Primulina cataractarum X.L. Yu & A. Liu, 2021

Ding, Cong, Liu, Ang, Yu, Xun-Lin & Zhang, Chun-Ping, 2021, Primulina cataractarum sp. nov. (Gesneriaceae) from limestone landform in Southern Hunan, China, Phytotaxa 511 (1), pp. 51-64 : 59-63

Primulina cataractarum X.L. Yu & A. Liu , sp. nov. ( Fig. 5–7 )

Diagnosis:— Primulina cataractarum is similar to P. porphyrea and P. rubribracteata in having purple corolla lobes and purple abaxial leaf surface, but differs from the latter two by having smaller (3–6 × 2–5 cm) ovate to rounded leaves, shorter (3–8 cm) petioles, shorter (5–8 cm) peduncle, 2 or no bracteoles and purple corolla tube outside, with several red-purple stripes inside and the top of adaxial side has a little yellow. Besides, the new species differs from P. porphyrea in larger bracts (15–25× 10–15 mm) and from P. rubribracteata in green bracts (not purple red).

Type: — CHINA. Hunan Province: Jianghua Yao Autonomous County, Qiaotoupu town [27°42’N, 108°48’E], elevation ca. 361 m. It grows in a water curtain cave, which hidden by the sheet of water cascading down, June 7, 2020 JH0001 (holotype, CSFI!, isotype, CSFI!& HIB!) .

Perennial herbs, rhizomes recumbent, ca. 2 cm long, ca. 5 mm in diameter. Leaves all basal, thickly chartaceous, ovate to round, 3–6 × 2–5 cm; apex rounded or obtuse, base asymmetrical, margin entire or slightly crenate, both surfaces with densely appressed bristles and sparely villous, leaf abaxial surface purple or reddish-purple; lateral veins 3–4 pairs; petiole 3–8 × 0.2 cm, densely spreading villous and long pubescent; cymes 2–5 (upright or bent), axillary, unbranched or with 1–2 branches, 2–6-flowered; peduncles 5–8 cm long, densely spreading villous and long pubescent; bracts 2, opposite, ovate or oval, 15–25 × 10–15 mm, apex slightly acuminate, margin repand, outside spreading villous, inner slightly pubescent, increased significantly in fruit period; bracteoles 2 opposite or without bractlet, oval, 10–15 × 5–8 mm, margin entire, outside spreading villous, inner slightly pubescent. Pedicels 0.4–1.2 cm long, densely pubescent. Calyx 5-parted nearly to the base, narrowly lanceolate, 6–9 × ca. 2 mm, outside densely villous inner sparsely puberulent. Corolla lobes purple, tube purple outside, with several red purple stripes inside and the top of adaxial side has a little yellow. Corolla ca. 3.5 cm, outside densely long pubescent, inside sparsely short pubescent; tube nearly tubular, inside having several reddish-purple stripes and a little yellow on top of adaxial, ca. 2.5 cm long, 1 cm in diam.at mouth; adaxial lip ca. 1 cm long, 2-lobed, lobes oval, abaxial lip ca. 1.4 cm long, 3- lobed, lobes elliptic, nearly isometric. Stamens 2, adnate to ca. 1cm above the base of the corolla tube, filaments ca. 1 cm long, geniculate from the middle, brown, sparsely pubescent; anthers elliptic, ca. 3 mm long, densely puberulent. Staminodes 3, lateral ones adnate to ca. 1 cm above the base of corolla tube, ca. 5 mm long, glabrous, the central one adnate to ca. 0.1 cm above the base of corolla tube, ca. 2 mm long, glabrous. Pistil ca. 2.5 cm long, ovary ca. 1.2 cm long, densely villous, style ca. 1.3 cm long, densely glandular puberulent; disc oblique, white, ca. 1 mm in height, margin serrate; stigma 2-cleft, covered with short pubescence. Capsule linear curved, 2.5–4.5 × 0.1–0.2 cm, densely puberulent.

Phenology:— Flowering in May , fruiting from May to June. Distribution and habitat:— Primulina cataractarum is only known from the type locality, Qiaotoupu town Jianghua Yao Autonomous County, Hunan Province, China. It grows on the surface and cracks of limestone cave under the waterfall .

Etymology:— The specific epithet refers to the habitat where the species was first found under the waterfall.

Conservation Status:— At present, Primulina cataractarum was only found in a population with ca. 150 individuals within 20 m 2 in its type locality, next to a forest farm under construction. The population is not in a protected area, a nature reserve or a park, and no protective measures are taken. Its habitat is vulnerable and subject to the destruction by human activities. Therefore, following the IUCN Red List Category ( IUCN 2019), the new species should be regarded as “Critically Endangered, CR B2 ab(ii) + C2 b”, because of its limited populations and vulnerable habitat .

Figures

FIGURE 5. Primulina cataractarum X.L.Yu & A.Liu. A. Plant B. Flower side view. C. Front view of flower. D. Opened corolla showing stamens and staminodes. E. Stamens. F. Stigma. G. Pistil. H. Bracts and bractlet. I. Calyx. J. Capsule. (Drawn by Jing Tian).

FIGURE 6. Primulina cataractarum X.L.Yu & A.Liu.A. Habitat. B. Flowering individual. C. Population. D. Left view of flower and both surfaces of leaves. E. Abaxial leaf blade surface and inflorescence and bracts. F. Corolla, stamens showing staminodes, pistil and disc. G. Front view of flower. H. Opened corolla showing stamens. I. Stigma. J. Inflorescence, bracts, bractlet and calyx. K. Bracteoles. L. Disc. M. Calyx. N. Mature capsule.

FIGURE 7. Holotype of Primulina cataractarum X.L.Yu & A.Liu. (CSFI JH0001).