Oreocharis flavovirens Xin Hong, 2020

Qin, Wei-Hua, Ding, Dong-Dong, Li, Zhong-Lin, Gao, Yun-Feng, Li, Shu & Hong, Xin, 2020, Oreocharis flavovirens, a new species of Gesneriaceae from Southern Gansu Province, China, PhytoKeys 157, pp. 101-112 : 101

Oreocharis flavovirens Xin Hong sp. nov. Figures 1 , 2

Diagnosis.

Oreocharis flavovirens can be diagnosed as a new species from all others in the genus by the upturned corolla tube combined with its rare greenish-yellow colour.

Type.

CHINA. Gansu Province: Yuhe Provincial Nature Reserve, Longnan City, 33.08426°N, 105.27858°E, 1,193 m a.s.l., 5 September 2018, flowering, Xin Hong: HX18090510 (holotype: IBK; isotype: PE).

Description.

Perennial, rosette herbs. Leaves basal, spirally arranged, 4-20, petiolate; petioles terete, 1.4-4 cm long, ca. 2 mm in diameter, densely reddish-brown long woolly and white glandular hairy; leaf blades ovate to obovate or elliptic, 3-6 × 1.5-3 cm, bases cuneate, slightly unequal, margins crenate to lobulate, apices obtuse, papery, adaxially sparsely rust-brown villous hairy, green, abaxially densely brown villous along veins, pale green; midrib usually vivid when fresh, lateral veins 3-5 on each side of midrib, distinct, concave adaxially, prominent abaxially. Inflorescences cymes, axillary, 1-2(-3)-branched, 1-6(-10)-flowered; peduncles 4-10 cm long, pale green, densely white glandular hairy and sparsely brown pilose; pedicels 1-3(-5) cm long, with indumentum as on the peduncle. Bracts 2, ca. 3 × 1 mm, lanceolate, margins entire, green, glabrous inside, brown pilose and sparsely glandular hairy outside; bracteoles similar but smaller, ca. 1.5 × 0.5 mm. Calyx actinomorphic, 5- sect from base, segments oblong to linear-lanceolate, 2-3.5 × ca. 1.0 mm, green, glandular hairy outside and glabrous inside, margins entire, sometimes revolute when flowering. Corolla zygomorphic, ca. 2 cm long, greenish-yellow to greenish, lobes greenish, becoming white at tube base, outside densely glandular-pubescent, inside glabrous; tube cylindrical, dilated and slightly narrowing gradually ventricose from base to throat and constricted at the throat, ca. 15 mm long, ca. 3 mm in diameter at base and ca. 2 mm in diameter at the throat; limb slightly 2-lipped; adaxial lip rounded, 2.5-3 × ca. 3 mm, emarginate or rarely undivided, shorter than abaxial lip; abaxial lip 3-sect from above middle, lobes obovate to elliptic, apex rounded, central longer than laterals, 3 × 4-ca. 3 mm. Stamens 4, adnate to corolla 1-4 mm above base, included; filaments slender, the long two ca. 8 mm long, the short two ca. 6 mm long, sparsely glandular-pubescent, free, white to greenish; anthers yellow, basifixed, coherent in pairs, thecae divergent at base, oblong, ca. 0.5 mm long, 2-loculed, dehiscing longitudinally from arcuate slits, connective not projecting, glabrous; staminode 1, glabrous, 0.5-1.5 mm long, adnate to 1 mm above corolla tube base. Disc ring-like, 1-1.5 mm high, glabrous, entire or subentire, greenish-yellow. Pistil 1-1.2 cm; ovary narrowly oblong, 1-loculed, ca. 1 cm long; placentas 2, parietal, projecting inwards, 2-cleft, style 1-2 mm long, glabrous; stigma orbicular, emarginated, ca. 2 mm in diameter. Capsules oblong lanceolate to oblanceolate, straight, 2-4 cm long, dehiscing loculicidally to base; valves 2, glabrous. Seeds unknown.

Etymology.

The specific epithet is derived from its greenish-yellow corolla.

Distribution and habitat.

To date, Oreocharis flavovirens is only found at the type locality, Yuhe Provincial Nature Reserve, Gansu Province, which is located at the intersection of the Qinling Mountains and the Minshan Mountains. This species grows amongst moss on moist shady surfaces of stones near waterfalls, at an elevation of 950-1200 m a.s.l. The average temperature is 21°C, the average annual precipitation has been calculated as ca. 780 mm. The forest is a subtropical evergreen broad-leaved forest.

Notes.

