Gigantochloa multifloscula sp. nov. (họ Lúa: phân họ Tre), một loài mới ở Việt Nam

The genus Gigantochloa Kurz ex Munro, 1868 was established by Kurz ex Munro in 1868, based on Gigantochloa atter Kurz and currently consists of about 30 species, distributed in South and Southeast Asia, with the majority of the species in India, Malaysia, Indonesia, Philippines, Thailand, Laos and Vietnam (Ohrnberger 1999; Li & Stapleton 2006). This genus is characterized with respect to the other genera of the subtribe Bambusineae Presl by its spikelets with a sterile terminal floret with lemma only, sessile, lodicules absent, filaments joined to form a tube, ovary with hairs at top, stigma 1 (Munro 1868; Gamble 1896; Holttum 1946, 1956, 1958; Wong 1995; Dransfield & Widjaja 1995; Widjaja 1997; Li & Stapleton 2006). In Vietnam, the genus Gigantochloa was  taxonomically studied by several authors (Camus & Camus 1923; Ho 2000), and currently consists of about 8 species (Pham 2000). Among these taxa, Gigantochloa sp. whose vernacular name is “mum” was described by Pham (2000) in An Illustrated Flora of Vietnam based on specimens in Paris (P). In distinguishing among related taxa, Pham discovered that Gigantochloa sp. has in common such character as the presence of pseudospikelets consisting of 4-5 perfect flowers. Otherwise, we checked all the specimens of this species that have been collected in Vietnam during the years 1865-1954 and stored in P such as: Pierre 6665 (1865), Poilane 17328 (1930), Schmid 1506 (1953), 1828 (1954); none of them was designated as type. Thus the brief description given in this book was still inadequate for assessment of which species Ho intended to name (Ho 2000), because he did not cite any holotype, Latin diagnosis and did not provide anymore for that species.

In May 2005 and August 2008, expeditions to Da Huoai and Da Teh districts (Lam Dong Province), Chua Chan Mountain (Dong Nai Province), Southern Vietnam, the localities of the specimens collected by Pierre, Poilane and Schmid, were undertaken by us. Some gathered specimens matched the description and illustration of Gigantochloa sp. in the structure and position of their spikelets. The present paper is a description of this interesting species, including fresh materials and sheets kept in Paris (P).

Typus

Vietnam. Prov. Dong Nai, Cat Tien, Km 145 on the road Saigon to Dalat, fl. 25.I.1953, Schmid 1506 (holo-, P!). Paratypus. — Vietnam. Prov. Dong Nai, Cat Tien, Km 140 on the road Saigon to Dalat, fl. 15.V.2005, 150 m asl, H.N.Nguyen, V.T.Tran 52005460 (Herbarium of the Forest Science Institute of Vietnam – FSIV!).

Other Material Examined

Vietnam. Cochinchina, Pro. Bien Hoa, Chua Chan Moutain, Pro. Bien Hoa, Cochinchine, IX.1865, Pierre 6665. — Cochinchine, Bara Mountain, fl. 23.VIII.1930, Poilane 17328 (P). — Km 155 on the road Saigon-Dalat, 200 m als, fl. 14.I.1954, Schmid1828. — Prov. Lam Dong, Da Teh District, Da Teh Lake, fl. VIII.2008, new shoots are developed between June-August, V.T.Tran 82008461 (FSIV).

Distribution habitat and local uses

Gigantochloa multifloscula sp. nov. was found in several populations. They grow in the degraded natural forest in valleys and mountain gorges, between 100 and 800 m asl, southern Vietnam. This species is of considerable importance to the local people. Its culms are used for making handicrafts and household tools. The shoots are edible.

Etymology

The specific epithet refers to the spikelet comprising 4-5 florets.

Gigantochloa multifloscula H.N.Nguyen, N.Xia & V.T.Tran, sp. nov.
A, culm; B, culm sheath; C, section of leafy branch; D, section of flowering branch; E, spikelet; F, florets; G, lemma; H, dorsal (right) & ventral (left) views of palea; I, sterile terminal floret with lemma only; J, stamen; K, ovary. A-C, drawn from paratype; D-K, drawn from type. Scale bars: A, 2 cm; B, 3 cm; C, 3.5 cm; D, E, 2.5 cm; G, 1.5 mm; H, 0.6 mm; I, 0.5 cm; J, 0.8 mm.

Field photographs of Gigantochloa multifloscula H.N.Nguyen, N.Xia & V.T.Tran, sp. nov.
A-E, holotype (Schmid 1506); B, lemma; C, dorsal & ventral views of palea; D, sterile terminal floret with lemma only; E, ovary; F, clump; G, section of culm bearing culm sheaths; H, paratype (H.N.Nguyen, V.T.Tran 52005460), culm sheath; I, flowering branches; J, section of flowering branches; K, spikelet; L, M, florets; N, stamens; O, filaments fused into a tube.

Hoang Nghia NGUYEN
Nianhe XIA
Van Tien TRAN