Phoebe hekouensis Bing Liu, W.Y. Jin, L.N. Zhao & Y. Yang, 2020

Liu, Bing, Jin, Wei-Yin, Zhao, Li-Na & Yang, Yong, 2020, A new species of Phoebe (Lauraceae) from south-western China, PhytoKeys 140, pp. 101-106 : 101

Phoebe hekouensis Bing Liu, W.Y. Jin, L.N. Zhao & Y. Yang sp. nov. Figs 1 , 2

Type.

China. Yunnan: Hekou Yao Minority Autonomous County, Nanxi Town, Hua-Yu-Dong, alt. ca. 140 m elev., 5 Apr 2014, Bing Liu, Y. Yang, Q.W. Lin, L. Jiang & X.J. Li 1988 (Holotype: PE; Isotypes: PE).

Diagnosis.

This new species resembles P. megacalyx in having tomentose twigs and large tepals, but differs from the latter species by broader leaves (12-18 cm vs. 4.5-11.5 cm), shorter inflorescences (10-15 cm vs. up to 23 cm), densely pubescent ovary (vs. only pubescent at the apical portion) and the enlarged stigma (vs. inconspicuous); also similar to P. macrocarpa in that the twigs of both being robust and tomentose, but distinguished by the longer tepals ca. 9-13 mm (vs. ca. 4 mm).

Description.

Trees, ca. 12 m tall, bark greyish-brown. Branchlets robust, ca. 9 mm in diam., ridged, densely brown tomentose, possessing prominent dispersed leaf scars and clustered bud scale scars. Leaves alternate, usually clustered to somewhat verticillate at the apex of branches, coriaceous, oblanceolate, 25-45 × 12-18 cm, apex acuminate, base acute, upper surface glabrous, midrib impressed on the upper surface, principal lateral vein 18-30 pairs, immersed in the upper surface, both the midvein and the lateral veins prominently elevated on the lower surface, yellowish pubescent; petioles 1-2 cm long, brown tomentose. Inflorescences paniculate, 2-6 clustered at the apex of branches in between the clustered leaves; panicles robust, many-flowered at the apex, 10-15 cm long, densely yellow-brown tomentose, not branched in the lower half, usually few-branched in the distal portion and the flowers appearing to be clustered at the apex; peduncles 7.5-8.5 cm long, more than 2/3 of the total length, tomentose; bracts 2 cm long, tomentose. Flowers yellowish-white; subsessile. Bracts linear, brownish tomentose. Tepals in two whorls, subequal in length, elliptic, tepals of the outer whorl 9-13 mm long, ca. 6 mm broad, those of the inner whorl linear and narrower, ca. 4 mm broad, brownish tomentose on both sides. Fertile stamens 9, 4-loculed, the four locules arranged in trapezoid pattern; filaments 4-6 mm long, brownish pubescent, each filament of the third whorl bearing two yellow glands at the base; glands ovoid, stalked, stalks pubescent. Staminodes sagittate, ca. 4-6 mm long, possessing pubescent stalks. Ovary obovoid, brown tomentose; style straight and thread-like, ca. 3 mm long, pubescent, glabrescent toward distal end; stigma enlarged, disc-shaped. Flowers collected in April. Fruit not seen.

Distribution.

China. Yunnan, Hekou Yao Minority Autonomous County (Fig. 3 ).

Habitat.

In limestone ravines, near water.

Etymology.

The epithet " hekouensis " is after the type locality Hekou Yao Minority Autonomous County of Yunnan Province, south-western China.

Preliminary conservation status.

We have conducted field investigations in south-eastern Yunnan Province of China for ten years, but have found only one tree at the type locality, and no fruiting specimens were observed. It is uncertain if the species is endemic to China or is also distributed in adjoining Vietnam due to lack of field investigations in Vietnam. Based on IUCN Red List Categories and Criteria ( IUCN 2012), we considered the new species as Critically Endangered (CR) in China. To conserve the species, we propose to take actions on reproduction of the tree in botanical gardens in the future.

Figures

Figure 1. Morphology of Phoebe hekouensis. A Flowering branch, showing oblanceolate leaves and terminal inflorescences B, C inflorescences, these being panicles with long peduncles and branched only in the distal portion D flower with tepals removed, showing stamens, glands and staminodes.

Figure 2. Illustration of Phoebe hekouensis to show morphological details. A Flowering branch B leaf, showing the oblanceolate shape and the ascending principal lateral veins C leaf portion magnified to show veinlet reticulations D tepals, depicting shape and pubescence of adaxial and abaxial side E fertile stamen of the first and second whorls F fertile stamens of the third whorl G staminodes, note sagittate head and pubescent stalk H pistil, showing pubescence.

Figure 3. Distribution map showing the only known locality of Phoebe hekouensis (▲).