Petrocosmea panzhouensis Sheng H.Tang & Tao Peng, 2022

Tang, Sheng-Hu, Zhang, Jian-Hua, Peng, Tao & Guo, Ying, 2022, Petrocosmea panzhouensis (Gesneriaceae), a new species from Guizhou, China, Phytotaxa 572 (3), pp. 225-231 : 227-230

Petrocosmea panzhouensis Sheng H.Tang & Tao Peng , sp. nov., Figure 1

Type:— CHINA. Guizhou Province, Panzhou County, Pugu Town , Niangniang Mountain , 26°04′45.56″N, 104°49′14.83″E, approximately 1472 m elev., 9 May 2022, Sheng-Hu Tang 202205001 (Holotype: CSH [ CSH0193338 ]!, Isotype: CSH!, GZBG!)

Petrocosmea henryi and P. weiyigangii are the only other two species of the genus with lobed leaves. Petrocosmea panzhouensis can be easily distinguished from the first by bracts spathulate, rarely oblanceolate (vs. linear or lanceolate), adaxial corolla lip apex 2-lobed to near middle (vs. emarginate or obtuse), anthers triangular, 1.7–1.8 mm long (vs. sagittate, 4.5–5 mm long). The new taxon can be easily distinguished from P. weiyigangii by adaxial corolla lip apex 2-lobed to near middle (vs. emarginate), straight filaments and densely glandular puberulent (vs. geniculate near middle and white pilose).

Herbs, perennial, stemless. Rhizome short, cylindrical, 7–10 mm long, 4.7–8.4 mm in diameter. Leaves all basal, 20 to 70; the inner leaves with petioles 5–20 mm long, the outer leaves with petioles 20–84 mm long, 1.1–1.3 mm in diameter, petiole densely pubescent and sparsely villous; leaf blade papery when dry, broadly ovate or suborbicular, 13–21.9 × 15.5–25.2 mm, adaxially densely pilose, abaxially densely pubescent, base broadly cuneate, suborbicular or truncate, sometimes peltate, margin irregularly lobed, apex obtuse or suborbicular; lateral veins 3–4 on either side of the midrib, adaxially inconspicuous or slightly impressed, abaxially prominent. Cymes 1–26, one flower per cyme; peduncle 22.2–48.5 mm long, 1–1.3 mm in diameter, densely pubescent and sparsely pilose; bracts 2, opposite, spathulate, rarely oblanceolate, 1.9–3.3 × 0.6–1.6 mm, margin entire, both outside and inside pilose; pedicel 11.2–32.5 mm long, 0.5–0.8 mm in diameter, densely pubescent and sparsely pilose. Calyx zygomorphic, outside densely pilose, inside glabrous; adaxial calyx lip 3.6–4.3 mm long, 3-parted from near base, segments equal, lanceolate or ovate-lanceolate, 2.6–3.3 × 0.8–1.3 mm, margin entire, apex acuminate; abaxial calyx lip 2-parted from base, segments equal, ovate-lanceolate or lanceolate, 3.8–4.9 × 1.3–1.5 mm, margin entire, apex acuminate. Corolla blue-purple, 14.6–16.2 mm long, outside densely puberulent, inside glabrous; tube 3.6– 6.5 mm long, 6–7 mm in diameter at mouth, 3–4 mm in diameter at base, subcampanulate, two dark blue-purple spots inside the tube beneath the anthers; throat blue-purple, without spots or stripes; limb distinctly 2-lipped, adaxial corolla lip erect, 4.9–5.5 × 6–8.9 mm, 2-lobed to near the middle, lobes ovate or broadly ovate, overlapped, 3.7–4.1 × 3.6–5.1 mm; abaxial corolla lip 8.7–10.8 × 14.5–16.9 mm, 3-lobed to near the middle, lobes subequal, ovate or broadly ovate, 5.4–6.7 × 5.1–7.4 mm. Stamens 2, connivent, adnate to the corolla tube near base, included; filaments 1.3–1.8 mm long, 0.5–0.7 mm in diameter, straight, densely glandular puberulent, apex slightly curved; anthers triangular, 1.7–1.8 × 1.6–1.8 mm, basifixed, two anthers connivent, not coherent at apex, thecae two, parallel, not confluent at apex, poricidal at the apex, connective not projecting, sparsely puberulent; staminodes absent. Disc absent. Pistil 7.1–7.7 mm long; ovary 2–2.1 mm long, 1.2–1.4 mm in diameter, ovoid or narrowly ovoid, densely pilose and sparsely glandular puberulent, 1-loculed, placentas 2, sometimes 3, parietal, projecting inward, 2-cleft; style 5.1–5.6 mm long, 0.2–0.3 mm in diameter, sparsely glandular puberulent at base, glabrescent above base; stigma 1, terminal, capitate, apex emarginate. Capsule straight in relation to pedicel, 4.6–6 mm long, 1.4–1.6 mm in diameter, oblong to ovoid, sparsely pilose, dehiscing loculicidally to base; valves 2, straight, not twisted. Seeds 0.3–0.4 mm long, ellipsoid to broadly ellipsoid, unappendaged.

