Justicia tiandengensis Y. Nong & G. Y. Wei, 2025

Nong, You, Feng, Bin, Hu, Qi-Min, Li, Ying-Jing, Wei, Gui-Yuan, Ji, Xing-Yun & Lai, Ke-Dao, 2025, Justicia tiandengensis (Acanthaceae), a new species from Guangxi, China, PhytoKeys 260, pp. 63-74 : 63-74

Justicia tiandengensis Y. Nong & G. Y. Wei sp. nov.

Figs 1 , 2 , 3 , 4 Chinese name: “ tiān děng jué chuáng ” (天等爵床 )

Diagnosis.

Justicia tiandengensis is most similar to J. leptostachya , but it can be easily distinguished by its stem terete, glabrous (vs. 4 – angled, sulcate, bifariously pubescent), its leaf blade oblong, thickly papery (vs. ovate, thinly papery); its calyx 2–3 mm long, outside pubescent (vs. ca. 6 mm long, margin ciliate); and its ovary and style pubescent (vs. glabrous).

Type.

China - Guangxi • Y Nong et al. 051210 ( GXMI); Tiandeng County; 23°57'26"N, 107°04'53"E; alt. 410 m; 3 Mar. 2025; fl • Y Nong et al. NY 2025050601 ( GXMI, IBK); Tiandeng County; 23°57'26"N, 107°04'53"E; alt. 410 m; 6 May 2025; fl, fr .

Description

. Herbs to 40 cm tall. Stems green, terete, basally prostrate and rooting at nodes, then erect, glabrous. Petiole 1–4 cm, not winged, glabrous; leaf blade oblong, 5–12 × 1.7–3.5 cm, thickly papery, both surfaces glabrous, midrib sunken adaxially and prominently raised abaxially; lateral veins are approximately 5–7 pairs, slightly raised abaxially, base cuneate, decurrent, margin entire, revolute when dry, apex acute. Inflorescences green, erect, terminal, racemose or panicle, branched or unbranched; rachis puberulent, with 2–4 flowers per node; pedicels very short, ca. 0.5 mm long; bracts ovate, elliptic, or lanceolate, green, ca. 1 mm long, abaxially puberulent; bracteoles lanceolate to rarely triangular, 0.5 mm long, abaxially puberulent. Flowers suberect. Calyx 5 - lobed almost to base, narrowly linear, 2–3 mm long, green, pubescent outside, clasping the corolla tube, apex acute. Corolla yellow, 6–7 mm; lower lip ca. 4 mm, 3 - lobed, lobes ovate and ca. 0.5 × 0.5 mm; upper lip subtriangular, ca. 3 mm, 2 - lobed. Staminal filaments ca. 5 mm, glabrous; anther thecae linear, ca. 1 mm, lower one spurred at base. Ovary ellipsoid, ca. 1 mm, pubescent, ovules 1 or 2 per locule; style ca. 5 mm, pubescent. Capsule clavate, 10–12 mm long, puberulent, base solid, 3 or 4 - seeded. Seeds broadly ovate, compressed, yellowish-brown, 2–3 mm in diameter, testa tuberculate.

Etymology.

The specific epithet “ tiandengensis ” refers to the type locality, Tiandeng County (天等县), which is situated in southwest Guangxi, southwest China.

Distribution and habit.

Currently, Justicia tiandengensis is known only from the southwest of Guangxi, China (Fig. 5 ). It has been mainly found in a karst cave at an elevation of about 410 m.

IUCN Red List Category.

Due to limited available data, the conservation status of this new species cannot be definitively assessed. Following IUCN criteria ( IUCN 2022), it is currently classified as Data Deficient (DD) pending further research and information.

Figures

Figure 1. ML tree of the new species Justicia tiandengensis sp. nov. and its related species, based on the ITS dataset. Bootstrap values of the maximum likelihood are shown along the branches.

Figure 2. Line drawing of Justicia tiandengensis Y. Nong & G. Y. Wei. A. Flowering plant; B. Flower (lateral view); C. Flower (front view); D. Capsule; E. Capsule dissection; F. Flower dissection (showing lower anther thecae spurred at base); G. Ovary and style (drawn by Xin-cheng Qu).

Figure 3. Justicia tiandengensis Y. Nong & G. Y. Wei. A. Habitat; B. Flowering plant; C. Stem and node; D. Leaves (abaxially and adaxially); E. Flower (lateral view); F. Flower (front view, showing only lower anther theca spurred at base); G. Flower (dissected view); H. Ovary and style; I. Capsule and seeds; J. Pollen grain (Edited by Y. Nong).

Figure 4. The type specimen of Justicia tiandengensis Y. Nong & G. Y. Wei.

Figure 5. The distribution of Justicia tiandengensis Y. Nong & G. Y. Wei (red circle) and J. leptostachya Hemsl. (green circle) in Guangxi (blue triangle), China.