Rungia fangdingiana Z. L. Lin, Y. F. Deng & Y. H. Tan, 2022

Lin, Zhe-Li, Tan, Yun-Hong, Huang, Yun-Feng & Deng, Yun-Fei, 2022, Rungia fangdingiana (Acanthaceae), a new species from Guangxi, China, PhytoKeys 202, pp. 97-105 : 97

Rungia fangdingiana Z. L. Lin, Y. F. Deng & Y. H. Tan sp. nov.

Figs 1 , 2 , 3

Type.

China. Guangxi Province: Napo County, Baisheng Xiang, Nongmiao Cun , 965 m elev., 24 July 2015, Y. H. Tan et al. 4366 (holotype: IBSC!; isotypes: IBSC!, HITBC!) .

Diagnosis.

Similar to Rungia sinothailandica and R. burmanica , but is readily distinguishable by the flat, entire bract margin (vs. crispate, tawny membranous bract margin in R. sinothailandica , and crenulate bract margin in R. burmanica ), glabrous calyx and capsule (vs. puberulous calyx and puberulent capsule in R. sinothailandica and R. burmanica ), pale yellow corolla with red stripes, upper lip unlobed (vs. white corolla with red stripes, upper lip 2-lobed in R. sinothailandica , and white corolla with purple dotted stripes, upper lip unlobed in R. burmanica ). A detailed comparison of the three species is given in Table 1 .

Description.

Perennial erect herb, about 1 m tall. Stem terete, glabrous. Leaves usually anisophyllous; petiole 1-2 cm long, glabrous; blade elliptic, 5-15 × 2-5 cm, base cuneate, margin entire, apex attenuate or acute, both surfaces glabrous, but densely covered with linear cystoliths, secondary veins 5-10 on each side of mid-vein. Inflorescence of terminal and axillary spikes, 3-7 cm long; peduncle 1-2 cm long, glabrous. Bracts 4-ranked, only two ranks fertile; sterile bracts ovate, oblique at base, 1.4-1.6 × 0.9-1.1 cm, green, glabrous, both surfaces covered with linear cystoliths, lacking hyaline margins; fertile bracts rhombic to elliptic, symmetrical, 1.3-1.5 × 0.9-1.1 cm, green, glabrous, both surfaces covered with linear cystoliths, membranous hyaline margin flat, 0-0.5 mm wide. Bracteoles elliptic, 1.0-1.1 × 0.3-0.4 cm, green, glabrous, abaxial surface covered with linear cystoliths, membranous hyaline margin flat, sometimes slightly puberulent at margin, ca. 1 mm wide. Calyx 5-lobed almost to the base, lobes linear, equal, 8-8.5 × 0.9-1.1 mm, glabrous. Corolla bilabiate, glabrous, ca. 1.5 cm long, pale yellow with red stripes on lower lip and throat; tube cylindrical at base and enlarged abruptly in throat, ca. 1 cm long; upper lip unlobed, attenuate at apex; lower lip 3-lobed, lobes rounded at apex. Stamens 2, 4.5-5 mm long, inserted at base of corolla throat, base adnate with corolla tube; filaments glabrous; anthers bithecous, superposed, ca. 3 mm long, thecae ovoid, glabrous, lacking a conspicuous basal spur. Pollen prolate, 35.99 (33.2-38.5) × 18.94 (15.7-21.6) μm, with P/E = 1.90, tricolporate, with one row of insulae on each side of aperture, exine ornamentation reticulate. Ovary glabrous, ca. 1.5 mm long; style slightly puberulent at base and middle part, ca. 1 cm long; stigma minutely 2-lobed. Capsule clavate, stipitate, glabrous, 1.1-1.2 × 0.3-0.35 cm. Seeds suborbicular to elliptic, compressed, dark brown, 2.5-3.5 × 2-2.5 mm, surface covered with brain-like verrucae.

Phenology.

It was observed with flower and fruit at the same time from October to December and June to July.

Etymology.

This new species is named in honor of Mr. Fang Ding (1924-2017) for his contributions to studies of the family Acanthaceae from Guangxi, China. He was the co-author of the account of family Acanthaceae for "Flora of Guangxi" and has published 37 new taxa of Acanthaceae from Guangxi ( Fang and Deng 2017).

Vernacular name.

方鼎孩儿草 (Chinese pinyin: fāng dǐng hái ér cǎo).

Distribution and habitat.

This species is currently known from three localities in Napo County of Guangxi Province. It grows close to stream sides in evergreen forest on limestone at elevations of 600 to 1200 m.

Conservation status.

During the field investigations, only three scattered populations of Rungia fangdingiana were discovered, which all grow in forest on limestone in Napo county. Because of its narrow distribution (extent of occurrence <20,000 km2), limited locations (<10), with an estimated population size of <1000 mature individuals, and there is continuing decline estimated in quality of habitat and number of locations due to human activities as the localities are not protected, it should be assessed as Vulnerable (VU) (B1ab(iii)(iv)) according to the IUCN Red List Categories and Criteria ( IUCN 2012, 2022). However, the area around the localities of this new species is poorly investigated, and further rigorous investigations are necessary to confirm this assessment.

Additional specimens examined

(paratypes): China. Guangxi, Napo County: Nonghe Cun, on the way from Nonghe Cun to Tongziwan Power Station , on the rocks near stream-sides, 674 m elev., 11 December 2019, Y. F. Deng et al. 29030 (IBSC!); Napo County , in limestone forest, 1200 m elev., 24 October 2002, H. Wang 6616 (HITBC!, PE!) .

Figures

Figure 1. Photographs of Rungia fangdingiana sp. nov. A habit B spike (abaxial view showing the sterile bracts) C spike (adaxial view showing the fertile bracts and fruits) D spike (adaxial view showing the fertile bracts and corolla) E corolla F, G adaxial view of leaf blade (showing the linear cystoliths) A-E by Yun-Hong Tan, F, G by Zhe-Li Lin.

Figure 2. Fruit, seed and pollen morphology of Rungia fangdingiana sp. nov. A dehiscent capsule (showing the rising placenta and seeds) B seed C seed testa (SEM) D detail of the verrucae of seed testa (SEM) E interapertural view of pollen grain F apertural view of pollen grain. Photos by Zhe-Li Lin.

Figure 3. Line drawings of Rungia fangdingiana sp. nov. A flowering branch B spike (abaxial view showing the sterile bracts) C spike (adaxial view showing the fertile bracts and corolla) D sterile bract E fertile bract F bracteole (abaxial view) G bracteole (adaxial view) H calyx I corolla J opened corolla K pistil L stigma M stamen (adaxial view) N stamen (abaxial view) O dehiscent capsule (showing the rising placenta and seeds) P seed. Drawn by Yun-Xiao Liu.