Phenology:— Flowering occurs from late April to June. Fruiting occurs from late August to September.

Etymology:— The new taxon is named after the type locality, Panzhou County, China.

Vernacular name:— The Chinese name is “Pán Zhōu Shí Hú Dié” (ȐffibOiḀ).

Distribution and habitat:— Only two populations have been found in Niangniang Mountain, Pugu Town, Panzhou County, Guizhou Province, China. The plants grow on rocks in limestone caves ( Fig. 2 ). The main companion species was Adiantum gravesii Hance (1875: 197) .

Conservation status:— Two populations with approximately 500 mature individuals were found at and around the type locality. The habitats are in villages and threatened by human activities. We visited other sites in Niangniang Mountain several times in the last five years and did not find other populations. Before carrying out further investigations, this species should be assessed as “Data Deficient” (DD), according to the IUCN standards ( IUCN 2012, 2022).

Morphological affinities:— The new taxon is most similar to Petrocosmea henryi ( Fig. 3 ) in having lobed leaf blades, one flower per cyme and straight filaments, but it can be easily distinguished from the latter by the shape and length of the anthers. The new taxon is also similar to P. weiyigangii in sharing the lobed leaf blades, but they are different in the shape of adaxial corolla lip apex and filaments. The detailed morphological comparisons among P. panzhouensis , P. henryi and P. weiyigangii are shown in Table 1 .

It should be noted that when Hemsley described Petrocosmea minor Hemsley (1899 : pl. 2600), he cited two collections, viz., Hancock 428 and A. Henry 9154. Craib examining Hancock’s specimens realized that the original figure of P. minor was drawn from these plants, and not from Henry’s collections, so he described P. henryi with strongly waved leaf blade margin and elongate and sagittate anthers ( Craib 1918). In fact, the collection A. Henry 9154 contained several taxa, including P. henryi and P. minor ( Global Plants 2022) . In 1985, P. henryi was designated as synonymy of P. minor , based on indumentum on filaments ( Wang 1985). In 1996, A. Henry 9154 (E00396425) was labeled and verified as Holotype of P. henryi and Isosyntype of P. minor by Skog and Weitzman. In 2021, P. henryi was reinstated ( Shaw 2021).

Figures

FIGURE 1. Petrocosmea panzhouensis Sheng H.Tang & Tao Peng, sp. nov. A, B flowering plant C adaxial and abaxial surfaces of leaf blade D cymes, and bracts inside and outside (inset) E flower in front view F flower in side view, and calyx lobes outside and inside (inset) G flower in top view H opened corolla with pistil removed, showing stamens, and spots inside the corolla I stamens ventral and dorsal, and dehiscing terminal anther pores (inset) J pistil, cross section of ovary (inset), and red lines showing the shape of placentas K capsules of previous year L seeds of previous year. (Photographs by Sheng-Hu Tang).

FIGURE 2. Habitats of Petrocosmea panzhouensis Sheng H.Tang & Tao Peng, sp. nov. A type locality of P. panzhouensis, growing inside the cave B, C landscape of Niangniang Mountain D, E, F P. panzhouensis in the cave at the the type locality. (Photographs by Sheng-Hu Tang).

FIGURE 3. Holotype of Petrocosmea henryi Craib stored in E (Henry 9154, E00396425), and enlarged flowers (inset) from this specimen, showing its anthers.