Elatostema pleiophlebium W.T.Wang & Zeng Y.Wu,, 2011

Wu, Zeng-Yuan, Wang, Wen-Tsai, Wang, Hong & Li, De-Zhu, 2011, Two new species of Elatostema (Urticaceae) from southeast Yunnan, China, PhytoKeys 7, pp. 57-62 : 58-59

Elatostema pleiophlebium W.T.Wang & Zeng Y.Wu, sp. nov. Fig. 1 F–I2A–C

Latin

Ob foliorum nervos laterales plures et capitula staminata 6-bracteata glabra species nova haec est fortasse affinis Elatostema quinquecostato W.T.Wang, quod caulibus strigosis, foliis apice cuspidatis supra hispidis subtus strigosis nervos laterales utrinsecus usque ad 12-14 ferentibus, capituli staminati bracteis duabus exteris dorso 5-costatis et infra apicem breviter corniculatis praeclare differt.

Type.

China. Yunnan, Hekou county, Nanxi village, Sanchahe river, 22°41'4"N, 103°59'26"E, 388 m, 01 Aug. 2010, Z. Y. Wu 10181 (Holotype: PE!; Isotype: PE!); the same locality, 01 Aug. 2010, Z. Y. Wu 10186 (Paratype: KUN!).

Description.

Perennial herb. Stems erect, 30-50 cm tall, glabrous, unbranched. Stipules narrowly lanceolate or lanceolate, 5-14 × 1.5-3 mm, with cystoliths 0.5-0.7 mm long, apex pungent; leaves shortly petiolate, glabrous, petioles 3-17 mm long; leaf blade chartaceous, obliquely narrowly ovate, broadly oblong or elliptic, 10-20 × 4.5-7.2 cm, glabrous, adaxial surface with 1 broad, interrupted, white stripe along the mid vein, adaxial surface with dense cystoliths, conspicuous, bacilliform, 0.25-0.8 mm long, penninerved, narrow side with (4-) 7-10 lateral nerves, broad side with (5-) 7-11 lateral nerves, base obliquely cuneate, margin denticulate, apex acuminate, shortly acuminate or obtuse. Staminate capitula solitarily axillary, glabrous; peduncle ca. 1.5 mm long; receptacle broadly oblong, ca. 8 × 6 mm; bracts 6, 2-seriate, ovate or narrowly ovate, abaxially above longitudinally 1-ribbed, with rib apex extended into subulate horn-like projections, outer 2 opposite, larger, 4-5 × 9 mm, with apex projection 3 mm long, inner 4 smaller, 4-5 × 5-7 mm, apex projection 1-1.5 mm long; bracteoles membranous, numerous, semihyaline, above brownish, obtrapezoid or navicular, 2-3.2 × 0.6-2 mm, above slightly conduplicate, apex cucullate. Staminate flower buds subsessile, broadly obovoid, ca. 2 mm long, glabrous, apex 4-corniculate. Female flowers and achenes not known.

Ecology.

Elatostema pleiophlebium is a forest understory herb. In the type locality, it occurs on wet ground in forest close to a river where it is associated with Elatostema alnifolium and some species of Musa , Ficus andPiperaceae.

Distribution and conservation status.

Elatostema pleioph lebium is known only from the type locality near the Sanchahe river, Nanxi village, Hekou county, Yunnan. Consequently, it is probably an endemic species. A single population of a few hundred individuals was observed in an area of 1 km2. We believe therefore, that this new species is on the verge of extinction but we do not know if population size is stable or declining. Following the IUCN red list criteria ( IUCN 2011), we propose to classify this species as critically endangered (CR B2ab (iii); C2b).

Similar species.

Elatostema pleiop h lebium is a member of series Nanchuanensia W.T.Wang in sect. Elatostema ( Wang 2011a). Elatostema pleiophlebium is similar to Elatostema quinquecostatum W.T.Wang in having numerous lateral leaf nerves and a staminate capitulum involucre formed of six glabrous bracts. Elatostema quinquecostatum differs from Elatostema pleiophlebium in having stems with strigose hairs, cuspidate leaf apices, hirsute adaxial leaf surface, strigose abaxial leaf surfaces, bearing ca. 12-14 nerves, the outer 2 staminate bracts abaxially longitudinally 5-ribbed and short coniculate below apex ( Wang 1995).

Etymology.

The epithet 'pleiophlebium' refers to the numerous lateral nerves characteristic of the leaves of this species.

Figures

Figure 1. A-E Elatostema malipoense W. T. Wang & Zeng Y. Wu. A Upper part of flowering pistillate stem B pistillate capitulum, seen from below C two pistillate involucral bracts D pistillatate bracteoles and pistillate flower E achene, (based on Z. Y. Wu 10347). F-I Elatostema pleiophlebium W. T. Wang & Zeng Y. Wu. F upper cauline leaf G staminate capitulum H staminate bracteole I staminate bracteoles and staminate flower bud, (based on Z. Y. Wu 10181).

Figure 2. A-C Elatostema pleiophlebium W. T. Wang & Zeng Y. Wu. A Specimen B staminate bracteole C stipule D-G Elatostema malipoense W. T. Wang & Zeng Y. Wu. D pistillate capitulum, seen from below E pistillate involucral bracts F pistillate bracteoles G achenes.