Oreocharis ninglangensis W.H.Chen & Y.M.Shui, 2016

Chen, Wen-Hong, Chen, Run-Zheng, Möller, Michael, Wen, Kai & Shui, Yu-Min, 2016, Oreocharis ninglangensis, a showy new species of Gesneriaceae from northwestern Yunnan in China, Phytotaxa 261 (3), pp. 282-286 : 282-285

Oreocharis ninglangensis W.H.Chen & Y.M.Shui , sp. nova ( Fig. 1 )

Type: — China. Yunnan Province, Ninglang County, Lugu Lake, on cliff in ravine, 27°39 ′ N, 100°46 ′ E, elevation 2700 m, 19. Aug. 2010, in flower, Y. M.Shui et al. N 699 (holotype, KUN 0980887! isotype, PE!).

Diagnosis: O. ninglangensis is most similar to O. delavayi Franchet (1888: 715) but can easily be distinguished from this species by the presence of 10 red stripes at the roof of the corolla mouth, by the light yellow corolla color and by the finely bullate leaf surface in the later.

Herbs perennial, acaulescent. Leaves in basal rosette. Petioles 2–4.5 cm long, brown strigose; leaf blades ovate oblong, 1.5–2.8 × 0.9–1.5 cm, both sides with brown pubescence, base slightly cordate, margins crenate with conspicuous brown pubescence; lateral veins 4–5 pairs on each side of midrib, adaxially inconspicuous, abaxially conspicuous. Inflorescences axillary, 1(–2)-flowered. Peduncles 3.5–5.5 cm long, with reddish brown glandular pubescence; bracts, linear, ca. 1 × 0.5 mm. Calyx 5-sect almost from base, linear lanceolate, ca. 2 × 1 mm, entire, with reddish brown glandular pubescence. Corolla yellow, bilabiate, inside glabrous, outside sparsely glandular pubescent; tube narrowly funnelform, ca. 0.7 cm long, 0.3–0.4 cm in diameter, slightly widening at mouth, not distensible on tube base; adaxial lip 2-lobed, lobes broadly ovate, imbricate, ca. 0.4 cm in diameter, apex obtuse; abaxial lip 3-lobed, lobes ovate, imbricate, middle lobe ca. 1.1 cm in diam., lateral lobes, ca. 0.9 cm in diam., apex subrounded. Stamens 4, exserted, filaments straight, white glandular, adaxial stamens ca. 1.3 cm long, adnate to corolla tube ca. 1 mm from base, abaxial ca. 1.2 cm long, adnate to corolla tube ca. 1.5 mm from base; anthers hippocrepiform, basifixed, dehiscing longitudinally; staminoide 1, ca. 3 mm long, adnate to adaxial side of corolla tube ca. 1 mm from base. Pistil included at beginning of flowering, later extended, as long as the stamens, ca. 1.3 cm long, glabrous; ovary narrowly oblong, ca. 9mm, 2-loculed; stigma 1, discal; disc ringlike, ca. 1 mm high, slightly crenate. Capsule straight, oblong, ca. 2.5 cm long, dehiscing loculicidally, more predominant on one side initially. Seeds oblong, ca. 1 mm long.

Additional specimens examined: China. Yunnan Province, Ninglang County, Lugu Lake, on cliff in ravine, 27°39 ′ N, 100°46 ′ E, elevation 2700 m, 25 Jun. 2010, in flower, Y.M.Shui et al. N077 (H-Dian-Ninglang-Z-077) (KUN). Same location, 27 Aug. 2014, in flower, L.Cai et al. B2014-273 (KUN).

Ecology and distribution: The new species is endemic to Ninglang County, northwestern Yunnan Province bordering Sichuan Province, China.

Phenology: Flowering in August to September, and fruiting in September to November.

Conservation assessment: This new species grows on shady damp moss-covered valley cliffs, at an elevation of 2600–2800 m and is presently only known to occur in three populations near Lugu lake, Ninglang county, Yunnan Province. Two are in the Axia valley, an abandoned tourist attraction site near Lugu lake, and the third is on hill cliffs above the Axia tunnel. The largest population in Axia valley has around 150 mature and about 200 immature plants, with an area of occupancy of around 400 m 2. The other two populations in Axia valley and above the Axia tunnel have 30–50 mature plants with an area of occupancy of around 30 m 2. The species is provisionally assessed as “Critically Endangered” [CR B2a] following IUCN Red List Categories and Criteria ( IUCN 2012), because of the restricted range and low number of mature plants. Recent observations for all three populations from 2010 to 2014 indicated a steady decline in population size, with droughts and anthropogenic interference being two main threats to the habitat.

Affinities: The genus Oreocharis was recently redefined which greatly widened its morphological circumscription ( Möller et al. 2011). The new species described here has several features that fit well the original definition of the genus, notably the thick straight filaments with non-coherent anthers, and can thus comfortably be placed here. The exserted stamens are reminiscent of species in the previous genus Tremacron Craib (1918: 217) , though the abaxial corolla lobes are much smaller in this genus ( Wang et al. 1998). However, because of the close phylogenetic relationship of the two genera and overlapping morphological characters Tremacron was sunk into Oreocharis ( Möller et al. 2011) .

Like other members of the Oreocharis , such as O. mileense W.T.Wang in Weitzman et al. (1998: 434) ( Chen 2013) and O. delavayi , O. ninglangensis is protrandrous showing a distinct male and female stage. During anthesis, the abaxial pair of anthers mature first, while the adaxial ones are still immature and their filaments quite short and only develop later their full length. At the time of flower opening, the pistil is also still greatly underdeveloped and remains so throughout the male stage ( Fig. 1C ) and only reaches its full length towards the later stages of anthesis ( Fig. 1G ). Only at this stage, the stigma is fully developed and shows its typical features in size and shape, pointing to the critical importance of detailed observations to fully and accurately describe species in this genus.

The new species has one of the smallest leaves within the genus and with their crenate margin resemble those of O. parva (K.Y.Pan 1988: 453) Mich.Möller & W.H.Chen (2014: 201) and O. delavayi . Though the flowers of the former are purple. Florally, O. ninglangensis resembles most closely O. delavayi , most notably in shape, but can be easily distinguished by its absence of the red stripes at the roof of the corolla mouth and the bullate leaf surface with depressed and reticulate veinlets of the later, making it an attractive addition to the genus Oreocharis .

Figures

FIGURE 1. Oreocharis ninglangensis W.H.Chen & Y.M.Shui, sp. nov. (A–D and I: based on the holotype) and O. delavayi (E–H). A. Habitat; B. Face view of corolla (abaxial stamens mature first at the beginning of anthesis, male stage); C. Opened flower showing pistil and stamens (before anthesis); D. Top view of flower with sepals (at male atage); E. Face view of corolla (at later stage of anthesis with both pairs of stamens mature, male stage); F. Opened flower showing pistil and stamens (just before stigma receptivity, female stage); G. Lateral view of flower with sepals (at stigma receptivity, female stage); H. Adaxial view of a leaf (showing its bullate leaf surface with depressed and reticulate veinlets); I. Adaxial view of a leaf (showing its flat leaf surface with inconspicuous veinlets). Scale bars:A=5cm, B=5 mm, C=5 mm, D=5 mm, E=5 mm; F=5 mm, G=5 mm, H=1 cm, I=1 cm (all photographs by Yu-Min Shui).