Rungia hirpex Benoist (1930: 149)

Lin, Zhe-Li, Xu, Chao & Deng, Yun-Fei, 2016, The rediscovery of Rungia hirpex (Acanthaceae) in Yunnan, China, Phytotaxa 289 (2), pp. 158-166 : 159-162

Rungia hirpex Benoist (1930: 149) ( Figs 1 & 2 )

Type :— CHINA. Yunnan: Yanjin County, “vallee du Lao oua tan”, 600 m elev., E. E. Maire s.n. (lectotype P00719985 !, isolectotypes P00719986 !, P00719987 !; designated here). Available at: http://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.p00719985 .

Perennial prostrate herbs, about 30–50 cm long; stems terete, bifariousely pubescent, basally rooting at nodes. Leaves opposite, isophyllous or slightly anisophyllous; petiole 1–2 cm long, pubescent; leaf blade ovate to elliptic, 5–10 × 3–5 cm, base cuneate or oblique, margin entire, apex acuminate, adaxially densely covered with linear cystoliths and pubescent on veins, abaxially densely covered with linear cystoliths and sparsely pubescent on veins, secondary veins 5–7 on each side of midvein, camptodromous. Spikes terminal and axillary, 4–10 cm long; peduncle 0.5–2 cm long, pubescent, rachis pubescent. Bracts 4-ranked, only 2 ranks fertile; sterile bracts linear, 11–12 × 1.5–2 mm, green, margin hyaline, membranous for ca. 0.2 mm in width, ciliate; fertile bracts linear, 10–11 × 2–2.5 mm, green, margin hyaline, membranous for ca. 0.5 mm in width, ciliate. Bracteoles cymbiform, ca. 7 × 3 mm, light green, margin hyaline, membranous for ca. 0.8 mm in width, ciliate. Calyx 5-lobed almost to base, lobes triangular-lanceolate, ca. 5 × 1 mm, glabrous. Corolla bilabiate, ca. 1.5 cm long, blue, basal tube cylindrical, about 10 mm long, glabrous; upper lip slightly 2-lobed, lobes acute at apex, glabrous, lower lip 3-lobed, lobes truncate at apex, outer surface pubescent. Stamens 2, ca. 4 mm long, inserted at base of corolla throat, base adnate with corolla tube; filaments glabrous; anthers bithecous, superposed, thecae ovoid, upper one pubescent, lower one glabrous, with a conspicuous spur at the base. Disk annular. Ovary glabrous, ca. 1 mm long, 2-loculed, 2 ovules per locule; style ca. 1.1 cm long, thinly puberulent; stigma minutely 2-lobed. Capsule oblong-ovoid, glabrous, ca. 7 × 3 mm. Seeds suborbicular, compressed, brown to dark brown, ca. 1.71 × 1.47 mm.

Distribution, habitat and phenology: — Rungia hirpex is endemic to Northeast Yunnan, China ( Fig. 3 ). The species grows in moist forest by roadsides at elevations of 400–600 m; it has been observed in flower from August to October and in fruit from September to November.

Additional specimens examined: — CHINA. Yunnan: Daguan County, Shoushan Xiang , 535 m, 24 September 2015, Z. L. Lin & X. Q. Tian L15092409 ( IBSC!) ; Yanjin County, near Yanjin north railway station, 400 m, 24 September 2015, Z. L. Lin & X. Q. Tian L15092401 ( IBSC!) .

Conservation status: —Nowadays, R. hirpex is only known from two localities in Northeast Yunnan, China. As the two populations are growing on roadsides which form an unstable habitat due to human activities, we assume that there is a risk of habitat loss and extent of ocurrence, so this species should be accessed as Endangered (EN) according to the IUCN Red List Criteria (IUCN 2012). But it is expected to be found in other areas and further field investigation is in need. Therefore, we prefer to consider it as Data Deficient (DD) currently.

Notes: —Eight species of Rungia are recorded in Yunnan Province (Hu et al. 2011).Amongst these, Rungia hirpex grows at a more northerly latitude in Northeast Yunnan, while the other species except the widespread species, R. pectinata (Linnaeus 1756: 3) Nees von Esenbeck (1847: 470) and R. stolonifera Clarke (1885: 547) , are distributed in South Yunnan.

Rungia hirpex is unique in Chinese Rungia because of its distinct distribution and linear bracts. This species resembles R. taiwanensis Yamazaki (1968: 61) and R. chinensis Bentham (1861: 266) in its prostrate herbaceous habit, ovate to elliptic leaves and similar inflorescences, but they can be distinguished from each other by their bracts, corollas and distribution. The differences between these three species are shown in table 1.

Figures

FIGURE 1. Rungia hirpex:A. Habitat.B. Habit. C. Flowers. D. Inflorescence abaxial view showing the sterile bracts (s = sterile bract). E. Inflorescence adaxial view showing the fertile bracts (s = sterile bract; f = fertile bract). F. Dissected flower and fruit (sterile bract, fertile bract, two bracteoles, calyx, corolla, pistil and fruit).

FIGURE 2. Line drawing of Rungia hirpex. A. Sterile bract. B. Fertile bract. C. Bracteole adaxial surface. D. Bracteole abaxial surface. E. Calyx. F. Corolla (opened out). G. Pistil. H. Stigma. I. Corolla. J. Stamen. K. Capsule (dehiscent). L. Capsule. M. Habit. Drawn by Dinghan Cui from Z. L. Lin & X. Q. Tian L15092401.

FIGURE 3. Distribution map of Rungia hirpex.