discovered Bauhinia thailandica, a new species in the tribe Cercideae, in Thailand.

Abstract: Bauhinia thailandica, a new species in the tribe Cercideae, subfamily Cercidoideae in the Leguminosae collected from the Northeast of Thailand, is described and illustrated. It is similar to B. acuminata and B. hirsuta but easily distinguished by their habits, indumentum, floral bud, hypanthium, petal and bud. The distinguishing characters of these three species are discussed. A key to Bauhinia species in Thailand is included.

Bauhinia thailandica Chatan & Promprom, sp. nov.

Type: —THAILAND. Sakon Nakhon Province: Phu Pha Yon National Park, 300–600 m elev., 16°55’50.6” N 104°12’28.2” E, May 11th, 2018, W. Chatan 2664 (holotype: BKF! isotype: BK! K!).

Diagnosis: —The corolla colour, number of fertile stamen, and bud characteristic of Bauhinia thailandica suggest a close relationship to B. acuminata and B. hirsuta, but it differs from the two species by the following characters: its smaller stature (40–140 cm high), patent hairs on branch, petiole, calyx, hypanthium and floral bud; smaller floral bud (2.3–2.5 cm); smaller petal size (24–28 × 6–13 mm); pod with narrower suture (2.0–2.5 mm), indistinct raised suture and slightly blunt-edged.

Bauhinia thailandica Chatan & Promprom, sp. nov. A. habit; B. branch with leaves and inflorescence; C. inflorescence (lateral view); D. pod; E. pod (different view from D.); F. floral bud. Photographed by Wannachai Chatan.
Line drawing Bauhinia thailandica Chatan & Promprom, sp. nov. A. branch with leaves and inflorescence; B. floral bud; C. flower; D. calyx; E. calyx (different view from D.); F. five petals; G. androecium (expanded); H. pistil of bisexual flower; I. pistil of staminate flower J. pod; K. seeds. Drawn by Wannachai Chatan from the type specimen (W. Chatan 2664).

Flowering and fruiting: —Flowering in May–July and fruiting in July–August.

Distribution: —The new species is an endemic to Thailand and known from only the type locality, Phu Pha Yon National Park, Sakon Nakhon Province, Northeastern Thailand.

Ecology: —This new species grows in open areas in dry deciduous forest and near roadsides in dry evergreen forest, at an elevation of 300–600 m.

Vernacular name: —Siew Phum. (เสี้ยวพุ่ม)

Etymology: —The specific epithet of B. thailandica refers to the type locality of the new species and it being endemic to Thailand. Preliminary conservation status: —Bauhinia thailandica is known only from Phu Pha Yon Nation Park, Sakon Nakhon Province, and its estimated number of mature plants is less than 250 individuals. Therefore, it should be considered as “Endangered (EN)” according to the IUCN criteria D (IUCN 2017).

Chatan, W. and Promprom, W. 2018. New species of Bauhinia (Cercidoideae: Leguminosae) from Thailand. Phytotaxa 385 (1): 043–047.