Spatholirion puluongense (Commelinaceae), a new species endemic to northern Vietnam

Spatholirion Ridley is a small genus of Commelinaceae closely allied to Streptolirion Edgew. With addition of our new plant, the genus comprises 5 species distributed in mainland SE Asia (Larsen & Larsen 1994, 2003; Hong & DeFilipps 2000; Mabberley 2000). Only one species (Spatholirion longifolium Dunn; syn. S. scandens Dunn) was hitherto reported from Vietnam (Herbert 1937; Pham-Hoang Ho 2000). Two of the species of Spatholirion at present known are short climbing herbaceous vines or small scandent, suberect herbs (S. longifolium, S. elegans (Cherfils) C.-Y.Wu), and the other two are acaulescent subrosulate forbs (S. calcicola K.Larsen & S.S.Larsen, S. ornatum Ridley). The newly discovered species strikingly differs from these plants in its life-form. It is a terrestrial, rather large herb with a leafless short plagiotropic rhizome, rooting at the nodes, and ascending erect stems up to 0.5 m tall, bearing large leaves at the apex and subterminal erect inflorescences in the axils of the apical leaves. This plant is quite different from all hitherto known species of this genus and is described here as a new species.

Spatholirion puluongense Aver., sp. nova

Characteres diagnostici. A specie proxima Spatholirio eleganti caule robusto erecto alto (ca 0.5 m) nec non foliis glabris vel subglabris differt. Type: Vietnam, Thanh Hoa Prov., Ba Thuoc Distr., Thanh Son Municipality, middle part of the Pu Luong Range to the W of Long Bong village (20°27'52'' N, 105°07'36'' E). Primary evergreen seasonal broad-leaved closed submontane forest on basalt along main ridge at elev. 1200.1400 m a.s.l. Terrestrial creeping herb up to 0.5 m tall. Flowers pink-violet. Very common. Usual co-dominant of herb forest stratum. 6 October 2003, L. Averyanov, Phan Ke Loc, Do Tien Doan & Nguyen Tien Vinh HAL 3957 (HN, holotype; iso . LE).

Related species. Spatholirion elegans (Cherfils) C.-Y.Wu.

Fig. 1. Spatholirion puluongense:
a . flowering plant; b . inflorescence; c . male flower (two stamens removed), side view; d . stamen;
e . bisexual flower (two stamens removed), side view; f . bisexual flower (with transversal section of ovary), view from above; g . ovary; h, i . rudimentary ovary in male flower, side view and view from above.

Fig. 2. Spatholirion puluongense, the area of discovery.

Perennial creeping herb with short leafless plagiotropic rhizome rooting at the nodes and ascending erect stems up to 0.5 m tall, bearing a paniculate subterminal  inflorescence. Stem commonly unbranched, with internodes 1.2 cm long, green, juicy, shortly pubescent, 2.5.4 mm broad, with 8.11 alternate, spirally arranged petiolate leaves, reduced in size toward the apex. Leaves 12.15 cm long, bright green on both sides; leaf blade simple, entire, elliptic to broadly  elliptic, acuminate, 8.11 cm long, 3.4 cm wide, glabrous on both sides or with sparse short insignificant hairs at the base, narrowing at the base into narrow petiole 1.3 cm long, 1.5.2 mm wide, with short simple and glandular hairs; leaf sheath broad, closed, cup-like, 5.7 mm long, 5.6 mm broad, with dense long simple hairs along the margin. Inflorescence stalk leafopposed, exserted from the mouth of the leaf sheath, 4.6 cm long, 1.5.2 mm broad, with short simple and light pink glandular hairs.Inflorescence rachis light pink-violet, with a basal leaf-like involucral bract broadly ovate to suborbicular and acuminate, glabrous on both sides, ciliated along the margin, 3.4 cm long, 2.2. 2.5 cm wide; rachis bent at the base at a wide angle to the inflorescence stalk, with dense light pink short hairs; basal  cincinnus with more or less erect straight axis, bearing 2.3 large bisexual flowers, the other 5.10 cincinni with only small male flowers (each cincinnus usually with 3 flowers). Flowers sessile or on very short pedicels, pink-purple, actinomorphic, bisexual or male; sepals free, boat-shaped, obovate, galeate at the apex, about 8 mm long, 4.5 mm wide in bisexual flowers and 4.6 mm long, 3.5.2.5 mm wide in male flowers, with dense long pink hairs outside; petals free, glabrous, narrowly lanceolate to broadly linear, with broad flat apex, about 8 mm long, 1.2.1.4 mm wide in bisexual flowers and 4.6 mm long, 0.8.1 mm wide in male flowers. Stamens 6, all fertile, equal, about 8 mm long in bisexual flowers and 6.14 mm long in male flowers; filaments flat in the basal half, densely villose along the lateral margins with yellow to yellowishwhite long hairs, which intertwine forming a short tube; connective broad, hammer-like; anther locules parallel, broadly obliquely obovate, longitudinally dehiscent. Ovary 3-locular, angulate, narrowly obovate, densely hirsute with long hairs, 3.3.5 mm long, 1.5.1.8 mm broad, attenuate at the apex into narrow glabrous style 4.5 mm long terminating in small three-lobed stigma; in male flowers present as a small insignificant 3.locular triangular rudiment 0.2 mm broad. Fruit 3-valved capsule.

