Begonia mollissima Y.M.Shui, H.Q.Nguyen & W.H.Chen, 2018

Chen, Wen-Hong, Radbouchoom, Sirilak, Nguyen, Hieu Quang, Nguyen, Hiep Tien, Nguyen 4, Khang Sinh & Shui, Yu-Min, 2018, Seven new species of Begonia (Begoniaceae) in Northern Vietnam and Southern China, PhytoKeys 94, pp. 65-85 : 73-75

Begonia mollissima Y.M.Shui, H.Q.Nguyen & W.H.Chen sp. nov. Fig. 7

Begonia sect. Coelocentrum Irmsch.

Remarks.

The new species is similar to Begonia guangxiensis T.C. Ku in the dense white villous hairs on the whole plants, differs from the latter in the shorter hairs of plants (2.1-2.4 mm vs. 3.4-4.0 mm), its one obtuse leaf lobe (vs. 3-4 acute leaf lobes in B. Begonia guangxiensis ), subequal three wings of the fruit (vs. unequal three wings), narrowly semi-lunar major wings (vs. broadly square major wings).

Type.

VIETNAM. Bac Kan Province, Cho Ra county, Ba Be National Park , 22°24'56"N, 105°37'48"E, 235 m a.s.l., 18 April 2016, Y.M. Shui, W.H. Chen, C. Liu, H.Q. Nguyen, H.T. Nguyen, N.Q. Chuong CK1183 (holotype, KUN!; isotype, CPC!) .

Herb, rhizomatous.

Rhizome, densely white villous, 2-3 cm long, 0.7-1 cm in diam. Stipule green, 1.5-2 × 1-1.5 cm, widely ovate, apex acute to obtuse, margin ciliate. Leaves: petiole erect, densely white villous, 6-13 cm long, 1-3 mm in diam.; blade green, asymmetric, widely ovate, 8.5-18 × 7-12 cm, rugose, usually with one obtuse lobe; base cordate, apex acuminate or acute, margin slightly denticulate, ciliate; adaxially green, densely tubercular-based setose, abaxially pale green, reddish when young, densely villous on veins; venation palmate, 5-6 primary veins, 2 or 3 secondary veins brunching dichotomous, tertiary veins reticulate. Inflorescence: dichasial cyme, peduncle 12-15 cm long, villous; bracts not seen. Staminate flower: pedicels 0.5-1 cm long; tepals 4; outer tepals 2, broadly ovate, 7-11 × 6-8 mm, apex rounded to acute, margin entire sometimes serrate and ciliate; inner tepals 2, oblanceolate, 5-7 × 1.8-2 mm, apex obtuse to acute, margin entire; androecium actinomorphic, stamens numerous; filaments longer than anthers, slightly fused at base; anthers yellow, 1-1.2 mm long, shorter than filaments, with two longitudinal slits. Pistillate flower: pedicel 1.2-2 cm long; tepals 2, white or pinkish, widely obovate to orbicular, 0.5-1 × 0.5-1 cm, apex acute, margin entire; styles 2-3, free; stigmas bilobed with twisted bands; ovary green or pinkish, trigonous ellipsoid, 1-1.5 cm long, 0.5-1 cm in diam. (wings excluded), white or red villous, 1-loculed; placentation parietal, placentae 3, 2-branched. Capsule pale green to pink, trigonous-ellipsoid, 1-1.5 cm long, 0.5-1 cm in diam. (wings excluded), villous, brownish when dried, 3-winged unequally; abaxial wing lunate, 0.9-1.2 × 0.3-0.7 mm; lateral wings lunate, 0.9-1.2 × 0.2-0.5 cm. Seeds oblong, ca. 0.2 mm long.

Phenology.

Flowering in March-May, fruiting in April-June.

Etymology.

The epithet refers to the dense villous trichomes of the new species.

Habitat.

The species only grows on cliffs in limestone forests.

Distribution.

The species occurs exclusively in Ba Be National Park (Cho Ra county) of Bac Kan Province in Vietnam.

Note.

In Begonia sect. Coelocentrum , the new species is similar as Begonia guangxiensis in the dense hairy habit, mainly differing in the dense tubercular-based pubes on the abaxial surface of leaves (vs. villous trichomes in the latter species) and subequal wings (vs. unequal) ( Wu and Ku 1997; Shui and Chen 2017). It is also similar as B. calciphila C.-I Peng in the shape and trichomes of leaves, but differs in 0.5-1.2 cm long stout inter-nodes (vs. 1.5-4.5 cm long slender inter-nodes) and hairy flowers and fruits (vs. glabrous in the latter species) ( Peng et al. 2015b). In Bac Kan Province, Vietnam, there are four new species already described, viz. B. regosula Aver., B. babeana Aver. & H.Q. Nguyen ( Averyanov and Nguyen 2012) and two more new species described in this paper.

Figures

Figure 7. Begonia mollissima Y. M. Shui, H. Q. Nguyen & W. H. Chen A Habitat B Plant C View of adaxial leaf D Close-up of adaxial leaf E View of abaxial leaf F Close-up of abaxial leaf G Young leaf adaxially H Young leaf adaxially I Petiole J Stipule, adaxial view and abaxial view K Inflorescence L Staminate flower, face view, side view and dorsal view M Pistillate flower, face view, side view and dorsal view N Fruit, side view O Close-up of ovary cross section P Serial cross sections of ovary. (All photographs by Y. M. Shui).