Tuesday, April 6, 2021

[Botany • 2021] Petrocodon albinervius (Gesneriaceae) • A New Species from Limestone Areas in southwestern Guangxi, China

Petrocodon albinervius D.X. Nong & Y.S. Huang, 

in Nong, Huang, Nong & Huang, 2021.
 白脈石山苣苔 ||  taiwania.ntu.edu.tw

Petrocodon albinervius D.X. Nong & Y.S. Huang (Gesneriaceae) is described and illustrated as a species new to science occurring in the limestone area of southwestern Guangxi, China. It shows overall most similarity with P. ionophyllus F. Wen, S. Li & B. Pan, P. integrifolius (D. Fang & L. Zeng) A. Weber & Mich. Möller and P. ainsliifolius W.H. Chen & Y.M. Shui in leaf shape, but differs in several characters such as the leaf blade indumentum, leaf veins coloration, the size and shape of bracts, the number of cymes per plant and flowers per cyme, and the shape of the stigma. Besides a diagnosis and detailed description, we also provide ecological information, photographic images, a table and taxonomic notes to distinguish several other morphologically similar Petrocodon species and proposed conservation status for this species.

Keyword: limestone flora, new taxon, Petrocodon ainsliifolius, Petrocodon integrifolius, Petrocodon ionophyllus, taxonomy

Fig. 2.  Petrocodon albinervius sp. nov.
A. Habitat. B–C. Habit in natural habitat. D. Leaf blade. E. Inflorescences. F. Flower buds. G. Flowers in oblique top view. H–I. Flowers in front view. J. Flowers in top view. K–L. Opened corolla. K,
Photographed by H.-Z. Lv (GXMG).

Fig. 1. Petrocodon albinervius sp. nov.
A. Habit. B. Opened corolla (showing stamens and staminodes). C. Calyx and pistil. D. Stigma.
Illustration by W.-H. Lin (IBK) based on specimen D.-X. Nong & Y.-S. Huang Y1219.


Petrocodon albinervius D.X. Nong & Y.S. Huang, sp. nov

Diagnosis: Petrocodon albinervius is morphologically similar to P. ionophyllus, P. integrifolius and P. ainsliifolius, but can be easily distinguished from P. integrifolius and P. ainsliifolius by its densely pubescent lamina (vs. densely white strigose lamina), ca. 8 mm long filaments (vs. ca. 3 mm long filaments), undivided stigma (vs. divided stigma). It also can be distinguished from P. ainsliifolius by its elliptic bracts (vs. linear bracts). Petrocodon albinervius most resembles P. ionophyllus in the leaf shape and style, but differs from the latter by its densely pubescent and pale green lamina (vs. sparsely strigose and purplish green to purplish brown lamina), cymes 3–7 per plant and flowers 4–30 per cyme (vs. cymes 1–2 per plant and flowers 3– 5 per cyme), elliptic bracts ( vs. lanceolate bracts), undivided and hippocrepiform stigma (vs. bilobed stigma, with ovate lobes).  

Etymology: The species epithet “albinervius” refers to the distinctive leaf blade with silvery veins. The Chinese name is proposed here as “白脈石山苣苔”. Phonetics: “Bái Mài Shí Shān JùTái”.

 Distribution and Ecology: The new species is endemic to Guangxi and known only from the type locality (Fig. 4). It grows on moist and shaded rocky faces of steep rocky slope under evergreen broad-leaved forests at an elevation of 800–850 m. The slope is facing northwest and at an angle of up to 60 degrees. The tree cover is up to 12 m tall, the canopy cover is 75%, the shrub layer cover is 85%, and the herb layer cover is 35%. Associated species include Begonia picturata Yan Liu, S.M. Ku & C.I. Peng (Begoniaceae), Pseudochirita guangxiensis (S.Z. Huang) W.T. Wang var. glauca Y. G. Wei & Yan Liu and Lysionotus oblongifolius W.T. Wang (both Gesneriaceae), Cymbidium lancifolium Hook. (Orchidaceae), Vaccinium dunnianum Sleumer (Vacciniaceae), and Ardisia carnosicaulis C. Chen & D. Fang (Myrsinaceae) amongst others.

Dong-Xin Nong, Bao-You Huang, Shi-Yue Nong and Yu-Song Huang. 2021. Petrocodon albinervius, A New Species of Gesneriaceae from Limestone Areas in southwestern Guangxi, China. Taiwania. 66(2); 135-140. DOI: 10.6165/tai.2021.66.135