Friday, July 13, 2018

[Botany • 2018] Begonia hinnamnoensis & B. khammouanensis • Two New Species of Begonia L. (Begoniaceae) from central Laos


ສົ້ມກຸ້ງຄັນຄາກ Begonia hinnamnoensis Souvann. & Lanors. &
ສົ້ມກຸ້ງໃບບົວ Begonia khammouanensis Souvann. & Lamxay,

in Souvannakhoummane, Lanorsavanh & Lamxay, 2018

Abstract
Two new species of Begonia are described and illustrated from Hin Nam No National Protected Area in the Khammouan Province, Central Laos. Begonia hinnamnoensis Souvann. & Lanors. and Begonia khammouanensis Souvann. & Lamxay, both belonging to Begonia sect. Diploclinium (Lindl.) A. DC. The two new species are endemic to the Khammouan limestone karst. The provisional IUCN status of both new species is here assessed as ‘Vulnerable’.

Keyword: Begonia hinnamnoensis, Begonia khammouanensis, Begoniaceae, Limestone flora, Laos, Taxonomy



Fig. 1. Begonia hinnamnoensis Souvann. & Lanors.
 A, Habit in nature; B, habit; C, inflorescences (bud); D. staminate flowers; E, pistillate flowers. (A & E photo by K. Souvannakhoummane; B-D photo by S. Lanorsavanh, all from Lamxay et al. HNN 227).
  
Begonia hinnamnoensis Souvann. & Lanors., sp. nov. 
ສົ້ມກຸ້ງຄັນຄາກ | Som Koung Khan Khak [Bufo begonia]
Sect. Diploclinium

Differs from the allied Begonia gesneriifolia Aver. in having a denser indumentum over all vegetative parts and fruit wings narrowly triangular (B. gesneriifolia has short scurfy hairs, sub-glabrous petioles, glabrous leaf lamina, inflorescenceand flowers, and fruit wings distinctly larger). Also differs from Begonia cladotricha M. Hughes in having a stout rhizome, upper surface of lamina bullate between veins giving a rugose appearance and pistillate flowers smaller fruit wings (B. cladotricha has tuberous rhizome, upper surface of lamina not bullate between veins and pistillate flowers larger fruit wings). 
− Type: Laos, Khammouan province, Boualapha district, Hin Nam No National Protected Area, ..., 240 m, 9 October 2017, Lamxay et al. HNN 227 (holo HNL, iso FOF, E, SING).  

Distribution. Endemic to Khammouan province, Boualapha district, Hin Nam No National Protected Area, only know from type locality. 

Habitat and ecology. Occurring on limestone rock crevices in seasonally dry evergreen forest at 240 m elevation. Flowering September to October; fruiting October to January. 


Notes. Begonia hinnamnoensis is closely allied with B. cladotricha and B. gesneriifolia, as shown by characters of reniform lamina and pistillate flowers with 5-tepals. The basally-branched hair type of this species is the same as in B. cladotricha (Hughes, 2008b). The specific epithet hinnamnoensis refers to the type locality


Fig. 3. Begonia khammouanensis Souvann. & Lamxay,
 A, habit in nature; B, habit; C, upper part of inflorescences; D. staminate flowers; E, pistillate flowers. A, C, E photo by K. Souvannakhoummane; B, D photo by S. Lanorsavanh from Lamxay et al. HNN 138.

Begonia khammouanensis Souvann. & Lamxay, sp. nov. 
ສົ້ມກຸ້ງໃບບົວ |  Som Koung Bai Boua [Lotus leaf begonia] 
Sect. Diploclinium

A distinct species, closest to Begonia crassula Aver. in having succulent leaves, the same number of tepals in male and female flowers and bifid, axile placentae. It differs in being stemless (not succulent caulescent), and in having a symmetric reniform lamina, (not strongly asymmetric and narrowly ovate), and lanceolate and acuminate apex of tepals (not reniform and rounded apex of tepals).
− Type: Laos, Khammouan province, Boualapha district, Hin Nam No National Protected Area, ..., 259 m,, 10 October 2017, Lamxay et al. HNN 138 (holo HNL, iso FOF, E, SING). 

Distribution. Endemic to central Laos; Hin Nam No National Protected Area with three additional populations in Boualapha district, Khammouan province. 

Habitat and ecology. This species occurs on wet steep rocky slopes in limestone mixed deciduous forest and dry evergreen forest at 230-400 m elevation. Flowering September to October; fruiting October to January. 

Notes. This species is distinct in its glabrous and glossy symmetrical reniform lamina, and petioles and inflorescences with glandular hairs. The specific epithet khammouanensis refers to the type locality. 


Keooudone Souvannakhoummane, Soulivanh Lanorsavanh and Vichith Lamxay. 2018. Two New Species of Begonia L. (Begoniaceae) from central Laos. Taiwania. 63(3); 188-194.  DOI:  10.6165/tai.2018.63.188

    

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