Sunday, February 27, 2022

[Botany • 2021] Begonia markiana (Begoniaceae, sect. Platycentrum) • A New Species from Lower Dibang Valley of Arunachal Pradesh, Northeast India



Begonia markiana Taram, Wahlsteen & D.Borah, 

in Taram, Wahlsteen & Borah, 2022. 

Abstract
The new species Begonia markiana is described and illustrated. It is similar to B. cathcartii but can easily be distinguished by a lamina with a dark central spot and a densely pilose upper surface in combination with a short dorsal capsule wing. A phylogenetic analysis based on three chloroplast regions placed the new species together with other continental species in section Platycentrum. Both morphology and molecular data suggest the new species as a member of the section Platycentrum.

Keyword: Begonia annulata, Begonia cathcartii, chloroplast DNA, ndhA, new species, ndhF-rpl32, phylogeny, Platycentrum


Begonia markiana Taram, Wahlsteen & D.Borah.
A. Habit. B. Stipule. C. Leaf. D & E. Male flowers. F & G. Female flowers. H. Inner tepal. I. Outer tepal. J. Dry capsule. K. Fresh capsule.
 All scale bars indicate 1 cm. From M. Taram & O. Taku 5442.

Begonia markiana Taram, Wahlsteen & D.Borah, sp. nov. 

Type: INDIA. Arunachal Pradesh, Lower Dibang Valley District, Mayodia, 2000 m, 09 September 2021, M. Taram & O.Taku 5442 (holotype: CAL; Isotype: CAL). 

Diagnosis. Begonia markiana is similar to B. cathcartii Hook.f. & Thomson (Fig. 3) but can easily be distinguished by the lamina with a dark central spot (versus unicolored) and the densely pilose upper surface (versus sparsely strigose), and a short dorsal capsule wing (circa 10 mm versus 15–24 mm).

Etymology: The species epithet honors Mark Hughes (UK) who is one of the leading scholars untangling the knots of the genus Begonia in the Old World and his contribution to the knowledge of the genus in northeast India, especially. 

Distribution and ecology: So far, B. markiana is only known from the Mayodia area in the Lower Dibang River District in Arunachal Pradesh, India. It grows by stream sides in large patches, hanging from vertical rocks.

Begonia cathcartii Hook.f. & Thomson
 in Arunachal Pradesh, India.
 

Momang Taram, Eric Wahlsteen and Dipankar Borah. 2022. Begonia markiana (Begoniaceae), A New Species from Lower Dibang Valley of Arunachal Pradesh, Northeast India. Taiwania. 67(2); 165‒170.