Ecology. Primary evergreen seasonal broad-leaved closed submontane wet forests on basalts at 1200.1400 (1500) m a.s.l.

Distribution. Vietnam: Thanh Hoa Province, Pu Luong Range (Fig. 2). Local endemic of the north-eastern part of the North Indochinese floristic province (in the limits of Vietnam).

Etymology. Named after the original locality, Pu Luong Range.

Spatholirion puluongense was discovered in autumn 2003 in the course of field work during a botanical survey of primary vegetation of Pu Luong nature reserve according to Vietnam Conservation Program of Fauna & Flora International. This unusual endemic plant was observed as a regular co-dominant of the herbaceous cover in primary forest understory in the Pu Luong Range at 1200.1500 m.

Numerous mountain ridges, running in north-western Vietnam in the northwest-southeast direction, are usually composed of granite, gneiss, rhiolite, dacites and other related silicate rocks, and different kinds of more or less metamorphosed shale, schist, sandstones, or more or less eroded limestone (Schzeglova 1957; Fridland 1961; Dovzikov 1965a, b; Rundel 1999; Averyanov et al. 2003a, b). Basalts in this area form the only large and significant mountain formation, Pu Luon Range. It forms a large rocky ridge extending from NW to SE, with predominant heights of the main edge of about 1300.1500 m. The range is entirely composed of basalt penetrated by numerous quartzite dykes. It has very steep high slopes with numerous cliffs and cliffy rock outcrops. By its structure and geomorphology, the range is a unique formation in the country where basalts commonly form ancient fields or plateaus covered with thick horizons of deeply weathered material. In this connection, plant communities found on rocky basalt slopes also have a distinctly specific character.

Climate such as associated with high mountains (Nguyen Khanh Van et al. 2000) is typical of the highlands of the Pu Luong Range. The mean annual rainfall here at low elevations is around 3000 mm. The rainy period lasts from May to September with a relatively dry season lasting during winter and early spring. In mountain belts above 1000 m a.s.l. the amount of annual precipitation may be much greater. Frequent drizzle and cloudy mists keep the plant communities at these altitudes permanently humid. Summer is hot and humid with mean temperatures of 22. 25°, but winter is rather cool with minimal temperatures approaching 0°C. Closed evergreen tropical broad-leaved submontane forests are typical of the Pu Luong Range at 1000.1650 m. They grow on black-brown, thick, friable, well-structured soils rich in humus. Trees of the first stratum reach here 30.40 m and typically include such species as:

Acer brevipes Gagnep., Actinodaphne pilosa (Lour.) Merrill, Amentotaxus argotaenia Pilger, A. yunnanensis Li, Anneslea fragrans Wall., Camellia caudata Wall., Carpinus viminea Lindl., Castanopsis acuminatissima A.DC. ex Hance, C. armata (Roxb.) Spach, C. clarkei King ex Hook.f., C. kawakawii Hayata, Cephalotaxus mannii Hook.f., Cinnamomum kunstleri Ridl., Diplopanax vietnamensis Aver. & T.H.Nguyen, Elaeocarpus griffithii (Wight) A.Gray, Exbucklandia populnea (R.Br. ex Griff.) R.W.Brown, E. tonkinensis (H.Lev.) H.T.Chang, Lithocarpus bacgiangensis A.Camus, L. laotica A.Camus, L. lepidocarpus (Hayata) Hayata, L. pseudosundaicus (Hickel & A.Camus) A.Camus, L. rhabdostachyus A.Camus, L. vinhensis A.Camus, Litsea umbellata (Lour.) Merr., Michelia foveolata Merr. ex Dandy, Nageia wallichiana O.Kuntze, Neolitsea polycarpa H.Liu, Quercus chapensis Hickel & A.Camus, Q. chrysocalyx Hickel & A.Camus, Q. rupestris Hickel & A.Camus, Rhodoleia championii Hook., Sloanea tomentosa (Benth.) Rehder & Wilson,

and a number of species of Magnolia L. Some of these trees occasionally reach 2.2.2 m in diameter. Among smaller trees and shrubs of forest understory the most common are:

Acer flabellatum Rehder, A. tonkinense Lecomte, Aleurites moluccana (L.) Willd., Allophyllus cobbe (L.) Raeusch., Archidendron robinsonii (Gagnep.) I.Nielsen, Ardisia pseudocrispa Pit., A. psychotriiphylla Pit., Brassaiopsis glomerulata (Blume) Regel, B. phanrangensis C.B.Shang, Camellia assamica (Masters) H.T.Chang, Cinnamomum ovatum Allen, Daphniphyllum marchandii (H.Lev.) Croizat & Metc., Dichroa febrifuga Lour., Embelia pulchella Mez, Gaultheria semi-infera Airy Shaw, Helicia formosana Hemsl., H. petelotii Merr., Heynea trijuga Roxb., Illicium majus Hook.f. & Thoms., Lasianthus hispidulus Drake, Lyonia chapaënsis (Dop) Merr., Mastixia arborea (Wight) C.B.Clarke, Polygala tonkinensis Chodat, Rhododendron crenulatum Hutch. ex Sleum., Schefflera heptaphylla (L.) Frodin, S. kornasii Grushv. & N.T.Skvortzova, Sorbus granulosa (Bert.) Rehder, Ternstroemia chapaënsis Gagnep.

