Pilea danxiaensis L.F.Fu, A.K.Monro & Y.G.Wei, 2022

Fu, Long-Fei, Xiong, Chi, Monro, Alexandre K., Fan, Qiang, Chen, Zai-Xiong, Wen, Fang, Xin, Zi-Bing, Wei, Yi-Gang & Liao, Wen-Bo, 2022, Pilea danxiaensis (Urticaceae), a new species in the Danxia landform from Guangdong, China including a description of the entire chloroplast genome, PhytoKeys 204, pp. 109-119 : 109

Pilea danxiaensis L.F.Fu, A.K.Monro & Y.G.Wei sp. nov.

Fig. 3

Type.

China. Guangdong: Danxiashan National Park, Renhua County, Shaoguan City , 25.020°N, 113.752°E (WGS84), elev. 134 m, 2 April 2022, Liao Wen-Bo, Fan Qiang and Liao Li-Juan DNPC1728 (holotype IBK; isotypes IBK, SYS) .

Diagnosis.

Most similar to Pilea sinocrassifolia C.J.Chen from which it can be distinguished by the longer stipule (1.3-1.5 mm versus 1 mm), petiole (2-8 mm versus 0.2-0.6 mm) and staminate peduncle (8-25 mm versus 1.5-7 mm).

Description.

Herbs prostrate, stem 30-200 × 1 mm, light green when fresh, drying yellowish-brown, glabrous, succulent, cystoliths fusiform, 0.2-0.4 mm long. Stipules, 1.3-1.5 × 1.7-2.1 mm, reniform, drying brown, papery, with dense cystoliths. Leaves petiolate, distichous, clustered towards the stem apex; petioles 2-8 mm long, glabrous, cystoliths densely scattered; laminae at each node equal or subequal, 3-15 × 5-20 mm, length: width ratio 0.7-0.9:1, suborbicular to broadly ovate, succulent, papery when dry; adaxial surface drying grey-green, dark green when fresh, glabrous, with cystoliths densely scattered, ca 0.3 mm, linear or fusiform; abaxial surface drying light green, green when fresh, glabrous, rugose when dry, 3-veined, secondary veins 3-6 pairs, borne at 45-60° to the midrib, with cystoliths sparsely scattered, ca 0.3 mm, linear or fusiform; apex obtuse or subretuse, base cuneate, rounded or subtruncate, margin entire and revolute. Inflorescences in upper nodes, appearing terminal, monoecious. Staminate inflorescences 10-30 mm, bearing 10-25 flowers in a capitulum or occasionally a glomerule; peduncle 8-25 × 0.5 mm, glabrous; pedicels ca 0.8 mm, glabrous. Staminate flowers 1 × 1 mm, green, drying light green, sepals 4, ca 1.8 mm; valvate, elliptic, glabrous, the subapical appendage ca 0.1 mm, corniculate, glabrous; stamens 4. Pistillate inflorescences 10-20 mm, bearing 20-50 flowers in a cyme or glomerule; peduncle 8-18 × ca 0.5 mm, glabrous; pedicels ca 0.5 mm. Pistillate flowers ca 0.5 mm, sepals 3, subequal, ca 0.3 mm, valvate, triangular-ovate, glabrous, the subapical appendage ca 0.1 mm. Infructescences 15-20 mm; peduncle 15-18 mm; achenes 0.68-0.72 × 0.40-0.46 mm, ovoid, spinulose-verrucose, rarely smooth.

Distribution and habitat.

Pilea danxiaensis L.F.Fu, A.K.Monro & Y.G.Wei is known from a single locality in Renhua County, Shaoguan City, Guangdong, China, where it grows in a ravine on the Danxia landform, a petrographic geomorphology formed from Cretaceous sandstones and conglomerates.

Phenology.

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

Etymology.

The species epithet is named after the Danxia landform with which the species is associated.

Vernacular name.

dān xiá lěng shuǐ huā (Chinese pronunciation); 丹霞冷水花 (Chinese name).

Conservation status.

At present, Pilea danxiaensis is known from a single locality, the Danxiashan National Park. The park covers 140 km2 and the massif from which the type collection was made encompasses ca 114 km2 (Google Earth Pro). Within that locality, the population of P. danxiaensis is estimated to number between 1,000 and 5,000 individuals distributed between 10 sub-populations, of which only one has been directly observed. A remote survey of the Danxiashan National Park using Google Earth Pro, suggests that the protected area itself is well protected and we observed no active threat or continuing decline in population size. Pilea danxiaensis is therefore classified as Least Concern (LC).

Additional specimen examined.

China. Guangdong: Danxiashan National Geopark, Renhua County, Shaoguan City, 25.004°N, 113.655°E (WGS84), elev. 466 m, 20 April 2018, Fan Qiang and Huang Yan-Shuang 16993 (IBK, SYS).

Figures

Figure 3. Plate of Pilea danxiaensis A habitat B habit C leaves and inflorescence D stipules E staminate inflorescence F pistillate inflorescence G staminate flower H pistillate flower I achene with pistillate sepals J LM of achene K SEM of achene.