Elatostema celingense W.T.Wang, Y.G.Wei & A.K.Monro, 2011

Wei, Y. G., Monro, A. K. & Wang, W. T., 2011, Additions to the Flora of China: seven new species of Elatostema (Urticaceae) from the karst landscapes of Guangxi and Yunnan, Phytotaxa 29, pp. 1-27 : 4-7

Elatostema celingense W.T.Wang, Y.G.Wei & A.K.Monro , sp. nov. ( Fig. 2 & 3 )

Elatostemo backeri similis sed caulibus et stipulisque minoribus, bractus principalis receptaculum staminalibus panduratus lobatus, differt.

Type:— CHINA. Guangxi: Hechi City, Celing Town, Laba Village , N 24°51'17.7" E 107° 44'11.4", 550 m, 7 May 2010, A. K. Monro & Y. G. Wei 6621 (holotype IBK, isotypes BM, MO, PE). Figure 9 A–H .

Perennial herb, terrestrial, monoecious. Not tuber forming but callous forming, callous ca 10 × 13 mm, brown. Stems 110–200 × 0.675 –1.500 mm, decumbent, not succulent, dark green, drying sulcate, densely pubescent with two classes of hairs, major hairs 1.25–1.50, weakly curved to crooked, erect, brown towards the base, minor hairs 0.375 –0.500 mm, weakly curved to straight, appressed, ascendent, borne in clusters of 2 or 3, internodes 11–18 mm. Stipules 2 at each node, caducous, 2.0– 2.5 mm, lanceolate, sparsely pubescent. Leaves distichous, alternate, terminal pair of leaves subopposite, subsequent leaves subequal, the major leaves subsessile, petioles 0.75–1.50 × 0.5 mm, densely pubescent, with two classes of hairs, major hairs 0.75–1.25, erect to weakly appressed, ascendent, minor hairs 0.250 –0.375 mm, weakly curved, appressed, borne in clusters of 2 or 3; the major laminae 8–52 × 7–16 mm, length:width ratio 1:1.1–3.3, asymmetrically ovate/ elliptic, obovate/elliptic or broadly ovate, membranous, 3-nerved, the secondary nerves (3–)4–6 pairs, 45–60° to the midrib; upper surface drying dark green-brown, sparsely pubescent, the hairs 1.25–1.50 mm, weakly curved, appressed, ascendent, the base of the hair brown, cystoliths densely scattered, bacilliform to fusiform, 0.375 –0.500 mm; lower surface drying green-brown, densely pubescent, the hairs 0.675 –1.250 mm, weakly curved, appressed, ascendent, the base of the hair brown, cystoliths sparsely scattered, bacilliform, 0.37 mm; base asymmetrical, cuneate/acute, decurrent/acute; margins serrate to denticulate, the teeth spaced 3–4 mm apart; apex acute to subacuminate. Staminate and pistillate inflorescences borne on the same or separate stems. Staminate inflorescences solitary, 3.5–5.0 mm, bearing 3–8 flowers in a pedunculate receptacle; peduncle 0.675 –1.000 × 0.375 –0.500 mm, pubescent, subtended by 1 bract; bract 0.75 mm, ovate; receptacle 2.5–4.0 × 3.5–4.5 mm, oval to suborbicular, not lobed or inconspicuously so, sparsely pubescent and brown glandular, white and green above, green below, subtended by marginal bracts, the bracts unequal, major bract subtending the receptacle, minor bracts marginal to each quarter of the receptacle, major bracts 1(2), 5–7 mm, pandurate appearing bilobate or acuminate, with four keel-shaped lobulae, white and green, minor bracts 3–6, 2.5 mm, lobulate, the lobes obovate with a dorsal thickening and subapically corniculate, pale green. Staminate flowers 1.0–1.5 × 1.0 mm immediately prior to anthesis, white, pedicellate, bracteolate; pedicel 0.25 mm, glabrous; bracteoles 2, unequal, major bracteoles 1.25 mm, oblong or obovate, the apex ciliate, minor bracteoles 0.5 mm, oblong or obovate, the apex ciliate; tepals 4, the subapical appendage 0.500 – 0.675 mm, corniculate. Pistillate inflorescence solitary, 1.5–2.0 mm, bearing ca 30 flowers in a pedunculate receptacle; peduncle 0.75–1.00 × 0.5 mm, glabrous, ebracteate?; receptacle 1.5–2.0 × 1.5–2.5 mm, sub orbicular to sub quadrate, inconspicuously 2-lobed, pubescent, dark green above, dark green below, subtended by marginal bracts, the bracts unequal, major bracts 4, 1.5 mm, obovate, subapically 1-corniculate, corniculae falcate, borne perpendicular to the axis of the bract and ascendent, green, minor bracts 8, 1.0 mm, elliptic to obovate, apically corniculate, green. Pistillate flowers 0.500 × 0.375 mm at anthesis, pale brown, pedicellate; pedicel 0.25 mm; bracteoles 2, unequal, major bracteole 0.75 mm, obovate with a subapical appendage, minor bracteole 0.5 mm, subulate. Infructescences not seen.

Distribution:—Known only from the type locality in Hechi City, Guangxi, Southwest China where Elatostema celingense is known only from a small cave formed in limestone karst at an elevation of ca 530 m. This species grows towards the cave entrance in 0.2–2.5% daylight (photosynthetically active radiation).

Etymology:— Elatostema celingense is named after the town near the type locality.

Discussion:— Elatostema celingense is most similar to Elatostema backeri Schroeter (1936) from which it can be distinguished based on stem, stipule and staminate receptacle major bract morphology as summarised in the table below:

Conservation status:—A Global Conservation Assessment is presented here based on IUCN methodology (2001, version 3.1). Elatostema celingense is known from a single locality (IUCN criteria D2). At this locality the population of this species comprises ca 10 mature individuals (IUCN criteria D1). The cave in which this species is located is at the edge of agricultural land on a small limestone hill, which, although deforested in the past, appears not to be actively disturbed. Using the IUCN methodology our Global Conservation Assessment for E. celingense is Critically Endangered (CR) based on criteria D1 and D2: population size and number of locations combined with a plausible future threat that could drive this taxon to Extinct in a very short time. Future threats include the use of caves in agriculture to store livestock or cultivate medicinal plants, mining of the limestone hills or tourism.

Figures

FIGURE 2. Elatostema celingense. A. Habit with leaves, stipules and staminate inflorescences visible. B. Staminate inflorescence with marginal receptacle bracts and flowers. C. Staminate receptacle major bract. D. Staminate receptacle minor bract. E. Staminate flower, tepals with subapical appendage visible. F. Filaments and anthers at anthesis. G. Staminate major and minor bracteoles. H. Pistillate receptacle major bract. Monro & Wei 6621, IBK (Illustration by Sun Ying-Bao).

FIGURE 3. Elatostema celingense. A. Habit. B. Staminate inflorescence with major receptacle bracts and flowers visible. C. Pistillate inflorescences. Monro & Wei 6621 (Photo A.K. Monro).

FIGURE 9. Elatostema multicaule. A. Habitat with habit. B. Habit and leaves with pistillate infructescences. C. Base of plant with young shoots. D. Pistillate infructescence viewed from above, achenes visible. E. Pistillate inflorescence viewed from the side, major and minor bracts visible. Monro & Wei 6748 (Photo A.K. Monro).