Petrocosmea rhombifolia Y.H.Tan & H.B.Ding, 2019

Yang, Bin, Ding, Hong-Bo, Fu, Kai-Cong, Yuan, Yi-Kai, Yang, Han-Yu, Li, Jian-Wu, Zhang, Li-Xia & Tan, Yun-Hong, 2019, Four new species of Gesneriaceae from Yunnan, Southwest China, PhytoKeys 130, pp. 183-203 : 183

1. Petrocosmea rhombifolia Y.H.Tan & H.B.Ding sp. nov. Figures 1 , 2

Diagnosis.

Petrocosmea rhombifolia is similar to P. rosettifolia , but differs from the latter in having rhombic leaf blades (vs. broadly ovate to orbicular or broadly elliptic) and much longer petiole to 15 cm long (vs. to 4 cm long); the flowers have upper white lip (vs. purple-blue flowers throughout), corolla adaxial lip 14-15 × 9-10 mm (vs. ca. 5 mm), abaxial lip 27-28 × 12-14 mm (vs. ca. 7-8 × 6-8 mm), and flowering March-April (vs. October).

Type.

CHINA. Yunnan Province: Lancang County, Laba village, 22°36'42.52"N, 99°42'57.10"E, a.s.l. 1900 m, 1 April 2017, Y.H. Tan & H.B. Ding, T0119 (holotype: HITBC!).

Description.

Perennial herb with short rhizomatous stem and crowded fibrous roots. Leaves 14 to 25, all in basal rosette; petioles 0.5-15 cm long, densely white pubescent to sericeous; leaf blades ovate or ovate to rhombic, 1.5-5.3 × 1.3-2.8 cm, rounded or cuneate at base, with nearly entire or slightly repand margins and acute or obtuse apex, densely pubescent to sericeous on both surfaces; lateral veins abaxially conspicuous, 2-3 on each side. Inflorescences 1-flowered, 4-6 cm long; Peduncles 2.5-3.2 cm long, pedicels 1.6-2.0 cm, densely pubescent to sericeous; Bracts 2, opposite, subulate, 2-3 mm. Calyx actinomorphic, equally divided into 5 lobes from base, lobes lanceolate, 4-5 mm, sparsely pubescent inside, densely sericeous outside. Corolla light blue, sparsely pubescent to puberulous outside, sparsely puberulent or subglabrous inside; tube 5-6 mm, sometimes with 2 ovate brown spots inside below the stamens; throat light blue or whitish blue with 2 oblong deep blue blotches; adaxial lip ca. 14-15 × 9-10 mm, semi-orbicular, light blue or whitish blue, distinctly 2-lobed, lobes reflexed, with rounded apex and repand margin; abaxial lip ca. 27-28 × 12-14 mm, blue, 3-lobed to or over the middle, with sub-orbicular to obovate lobes, lobes with rounded apex and repand to slightly crenate margin. Stamens 2, about 6 mm long, adnate to the base of the corolla tube; filaments about 3 mm long, sparsely pubescent; anthers ovate, about 3 mm long, dehiscence poricidal, glabrous, dorsifixed, coherent at apex. Staminodes 3, ca. 2 mm, adnate to the corolla tube at the base, sub-glabrous. Pistil ca. 1.1 cm; ovary densely villous, oblate, ca. 3 mm; style ca. 8 mm, sparsely pubescent near base; stigma capitate. Fruit a short capsule, 8-10 mm long.

Etymology.

The new species is named after its rhombic leaf blades.

Vernacular name.

Chinese mandarin: ling ye shi hu die (菱叶石蝴蝶).

Phenology.

Flowering March-May and fruiting April-June.

Distribution and habitat.

Petrocosmea rhombifolia grows on moist rock faces in limestone forest, at elevation ca. 1900 m in Laba, Lancang County.

Conservation status.

Petrocosmea rhombifolia has hitherto only been found at its type locality in Laba, Lancang County. There is very limited information about its natural distribution; a further detailed investigation of the same habitats will help to identify additional populations and individuals of this new species. The lack of sufficient data currently does not allow a risk evaluation and the species can be regarded at present as Data Deficient (DD) according to the IUCN Red List Categories and Criteria ( IUCN 2012).

Note.

Petrocosmea rhombifolia has ovate leaf blades with pubescence on the surfaces that are similar to P. rosettifolia , but mainly different from the leaf blade and flower characters. A comparative list of diagnostic characters of the new species and P. rosettifolia is given in Table 1 .

Figures

Figure 1. Petrocosmea rhombifolia Y. H. Tan & H. B. Ding, sp. nov. A, B Habit C, D flower in front view E flower in side view F flower in back view G flower H dissected corolla (showing pistil and stamens) I cyme J calyx in abaxial view K leaves. Photographed by H. B. Ding.

Figure 2. Petrocosmea rhombifolia Y. H. Tan & H. B. Ding, sp. nov. A Habit B calyx in adaxial view C leaf blade in abaxial view D pedicel with calyx and pistil E anthers F corolla in front view G dissected corolla. Drawn by Zhen-Meng Yang.