Oreocharis grandiflora W.H.Chen, Q.H.Nguyen & Y.M.Shui, 2018

Chen, Wen Hong, Nguyen, Quang Hieu, Chen, Run Zheng, Nguyen, Tien Hiep, Nguyen, Sinh Khang, Nguyen, Van Tap, Moeller, Michael, Middleton, David J. & Shui, Yu-Min, 2018, Two new species of Oreocharis (Gesneriaceae) from Fan Si Pan, the highest mountain in Vietnam, PhytoKeys 94, pp. 95-106 : 96-97

Oreocharis grandiflora W.H.Chen, Q.H.Nguyen & Y.M.Shui sp. nov. Figs 1A-F , 3

Diagnosis.

This new species is similar to O. flavida in the orange colour of the corolla, but differs from the latter by its much larger corolla (3.3-3.6 cm long vs. 1.5-1.7 cm), the shape of the corolla tube (infundibuliform vs. campanulate) and the reniform anthers which are coherent in two pairs (vs. horseshoe-shaped and not coherent). The two species further differ by the narrowly oblong or elliptic leaf blades in the new taxon (vs. ovate-elliptic to broadly ovate), cuneate leaf base (vs. cordate to rounded), the glandular villous indumentum on the outer surface of the calyx lobes (vs. eglandular villous).

Type.

VIETNAM. Lao Cai, Sa Pa distr., Ta Phin cave, in secondary forests, on cliffs nearby waterfalls, 22°20'43.66"N, 103°46'30.48"E, 2017 m elevation, 30 October 2012, type specimen from a plant cultivated in an experimental greenhouse at Kunming Botanic Garden, 7 September 2013, Y.M. Shui et al. B2013-550 (holotype, KUN!; isotype: Herbarium of the Centre for Plant Conservation, Vietnam Union of Science and Technology Associations, Hanoi!).

Perennial herbs. Leaves in basal rosette. Petiole 2.2-2.6 cm long, with dense white glandular hairs; leaf blade coriaceous, narrowly oblong or elliptic, 4-6 × 1.8-3.5 cm, adaxially and abaxially covered by white glandular hairs, more densely on veins, base narrowly cuneate, apex acute, margin crenate; lateral veins 4-5 on each side of the midrib, adaxially depressed, abaxially prominent. Inflorescences axillary, 1-4-flowered. Peduncles 6-12 cm long, with white glandular hairs; bracts 2, lanceolate, 5.6-6 × 1.1-1.2 mm, abaxially covered by white glandular hairs. Pedicel 1.5-1.8 cm long. Calyx 5-lobed from base, lobes equal, linear-lanceolate, 7-8 × 1.1-1.2 mm, entire, adaxially glabrous, abaxially with white glandular hairs. Corolla deep orange, slightly bilabiate, 3.3-3.6 cm long, inside pubescent, outside with white glandular short hairs; tube infundibuliform, 2-2.2 cm long, 2.7-3 mm in diam. at base and 8-9 mm in diam. at throat; adaxial lip 2-lobed, lobes suborbicular, 8.5-9 × 11-12 mm, apex obtuse; abaxial lip 3-lobed, lobes suborbicular, slightly equal, 13-14 × 8-9 mm, apex more or less rounded. Stamens 4, anthers coherent in two pairs, filaments adnate to base of corolla tube, adaxial stamens 2-2.2 cm long, abaxial stamens 2.6-2.8 cm long; filaments with white glandular hairs; anthers reniform, basifixed; staminode 1, adnate to base of corolla tube, 5-6 mm long. Pistil 3.1-3.5 cm long when mature; ovary cylindrical, 2-2.2 cm long, glabrous; style 1-1.3 cm long, with white glandular hairs; stigma 1, flattened with central depression. Disc ringlike, yellowish, 2-3 mm high. Capsule straight, cylindrical, 2.1-2.5 cm long.

Distribution, habitat and phenology.

This new species is endemic to Sa Pa, northern Vietnam and grows densely on cliffs by waterfalls along deep valleys in evergreen broad-leaved forests, at an elevation of around 1800-2010 m. Flowering from August to October and fruiting from September to October.

Etymology.

The species epithet refers to the large size of the flowers. Based on the authors’ observation and other relevant publications ( Wang et al. 1990, 1998), the new species has one of the largest flowers in Oreocharis .

Conservation status.

This new species appears to be restricted to a very moist habitat in Sa Pa, Lao Cai Province, northern Vietnam. It grows on several steep cliffs at 1800-2100 m elevation by waterfalls with flowing water throughout the year (Fig. 1A ). It flowers during the rainy season (September to October), during which the locality is inaccessible. This is likely the reason why it had not previously been discovered. It is naturally protected by its inaccessible habitat on the cliffs. According to our observations in the field, the two known populations harbour about 100 mature individuals in each. In fact, there are many waterfalls at this altitudinal range and, thus, the real number of populations and individuals may be higher. Nevertheless, its unusually humid habitat might be affected by climate change-induced droughts. Overall however, the species has been classified as "Data Deficient" [DD] following IUCN Red List Categories and Criteria ( IUCN 2012).

Additional specimens examined.

VIETNAM. Lao Cai, Sa Pa distr., Ta Phin cave, in secondary forests, 22°20'43.66"N, 103°46'30.48"E, 2017 m elevation, 30 October 2012, in fruit, Q.H.Nguyen, T.H.Nguyen, Y. M. Shui, Y. K. Sima, S. X. Yang, Z. Zhou, J. Liu CK687 (KUN!, Herbarium of the Centre for Plant Conservation, Vietnam Union of Science and Technology Associations, Hanoi!).

Notes.

This new species resembles Oreocharis flavida , but differs in the characters in Table 1 (see also Fig. 1 ). Additionally, the corolla size range is larger than any other species in the former delimitation of Oreocharis . In size and shape, the corolla of the new species resembles that of Oreocharis ronganensis (K.Y. Pan) Mich. Möller & A. Weber (formerly Ancylostemon ronganensis K.Y. Pan), but in the latter the corolla is pink, not deep orange. This is a rare colour in Oreocharis s.l., since only about six of the>106 species have a corolla of such an intensely deep orange colour.

Figures

Figure 1. Oreocharis grandiflora W. H. Chen, Q. H. Nguyen & Y. M. Shui, sp. nov. (A-F) and O. flavida Merr. (G-I) A Habitat (red arrows indicate position of plants in the field) B Mature plant C Abaxial leaf surface D Front view of flower E Lateral view of flower F Opened corolla, pistil, disc and calyx G Plant H Inflorescence and open flowers I Dissected flower, showing corolla with free anthers, pistil, disc and calyx. Scale bars: A, C-F = 1 cm; B, G = 2 cm; H, I = 5 mm. All photographs by Yu-Min Shui.

Figure 3. Oreocharis grandiflora W. H. Chen, Q. H. Nguyen & Y. M. Shui, sp. nov. (all drawings based on the holotype Y. M. Shui et al. B 2013 - 550 in KUN, drawn by Y. F. Shui) A Habit B Opened corolla showing corolla lobes and two pairs of stamens C pistil at stigma receptivity and calyx.