Numerous vines, lithophytes and epiphytes, particularly orchids and ferns are very typical of the forests of the Pu Luong Range. The terrestrial herbaceous stratum of the forest understory is very rich and includes a great number of herbs and ferns, among which the most common are:

Alocasia macrorhiza Schott, Amischotolype glabrata Hassk., Angiopteris evecta (G.Forst.) Hoffm., Anoectochilus roxburghii (Wall.) Lindl., Ardisia pseudocrispa Pit., A. psychotriiphylla Pit., Asplenium unilaterale Lam., Begonia baviensis Gagnep., B. handelii Irmsch., Calanthe alismifolia Lindl., C. densiflora Lindl., C. triplicata (Willem.) Ames, Cephalantheropsis obcordata (Lindl.) Ormerod, Colysis digitata (Baker) Ching, C. elliptica Ching, C. pothifolia (D.Don) C.Presl, C. pteropus (Blume) Bosman, Cornopteris decurrenti-alata (Hook.) Nakai, Curculigo capitulata (Lour.) O.Kuntze, Cymbidium ensifolium (L.) Sw., C. lancifolium Hook.f., C. sinense (Jacks.) Willd., Deparia unifurcata (Baker) Kato, Dianella nemorosa Lam., Diglyphosa evrardii (Gagnep.) Tang & F.-T.Wang, Diplazium dilatatum Blume, D. donianum (Mett.) Tardieu, D. megaphyllum (Baker) H.Christ, D. sorzogonense (C.Presl) C.Presl, Dryopteris polita Rosenst., D. stenolepis (Baker) C.Chr., Goodyera foliosa (Lindl.) Clarke, G. schlechtendaliana Reichenb.f., Laportea bulbifera (Siebold & Zucc.) Wedd., Leptostachya wallichii Nees, Microlepia hancei Prantl, M. speluncae (L.) T.Moore, Microsorum hymenodes (Kuntze) Ching, Mycetia balansae Drake, Neocheiropteris phyllomanes (H.Christ) Ching, Paris polyphylla Sm., Plagiogyria adnata (Blume) Bedd., Podophyllum tonkinense Gagnep., Polygonatum kingianum Coll. & Hemsl., P. odoratum (Mill.) Druce, Polystichum biaristatum (Blume) T.Moore, P. chingae Ching, P. squarrosum (D.Don) Fee, Pteris esquirolii H.Christ, Silvianthus tonkinensis (Gagnep.) Ridsdale, Stachyphrynium placentarium (Lour.) Clausager & Borchs., Streptolirion volubilis Edgew., Tectaria dubia (Bedd.) Ching, Tupistra wattii Hook.f., Viola tonkinensis Gagnep. as well as some species of Alpinia L., Amomum L., Aspidistra Ker-Gawl., Carex L., Elatostema Forst., Mapania Aubl., Ophiopogon Ker-Gawl., Ophiorhiza L., Pilea Lindl., Pollia Thunb. and Strobilanthes Blume.

Regular cover of the herbaceous stratum averages approximately 40.80%. Spatholirion puluongense was observed as a common integral element of the herbaceous cover in several localities along the main edge of Pu Luong Range at elevations of 1200.1500 m. This herb occasionally reaches individual cover of up to 60%, particularly in wet humid woods with tall old bamboos. During field work in autumn 2003, mature adult plants of S. puluongense were mostly observed in flower or flower bud. This species obviously meets its ecological optimum in the studied primary humid forests on rocky basalt. However, it probably has a very limited distribution area and represents the strict plant endemism of the eastern part of the North Indochinese floristic province, the limits of which were outlined in our previous papers (Averyanov et al. 2003a, b).

Acknowledgements

Field studies in Vietnam, the results of which are presented in this paper, were supported and managed by Pu Luong-Cuc Phuong Conservation Project of Fauna & Flora International (FFI), Vietnam Conservation Support Program. Laboratory studies and preparation of the manuscript were funded from FFI and USA National Geographic Society (# 7577-04). We would also like to thank Dr. A. Sennikov for his kind correction of our use of the Latin language.

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Leonid V. Averyanov
Herbarium, Komarov Botanical Institute of the Russian Academy of Sciences
Phan Ke Loc, Do Tien Doan, Nguyen Tien Hiep
Institute of Ecology and Biological Resources of the Vietnam Academy of Sciences and Technology
Komarovia (2005)4:37-42