Paraboea sinensis var. glabrissima W.H.Chen & Y.M.Shui, 2020

Chen, Wen-Hong, Guo, Shi-Wei, Nguyen, Hieu Quang, Chen, Li & Shui, Yu-Min, 2020, Two new taxa of Gesneriaceae in the karst regions in North Vietnam, PhytoKeys 157, pp. 217-226 : 217

Paraboea sinensis var. glabrissima W.H.Chen & Y.M.Shui var. nov. Figure 2

Type.

Vientam, Pho Tho Province: Xuan Son County, Xuan Son National Park, 21°07'49.3"N, 104°57'09"E, 463 m a.s.l., 8 April 2016, Y. M. Shui, W.H. Chen, C. Liu, H.Q. Nguyen, H.T. Nguyen, N.Q. Chuong CK909 (holotype, KUN!; isotype, CPC!=Herbarium of Center for Plant Conservation of Vietnam).

Diagnosis.

The new variety is similar to Paraboea sinensis (Oliv.) Burtt var. sinensis in its morphology of habit, calyx, corolla and fruits, but differs in its young leaf abaxially, stem and peduncle sparsely and thin pannose (vs. dense and thick pannose), acute top of leaves (vs. acuminate), pistil glandular-pubescent or pubescent (vs. glabrous).

Subshrubs. Stem erect, 50-80 cm tall, ca. 0.3 cm in diam., with many branches, pannose when young. Leaves opposite, equal to subequal in pairs on the stem; petiole 1-10 cm long, pannose when young; blade herbaceous, slightly asymmetric, oblong to obovate, 9-19 × 3.5-8 cm, base cuneate, apex acute, margin denticulate from the base, adaxially glabrous, abaxially sparsely pannose when young; venation penninerved, lateral veins 7-12 on each side of the midrib. Cymes axillary near branch apices; peduncle 1.5-4.5 cm long, sparsely pannose; bracts caducous; pedicel 1.4-2 cm long, sparsely pannose; bracteoles caducous. Calyx zygomorphic, 2-lipped, adaxial calyx ca. 1 cm long, 3-lobed to the middle, lobes rounded ca. 0.5 × 0.5 cm, abaxial calyx 2-lobed to the base, lobes obovate, ca. 1.2 × 0.6 cm, apex round, margin entire, outside glabrous, inside glabrous. Corolla campanulate, zygomorphic, 2-2.3 cm long, ca. 1.3 cm wide at the throat, both sides glabrous, tube 1-1.4 cm long; limb 2-lipped; adaxial lip 2-lobed, lobes broadly ovate, ca. 0.9 × 1.5 cm; abaxial lip 3-lobed, lobes broadly ovate, middle lobe ca. 0.7 × 1.2 cm. Stamens 2, adnate to the corolla base; anthers glabrous; filaments ca. 1 cm long, pubescent, staminodes 3, glandular-pubescent, lateral ones 2.5-3.0 mm long, adnate to the corolla tube base, the middle one ca. 1 mm long, adnate to the corolla tube ca. 2 mm above the base. Disc absent. Pistil ca. 1.2 cm long; ovary linear, ca. 0.8 cm long, sparsely glandular-pubescent or pubescent; style linear, ca. 0.4 cm long, glandular-pubescent; stigma 1, capitate. Capsule linear, spirally twisted, 2.5-3.7 cm long, glabrous.

Phenology.

Flowering from March to April, fruiting from April to May.

Etymology.

The word " glabrissima " indicates the glabrous surface across the whole plant except the young leaves (Fig. 2A ), which become glabrous as soon as the leaves become mature. In this manner, it is different from the original variety of Paraboea sinensis var. sinensis .

Distribution and habitat.

The new variety only occurs in Xuan Son County, Pho Tho Province and grows in soil, on rocks in limestone forests.

Provisional conservation status.

Based on field surveys and detailed discussions with Vietnamese colleagues, including Hieu Quang Nguyen, this new variety has only been observed in the Xuan Son National Park. There were only a total of 30 mature individuals, so we provisionally considered it as Critically Endangered (CR): B1b (v) + 2b (v). ( IUCN 2012; IUCN Standards and Petitions Subcommittee 2017).

Note.

This new variety is very similar to the original variety of Paraboea sinensis in subshrub habit, obovate calyces and twisted fruits, but different in the almost glabrous habit (Table 1 ; Wang et al. 1998; Xu et al. 2008). Furthermore, the new variety is covered by pannose indumenti on the young leaves (Fig. 1A ), but quickly becomes glabrous on the mature ones, while pannose indumenti consistently covers the original variety on both young and mature leaves (Figs 1G, H ). Additionally, the top of the leaf is acute rather than acuminate in the original variety. It is necessary to explore the morphology diversity and genetic differentiation of Paraboea sinensis in the future, a wide-distributed species in the genus.

Figures

Figure 1. The distribution of Paraboea sinensis var. glabrissima W. H. Chen & Y. M. Shui var. nov. (triangle) and Primulina xuansonensis W. H. Chen & Y. M. Shui sp. nov. (square).

Figure 2. Paraboea sinensis var. glabrissima W. H. Chen & Y. M. Shui, var. nov. (A-F) and P. sinensis (Oliv.) Burtt var. sinensis (G & H) A habit, arrows indicate the young leaves with thin brown pannose B inflorescence with twisted fruits, arrows showing the indumentum of abaxial surface of leaf (pe = peduncle, abl = abaxial leaf) C face view of flower D dorsal view of the calyx, the arrow showing the coherent position E birds-eye view of opened corolla F stamens and staminodes, arrows showing the staminodes G habitat H inflorescence.