Petrocosmea dejiangensis Sheng H. Tang & Jian Xu 2022, sp. nov.
Creators: name: Xu, Jian
name: Li, Sa
name: Tang, Sheng-Hu
name: Ren, Qi-Fei
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Lamiales
Gesneriaceae
Petrocosmea
Petrocosmea dejiangensis

description: Petrocosmea dejiangensis Sheng H.Tang & Jian Xu, sp. nov., Figure 1
Type:— CHINA. Guizhou Province, Dejiang County, Nangan Town, at approximately 610 m elev., 28°22′12″N, 107°53′24″E [the voucher from plants cultivated at the Guizhou Botanical Garden, and collected in the locality presented on 12 May 2020], 3 May 2021, Sheng-Hu Tang 2021002 (holotype GZAC!).
Petrocosmea dejiangensis has a highly fused upper lip. This important character is shared by 21 species of Petrocosmea. The new species is most similar to P. martini (Fig. 2) in the indumentum of the petiole, leaf blade, filaments, and ovary, but differs from it in having inconspicuous bracts (vs. conspicuous), two dark blue-purple stripes inside along the entire corolla tube (vs. two purple spots inside the tube under the filaments), throat blue-purple (vs. white), anthers shorter than filaments (vs. anthers subequal to filaments in length), and stigma apex rounded (vs. flat).
Perennial herbs, stemless. Rhizome short, 3–4 mm long. Leaves all basal, 10 to 20; the inner leaves with petioles 0.5–1.5 cm long or absent, the outer leaves with petioles 3.5–6 cm long, petioles sparsely or densely descending pilose; leaf blades subcordate or suborbicular, 9.2–12.5 × 9–12.2 mm, apex obtuse or rounded, base cordate, and margin crenate, papery when dry, both adaxial and abaxial blade surfaces densely pilose, ca. 0.5 mm long, lateral veins adaxially and abaxially inconspicuous, 2–3 on either side of the midrib. Cymes 1–9, one flower per cyme; peduncles 4.5–5.8 cm long, sparsely ascending pilose, and densely appressed pilose; bracts absent, rarely two, nearly opposite, inconspicuous, 0.3–0.5 mm long, sparsely pilose; pedicels 1.5–2.5 cm long, sparsely ascending pilose and densely appressed pilose. Calyx zygomorphic, densely erect pilose outside, glabrous inside; adaxial calyx lip 5.2–5.4 mm in length, 3-lobed nearly to the base, lobes 3.9–4.1 × 1.1–1.2 mm, lanceolate, apex acuminate; abaxial calyx lip 2-lobed to the base, lobes 5–5.7 × 1.3–1.5 mm, lanceolate, apex acuminate. Corolla blue-purple, 12.9–14.3 mm long, puberulent outside, glabrous inside; tube 4.1–4.4 mm long, broadly tubular, two dark blue-purple stripes extending inside along the entire corolla tube length; throat blue-purple, with two dark blue stripes; adaxial corolla lip 2.2–2.6 mm long, much shorter than abaxial corolla lip, indistinctly 2-lobed, apex emarginate, margin recurved; abaxial corolla lip 9–10 × 11.7–12.8 mm, 3-lobed to the middle, lateral lobes obovate or ovate, 4.2–5.5 × 4.1–4.3 mm, the middle one obovate or ovate, 4.5–5 × 4.1–4.5 mm. Stamens two, included, adnate to the corolla tube near the base; filaments 3.5–4 mm long, densely glandular puberulent, curved near the middle; anthers ovate, ca. 2 × 1.7 mm, dorsifixed, coherent at apex; parallel thecae, not confluent at apex, poricidal near the apex, sometimes dehiscing longitudinally from apex to above the middle. Staminodes three, included, adnate to the adaxial side of the corolla tube near the base, ca. 0.8 mm long, glabrous. Pistil 7.5–8.3 mm long; ovary densely appressed pilose, narrowly ovoid, 2–2.5 mm long, ca. 1.0 mm in diameter; style 5.5–5.8 mm long, 0.3 mm in diameter, glabrous; stigma nearly globose, ca. 0.35 mm in diameter, apex rounded. Capsules unknown.
Phenology:— Flowering occurs from April to May. Fruiting in the wild is unknown but likely occurs from September to October; only young fruits were observed.
Etymology:— The new taxon is named after the type locality, Dejiang County, China.
Vernacular name:— The Chinese name is “Dé Jiāng Shí Hú Dié” (德江石Mự).
Distribution and habitat:— Three populations with nearly 120 mature individuals were found at Nangan town, Dejiang County, Guizhou Province, China. The plants grew on moist shady rocks in valleys at an elevation of ca. 600– 700 m. The main companion species were Platycarya strobilacea Siebold & Zuccarini (1843: 741–742), Lindera communis Hemsley (1891: 387), and Carpinus sp. Linnaeus (1753: 998) sp.
Conservation status:— Each time we visited the area, we discovered a new population. Three populations with approximately 120 mature individuals were found at and near the type locality. It is highly possible that more populations are present in the area. Until further investigation, the species should be designated as “Data Deficient” (DD) according to the IUCN standards (IUCN 2019).
Morphological affinities:— Although Petrocosmea dejiangensis and P. martini are similar in the shape of corolla, they differ in the morphology of bracts, color marks in the corolla, stamens, and the stigma. We have found three populations of P. dejiangensis at and near the type locality. The relatively smaller plant and leaf blades, the presence of two dark blue-purple stripes inside along the entire length of the corolla tube, anthers shorter than filaments, and stigma apex rounded were stable characters both in the wild and in the greenhouse. The detailed morphological comparison is shown in Table 1, as well as an identification key to the morphological alliance of P. dejiangensis.
Additional specimens examined (paratype):— CHINA. Guizhou Province: Dejiang County, Nangan Town, approximately 610 m, 29 August 2021 (young fruit), Jian Xu, Xuanze He & Shuo Yang DJ 20210829001 (GZAC!, CSH, IBK).
description: Published as part of Xu, Jian, Li, Sa, Tang, Sheng-Hu & Ren, Qi-Fei, 2022, Petrocosmea dejiangensis (Gesneriaceae), a new species from Guizhou, China, pp. 17-23 in Phytotaxa 539 (1) on pages 18-21, DOI: 10.11646/phytotaxa.539.1.2, http://zenodo.org/record/6345899