Oreocharis longituba 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 : 97-101

Oreocharis longituba W.H.Chen, Q.H.Nguyen & Y.M.Shui sp. nov. Figs 2A-H , 4

Diagnosis.

This new species is similar to O. hirsuta Barnett from Thailand, but differs from it in its pubescent petioles (vs. hirsute), (sub)orbicular leaves (vs. narrowly ovate or lanceolate), rounded leaf apex (vs. acute to short acuminate), crenate leaf margin (vs. bi-serrate), narrowly infundibuliform corolla tube (vs. tubular), anthers coherent in pairs (vs. free) and glabrous filaments (vs. hirsute).

Type.

VIETNAM. Lao Cai, Sa Pa distr., Ta Phin cave, in secondary forests, 22°20'54.48"N, 103°46'12.98"E, 1879 m elevation, 30 October 2012, type specimens from plants cultivated in an experimental greenhouse at Kunming Botanic Garden, 7 September, 2013, Y.M. Shui et al. B2013-551 (holotype, KUN!; isotype, Herbarium of the Centre for Plant Conservation, Vietnam Union of Science and Technology Associations, Hanoi!).

Perennial herb. Leaves in basal rosette. Petiole 4-7 cm long, densely long pubescent; leaf blade (sub)orbicular, 3-9 × 2.4-8.9 cm, adaxially sparsely hirsute, abaxially pubescent, more densely so on venation, base cordate, apex rounded, margin crenate; lateral veins 5-6 pairs, adaxially depressed, abaxially prominent. Inflorescences axillary, 1-2-flowered. Peduncles 8-11 cm long, densely white villous; bracts 2, linear-lanceolate, 5-22 × 0.7-1.2 mm, adaxially subglabrous, abaxially pubescent; pedicel 1.8-2 cm, pubescent. Calyx 5-parted almost from base, segments linear-lanceolate, 8-15 × 1-4 mm, margin dentate, adaxially glabrous, abaxially white hispid. Corolla yellow, bilabiate, 3-3.5 cm long, inside pubescent, outside white glandular; tube narrowly infundibuliform, 2-2.5 cm long, 3-3.5 mm in diam. at base and 6-7 mm in diam. at throat; adaxial lip 6.5-7 mm long, 2-lobed, lobes suborbicular, 3.3-3.5 × 3.5-3.8 mm, apex obtuse; abaxial lip 3-lobed, lobes sub-oblong, almost equal, 8-10 × 6-8 mm, apex obtuse. Stamens 4, anthers coherent in two pairs, adaxial stamens 5-7 mm long, adnate to corolla tube 1.2-1.5 mm from base, abaxial stamens 7.5-8 mm long, adnate to corolla tube 1-1.2 mm from base; filaments glabrous; anthers round, basifixed, dehiscing longitudinally; staminode 1, 2.5-3 mm long, adnate to corolla tube 6-7 mm from base. Pistil 1.7-2.1 cm long when mature; ovary cylindrical, 1.2-1.4 cm long, glabrous, 2-locular; style 5-7 mm long, white pubescent; stigma 1, flattened with a central depression. Disc cylindrical, yellowish, 2.8-3 mm high, margin shallowly dentate. Capsule straight, cylindrical, 3-5 cm long. Seeds oblong, 1.1-1.2 mm long.

Distribution, habitat and phenology.

This new species is also endemic to Sa Pa, northern Vietnam and grows widely scattered on wet ground along road sides or along streams in evergreen broad-leaved forests, at an elevation of 1700-1890 m. Flowering from August to September and fruiting from September to October.

Etymology.

The species epithet refers to the unusually long length of the corolla tube in Oreocharis .

Conservation status.

Endangered EN B2ab (iii), following IUCN (2012) guidelines. This is based on an EOO of <35 km2, being known from fewer than five populations and with disturbed locality.

Additional specimens examined.

VIETNAM. Lao Cai, Sa Pa distr., Kuoang Village, 22°28'43.66"N, 103°47'41.5"E, 1700 m elevation, growing on humus soil in wet and shady places, 11 September 2005, X. P. Vu, D. H. Duong, V. D. Nguyen, Q. B. Nguyen, T.D.Nguyen, R. de Kok, G. Bramley, G. Challen, M. Vorontsova HNK 58 (K!); Sa Pa, Ta Phin cave , in secondary forests, 22°20'54.48"N, 103°46'12.98"E, 1879 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 CK670 (KUN!, Herbarium of the Centre for Plant Conservation, Vietnam Union of Science and Technology Associations, Hanoi!) ; Sapa distr., the path to Fanxipan from Ton Station , 22°20'01"E, 103°46'47.8"E, 2000 m elevation, 10 August 2007, in fruit, N. V. Du, P. Wharton & B. Wynn-Jones 10 (K!); Tonkin, route de Chapa à la garderie du Col de Lo Qui Ho , 1800 m elevation, September 1929, in flower, P. A. Pételot 5177 (P: P03934211!; P04079324!; P03511246!); Col de Lo Qui Ho , elev. 2000 m, August 1933, in flower, P. A. Pételot 7247 (P: P03934227); Col de Lo Qui Ho , elev. 1900, 16 August 1926, in flower, Poilane 12965 (P: P04079331) .

Notes.

A previous collection of this species, X.P. Vu et al. HNK 58, K!, had been identified as Oreocharis hirsuta , a species from Thailand that demarcates the southern most distribution of the genus ( Barnett 1961; Möller et al. 2011). When comparing the specimens studied here with type material and recent collections of O. hirsuta in the herbaria of the Royal Botanic Gardens, Kew (K) and the Royal Botanic Garden Edinburgh (E), it was found that they can be morphologically differentiated (Table 2 ; Figs 2I-L ). Earlier collections by Pételot and Poilane in Vietnam and deposited in the Muséum National d’Histoire Naturelle in Paris (P), remained unnamed until now. These collections were made near Chapa at Lo Qui Ho, a station on the slopes near the summit of Fan Si Pan).

With its long corolla tube up to 2.5 cm, O. longituba has the longest tube amongst the yellow flowered species with infundibuliform corollas in Oreocharis . It is also the only species with coherent anthers amongst species in the previous, narrower concept of Oreocharis . In the current wider delimitation of Oreocharis , the corolla tube is more similar in shape, though not in size, to those species previously placed in Ancylostemon Craib and Paraisometrum Wang ( Wang et al. 1990, 1998; Weitzman et al. 1997; Chen et al. 2014).

Figures

Figure 2. Oreocharis longituba W. H. Chen, Q. H. Nguyen & Y. M. Shui, sp. nov. (A-H) and its most similar species, Oreocharis hirsuta Barnett (I-L) A Habitat B Mature plant C Abaxial leaf surface D, E Front view of flower F Pistil with immature stigma, disc and calyx G Lateral view of flower H Opened corolla I Mature plant J Flower and fruits K Front view of flowers L Side view of flowers. Scale bars: A, I = 5 cm, D-H = 1 cm; J, K, L = 2 cm. A-H photographs by Yu-Min Shui, I-L by Preecha Karaket of Middleton et al. 4550.

Figure 4. Oreocharis longituba W. H. Chen, Q. H. Nguyen & Y. M. Shui, sp. nov. (all drawings based on the holotype Y. M. Shui et al. B 2013 - 551 in KUN, drawn by J. X. Liu). A Habit B Abaxial leaf surface C Opening flower from below showing the inflated part near the distal end of the corolla tube D Open flower from above E Opened corolla showing two pairs of stamens F Pistil (immature at male stage), disc and calyx G Front view of flower.