Thismia gongshanensis Hong-Qing Li

Li, Hong-Qing & Bi, Yu-Ke, 2013, A new species of Thismia (Thismiaceae) from Yunnan, China, Phytotaxa 105 (1), pp. 25-28 : 25-27

Thismia gongshanensis Hong-Qing Li & Yu-Ke Bi, sp. nov. ( Fig. 1–2 )

Type:— CHINA. Yunnan: Maku Village , Dulongjiang Town , Gongshan County, 2,275 m, 27 o 41’54.6”N, 98 o 18’15.62”E, 27 June 2008, Li 2008128 (holotype HSNU!; isotype KUN!) .

Thismia gongshanensis most closely resembles T. tuberculata Hatusima (1976: 4) , but differs in having a yellow perianth, free stamens, bicarpelate parietal placentas and 2 simple stigmas.

Herbs with rhizome creeping horizontally, branched, terete, pale brownish, apex whitish, with adventitious roots and buds. Stem white, unbranched, erect, glabrous, ca. 6–10 cm high, 1.8 mm in diameter at anthesis. Leaves 4–7, translucent-whitish, elliptic-lanceolate, alternately scattered along stem, adnate, appressed, entire, scale-like, ca. 4–7 × 2–3 mm, with a single vascular trace, apex obtuse. Bracts 3, ringed, similar to leaves. Flower solitary with 1 mm pedicel. Perianth actinomorphic, 6 lobes in 2 whorls, fused to form a basa tube, which is translucent-yellow, urceolate, densely tuberculate externally, 7.5 mm long, 6.5 mm in diameter, with 12 vertical ribs on the inside of the tuber; upper part of the tube forming a bright yellow annulus (3.6 mm outer diameter); outer (smaller) perianth lobes dark yellow, wide-triangular, 2.2 mm long (excluding appendage) and 2.5 mm wide, radiating outward, with revolute margins, clasping subulate appendages, translucent-white, 7–11 mm long, abaxially; inner perianth lobes yellow, wide-spathulate, 4.5 × 4.0 mm, upper part suborbicular, apically imbricate, arching inward distally and forming a mitre over the perianth chamber, dorsal keel ending in an erect subulate appendage (translucent-yellowish, 10–15 mm long). Stamens 6, 3.4 mm long, hanging down from the inner margin of the annulus separately; filaments yellow, flattened, 1.7 × 0.7 mm; connective elongate, white, apex recurved towards the wall of perianth tube, with a few hairs; individual stamen with two thecae, 1.2 mm long, adaxial, thecae separate. Ovary inferior, obconical, 3.3 mm long, 3.8 mm in diameter; carpels 2, unilocular with two parietal placentas, ovule numerous; style yellowish, cylindrical, hollow, 1.1 mm long, 0.6 mm in diameter; stigmas 2, simple, triangular, yellowish with white apex, 1.8 × 1.4 mm, with abaxial pubescence and basal yellow glands. Fruit and seed not seen.

Distribution:—Known only from the type locality at Maku Village, Dulongjiang Town, Gongshan County, Yunnan Province, China.

Ecology:—This species grows among leaf litter in shady wet bamboo forest. The dominant species is Chimonobambusa Makino (Poaceae) . Other accompanying species include: members of genera Aeschynanthus Jack (Gesneriaceae) , Agapetes D.Don ex G.Don (Ericaceae) , Amomum Roxb. (Zingiberaceae) , Balanophora J.R.Forst. & G.Forst. (Balanophoraceae) , Beccarinda Kuntze (Gesneriaceae) , Curculigo Gaertn. (Hypoxidaceae) , Monotropa L. ( Ericaceae ) and Myrmechis (Lindl.) Blume (Orchidaceae) . The mitriform perianth suggests myophily ( Stone 1980), and a small dipteran species was found visiting T. gongshanensis at the time of collection.

Discussion:— Thismia gongshanensis most closely resembles T. tuberculata , which was classified in sect. Glaziocharis (Taubert) Hatusima (1976: 4) . Both species have spathulate inner perianth lobes that are apically imbricate, arching inward distally and forming a mitre over the perianth chamber (imbricated); both whorls of perianth lobes have relatively long subulate appendages; the outer surface of the perianth tube is densely tuberculate. However, the two species are distinct: T. gongshanensis has longer stems (ca. 6–10 cm) at anthesis; inner tepal appendages are about 10–15mm in length and just a little longer than outer tepal appendages; stamens are separate, pistil composed of 2 simple stigmas and 2 parietal placentas; and perianth is yellow. However, T. tuberculata has a shorter stem (ca. 3–4 cm) at anthesis; inner tepal appendages are up to ca. 15–20 mm in length and much longer than the outer tepal appendages; every pair of adjacent stamens is almost adnate; pistil is composed of 3 broadly triquetrous-ovate or capitate stigmas and 3 parietal placentas; the perianth is whitish.

Etymology:—The name of the species was chosen for the place where it was collected. Maku village is in the Dulong River watershed of Gongshan County, northwestern Yunnan, China, neighboring Burma in the west. Its Chinese name should be spelled “gongshan shui yu bei ()”.

Note s:—It has been stated that Thismia has 3 carpels and 3 placentas, with 3 simple or 3 bilobate stigmas or 1 capitate stigma ( Jonker 1938, Maas et al. 1986). However, T. gongshanensis has 2 carpels and 2 placentas, with 2 simple stigmas; these character states are possibly derived. Thus, we keep the sectional position unplaced temporarily.

Figures

FIGURE 1. Morphology of Thismia gongshanensis. A. Habit. B. Magnified flower. C. Dissected flower, showing stamens, style and stigmas. D. Flower from holotype.

FIGURE 2. Diagrammatic drawing of Thismia gongshanensis. E. Flowering plant. F. Floral diagram. G. Dissected flower. H. Perianth-lobes with appendages. I. Imbricate inner tepals. J. Longitudinal section of ovary. K. Cross section of ovary. L. Stamen seen from adaxial and side.