As is known, Oreocharis Benth. is a genus (more than 120 species) in the angiosperm family Gesneriaceae , which are mainly distributed in southern and south-western China, at the same time with a few species extending into Vietnam, Myanmar, India, Bhutan, Japan and Thailand ( Cai et al. 2017, Möller et al. 2016, 2018, Xu et al. 2017). SW China is rich in species diversity of the genus in China, especially on the north-facing shady slope nearby the summit of southern Yunnan Province and most species occur in relatively restricted and geographically isolated localities with very few widely distributed ( Li and Wang 2005, Wei et al. 2010, Möller et al. 2011). Only three species of this genus were found in S. Gansu province before 2019, viz. Oreocharis farreri (W. G. Craib) M. Möller & A. Weber, O. glandulosa (Batalin) M. Möller & A. Weber and O. henryana Oliv. O. farreri was first published as Isometrum farreri base on the type specimens: Farrer et Purdom 262 [E, barcode no. 00135136, Fig. 3 ], which grows at low elevations on rather cool rocks or very steep banks of cool clammy soil that grows a fine film of moss in S. Gansu Province ( Craib 1920). O. glandulosa was first described as Didissandra glandulosa by A.T. Batalin in 1892, based on the specimens [LE, barcode no. 01043081, Fig. 4 ] from G.N. Potanin’s trip from 1884 to 1886, collected on the way from Songpan County, Tibetan Qiang Autonomous Prefecture of Ngawa, NE Sichang Province to Wenxian County, Longnan City, S. Gansu Province on 17 August 1885 ( Batalin 1892, Bretschneider 1898). O. henryana was described and illustrated, based on the type specimens: A. Henry 8999 [K, barcode no. 000858129, Fig. 5 ], growing on shady and damp rocks in montane regions of Sichuan Province ( Hooker 1890). No new species of Oreocharis were described from between the early 19th and late 20th Century in the regions, the new findings complementing the species richness of the genus in Central China. Due to the high endemism in the genus ( Chen et al. 2017b, 2018), Table 1 details the differences between these species growing in the same regions.

Obviously, the genus is special for its remarkable floral diversity and it has made this genus to be one of the most taxonomy-difficult groups in the family. The new species, Oreocharis flavovirens which has a light-yellow cylindrical corolla with a distinct upturned tube, is a good example. The shape of the corolla tube, cylindrical and upturned, is a distinct character that not many species in Oreocharis possess. If we only consider the similarity of corolla tube shape, it is close to Oreocharis tubiflora K.Y. Pan and O. argyreia Chun ex K.Y. Pan, including constriction at the mouth but the latter two are lacking the upturned corolla tube. Given the corolla shape, the corolla of several species of former Ancylostemon Craib are similar too, except the tubes are straight or slightly turned down, but not up, though the flowers are predominantly yellow (rarely pink in A. ronganensis K. Y. Pan= Oreocharis ronganensis (K.Y.Pan) Mich. Möller & A.Weber), but not greenish-yellow. On the other hand, the upturned tube is more reminiscent of former Opithandra wentsaii Z.Yu Li (= Oreocharis wentsaii (Z. Yu Li) M. Möller & A. Weber) and former Opithandra pumila (W.T.Wang) Wang (= Oreocharis pumila (W.T.Wang) Mich. Möller & A.Weber), only here the tubes of previous Opithandra are slightly more trumpet-shaped in dark pink or pink and have two fertile stamens rather than four ( Wang et al. 1998, Li and Wang 2005, Wei et al. 2010). All in all, the upturned corolla tube combined with its greenish-yellow colour could be used alone to differentiate the new species from others in the genus.

Furthermore, although the genus Oreocharis was redefined to accommodate species with distinctive floral morphologies from ten other genera, based on molecular phylogenetic studies in the last two decades, the evolutionary trends of the floral characters have not yet been understood comprehensively. The major causes of the incongruence and conflict between classical taxonomy and molecular phylogenetic studies for Oreocharis s.l. remain largely unexplored. There are other similar examples in Gesneriaceae of Asian, for example, Primulina s.l. ( Wang et al. 2011, Weber et al. 2011a) and Petrocodon s.l. ( Weber et al. 2011b, Lu et al. 2017).

Additional specimens examined (paratypes).

Gansu Province: Yuhe Provincial Nature Reserve, Longnan City, 24 September 2019, in fruit, Yun-Feng Gao et al.: WF19092401 (AHU).

Figures

Figure 1. Oreocharis flavovirens Xin Hong in natural habitat A habitat, growing on the surface of rocks B vegetative part of plants C top view of corolla D lateral view of corolla E bud, showing the shape and indumentum of calyx F young capsule. Scale bars: 2 cm (B); 1 cm (C-F).

Figure 2. Morphological character of Oreocharis flavovirens Xin Hong A-B different sizes of leaves (A adaxial leaves B abaxial leaves) C indumentum of petiole D abaxial leaf blades, showing veins and indumentum E cyme and infructescence F bracts G dissection of a flower H opened corolla, showing stamens and staminodes I pistils without corolla, showing stigma J young capsule K disc and calyx revolute of the young capsule. Scale bars: 2 cm (A-C); 1.5 cm (D, E); 3 mm (F, I, K), 1 cm (G, H, J).

Figure 3. Type of Oreocharis farreri (W. G. Craib) M. Moeller & A. Weber, stored in Herbarium of Royal Botanic Garden Edinburgh, No. E 00135136.

Figure 4. Type of O. glandulosa (Batalin) M. Moeller & A. Weber, stored in Herbarium of Komarov Botanical Institute, No. LE 01043081.

Figure 5. Type of Oreocharis henryana Oliv. stored in Herbarium of Royal Botanic Gardens, No. K 000858129.