﻿Petrocodonliboensis (Gesneriaceae), a new species from Guizhou, China

﻿Abstract Petrocodonliboensis Sheng H.Tang & Jia W.Yang is a new species of Gesneriaceae from Guizhou, southwestern China. The new taxon has a pale-yellow corolla and is most similar to P.luteoflorus. However, it differs from the latter by having a urceolate (vs. cannulate) corolla tube, an abaxial corolla lip 0.8–1.1 mm (vs. 2–2.2 mm) long, and filaments 1.5–1.7 mm (vs. ca. 7 mm) long that are straight (vs. S-shaped or geniculate near the middle). The new taxon is assessed as “Data Deficient” (DD) according to the IUCN standards.

During a field survey conducted in early July 2020 in Libo County, Guizhou Province, China, a population belonging to the genus Petrocodon (Gesneriaceae) was identified.Live plants with flower buds were cultivated in the Guizhou Botanical Garden.In late July 2020, they bloomed with pale-yellow flowers and for the first time, a corolla with straight filaments was observed.As the newly published species, viz., P. luteoflorus Lei Cai & F. Wen (Fan et al. 2020), which also has pale-yellow corollas, occurs in Libo County too, they were misidentified as P. luteoflorus.In late July 2021, they bloomed again, but only one picture of a flowering plant was captured by us because of the misidentification.In August 2022, the plants bloomed for the third time, and straight filaments were observed again.In September 2022, a field survey was conducted in Libo County to collect wild type plant specimens.The flowers of the cultivated and wild plants were identical.
In April 2017, live plants of P. luteoflorus (published in 2020) were introduced from Limingguan town, Libo County, which is its type locality, and bloomed in 2017 and 2018.In 2019, they perished due to inadequate care.Fortunately, we had already meticulously photographed the blossoms in 2017.In September 2022, we photographed the flowers at their original location with great care.The flowers of both cultivated and wild plants were indistinguishable.In November 2022, a second population without flowers was found in Yongkang Town, Libo County, and the shape and size of the leaf blades were the same as those of the plants from its type locality.Therefore, the leaf blade characteristics were stable.
Phenology.Flowering occurs from late July to early September, and fruiting in the wild is unknown; only capsules from the previous year were observed.
Etymology.The new taxon was named after its locality in Libo County, China.Vernacular name.The Chinese name is "Lì Bō Shí Shān Jù Tái" (荔波石山苣苔).Distribution and habitat.Only one population was found at the Daqikong Scenic Spot, Libo County, Guizhou Province, China.Plants were found growing on wet shady rocks in the valley, along with mosses, weeds, and shrubs.Preliminary conservation assessment.Only one population of approximately 200 mature individuals was found in the type locality.It is highly likely that more populations were present in this area.Until further investigation, the species should be designated as "Data Deficient" (DD) according to the IUCN standards (IUCN 2022).

Figure 1 .
Figure 1.Petrocodon liboensis A habitat B, C flowering plant D adaxial and abaxial surfaces of leaf blade E cymes, and bracts (inset) F flower in front view G flower in side view H, I opened corolla J stamens, and anthers (inset) K pistil, and cross section of ovary (inset) L capsules, and seeds (inset) (Photographs by Sheng-Hu Tang).

Figure 2 .
Figure 2. Petrocodon luteoflorus A habitat B flowering plant C adaxial and abaxial surfaces of leaf blade D cymes, and bracts (inset) E flower in front view F flower in side view G calyx segments H opened corolla I stamens J pistil, and cross section of ovary (inset) K capsules L seeds (Photographs by Sheng-Hu Tang).