Pilea cavernicola A.K. Monro, C.J. Chen & Y.G. Wei, 2012
|
publication ID |
https://dx.doi.org/10.3897/phytokeys.19.3968 |
|
persistent identifier |
https://treatment.plazi.org/id/0BB3C0C4-0FF4-53D2-955D-F94545F8C214 |
|
treatment provided by |
|
|
scientific name |
Pilea cavernicola A.K. Monro, C.J. Chen & Y.G. Wei |
| status |
sp. nov. |
Pilea cavernicola A.K. Monro, C.J. Chen & Y.G. Wei sp. nov. Figs 1 A-E View Figure 1 , 2 A-C View Figure 2 , 3 A-B View Figure 3
Diagnosis.
Most similar to Pilea scripta from which it can be distinguished by the shorter stems, ovate rather than elliptic or oblong leaves, stipules with auriculate bases rather than deltate ones, the staminate tepals not ribbed and the sub-compressed elliptic rather than ovoid achenes with smooth non verrucose surfaces.
Type.
China. Guangxi: Fengshan County, Paoli Town, Yangzi cave, 490 m, 024°23'22.2"N, 107°03'59.1"E (DMS), 9 May 2010, A. K. Monro & Y.G. Wei 6669 (holotype: IBK; isotypes: BM001001214, MO, PE).
Description.
Herb to 50 cm, terrestrial. Stems erect, drying brown, maroon to green when fresh, glabrous or pubescent at the nodes and towards the base, where pubescent the hairs 1.0 mm, erect, crooked, cystoliths fusiform, the internodes 23-300 × 1.5-2.5 mm, angulate to square in cross-section, striate. Stipules 2.5-4.0 mm, auriculate-ovate, drying brown. Leaves petiolate, distichous; petioles at each node subequal or unequal by ratio 1:1.1-2.8, 12-33 mm, pubescent or glabrous, where pubescent the hairs 1.0-1.25 mm, erect, weakly curved or crooked; laminae at each node equal or subequal, 26-90 × 12-46 mm, ovate, subchartaceous; 3-nerved, the lateral nerves visible for 2/3 or more of the lamina length, secondary nerves 7-11 pairs, borne 60-75° to the midrib, weakly curved; upper surface drying dark brown, green or bronze when fresh, glabrous, cystoliths densely scattered, less than 0.125 mm, elliptic and punctiform, midrib and secondary nerves sunken; lower surface drying brown to dark brown, pale green or flushed bronze-purplish when fresh, pubescent, the hairs 0.75-1.0 mm, appressed, weakly curved, eglandular; base symmetrical, cuneate or weakly decurrent; margin serrate, the basal 1/8-1/4 entire; apex symmetrical, cuspidate. Inflorescences 4-8 per stem, unisexual, staminate and pistillate inflorescences synchronous, born on separate stems; bracts 0.75 mm; bracteoles 0.5 mm. Staminate inflorescences 2 per axil, 17-22 mm, bearing 45-90 flowers in a loose cyme; peduncle 1/4 or less inflorescence length, 0.75 mm in diameter, glabrous, occasionally with cystoliths present; pedicels 0.50-1.5 mm, glabrous. Staminate flowers 1.5 × 1.5 mm immediately prior to anthesis, green-brown; tepals 4, 1.75 mm, valvate, fused for their basal 1/3, elliptic, glabrous, the subapical appendage less than 0.25 mm, corniculate, glabrous; stamens 4. Pistillate inflorescences 1 or 2 per axil, 8-13 mm, bearing 150-300 flowers in a loose cyme; peduncle 1/4 to 1/3 inflorescence length, 0.75 mm in diameter, densely covered in cystoliths, cystoliths punctiform, glabrous; pedicels 0.25-0.75 mm, glabrous. Pistillate flowers 0.50-0.75 mm, tepals 3, unequal, glabrous, adaxial tepal 0.50-0.75 mm, oblong or ovate, the dorsal tepal appendage 0.50-0.75 mm, oblong, markedly thickened almost hood-like; the lateral tepals 0.375-0.50 mm, asymmetrically ovate. Infructescences 8-13 mm; peduncle 1/4 to 1/3 infructescence length; achenes 0.75 × 0.675 mm, sub compressed, asymmetrically ellipsoid, the abaxial margin very narrowly thickened.
Distribution.
North West Guangxi Province, ca 500-1000 m, caves in limestone karst, growing at any point from the back to the entrance of the cave, PAR 0.02-1.39 mmol/m2/sec (ca 0.04-2.78 % full daylight).
Etymology.
The species name refers to the cave-dwelling habit of this species.
Paratypes.
CHINA: Guangxi Province: Fengshan County, Paoli Town, Sidui Village, Xibi cave, 740 m, 024°24'38.5"N, 107°04'53.5"E (DMS), 8 May 2010, A. K. Monro & Y.G. Wei 6654 (IBK, BM001001215, PE, MO).
Discussion.
Comparison of the holotype and paratype material with type specimens from the herbaria listed in the methods section recovered Pilea scripta (Buch.-Ham. ex D.Don) Wedd. and Pilea gracilis Handel-Mazzetti as most similar to Pilea cavernicola . Pilea scripta can be distinguished from Pilea cavernicola based on stem height, leaf shape, stipule shape, staminate tepal morphology and achene morphology as summarised in Table 1 View Table 1 . Pilea gracilis can be distinguished from Pilea cavernicola based on leaf shape, stipule morphology, staminate and pistillate inflorescence morphology and achene morphology as summarised in Table 2 View Table 2 .
Pilea cavernicola falls within Weddell’s (1869) Dentatae-Gerontogeae subdivision and Chen’s (1982) Urticella Section of the genus.
Conservation status. Using IUCN criteria ( IUCN 2001) Pilea cavernicola is considered Vulnerable (VU). Pilea cavernicola is known from only two localities (IUCN criteria D2, number of locations <5). At these localities the populations of this species comprises ca 100-200 mature individuals (IUCN criteria D1, number of mature individuals <1000). Using the IUCN methodology our Global Conservation Assessment for Pilea cavernicola is Vulnerable (VU)based on criteria D1 and D2: population size and number of locations combined with a plausible future threat that could drive this taxon to Endangered in a very short time. Plausible threats include the location of both caves at the edge of agricultural land, the use of the entrance of one of the cave localities (Yangzi cave) to cultivate medicinal plants ( Corydalis sp.), requiring the terracing and tilling of the substrate. In addition mining is growing rapidly in the whole region and any localities close to roads are vulnerable to exploitation.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.