Yersinochloa nghiana V.T.Tran, 2023

Thai Vinh, Tran, Van Duy, Nong, Thanh Truong, Hoang & Van Tien, Tran, 2023, Yersinochloa nghiana, a new species (Poaceae, Bambusoideae, Bambuseae) from southern Vietnam, PhytoKeys 224, pp. 175-182 : 175

Yersinochloa nghiana V.T.Tran sp. nov.

Figs 1 , 2

Diagnosis.

Yersinnochloa nghiana is morphologically most similar to Y. dalatensis and Cochinchinochloa braiana with culms and branches scrambling or hanging over nearby vegetation or trees, lodicules 3, stamens 6, filaments free, caryopsis oblique, with a relatively thin pericarp. However, Y. nghiana is distinguished from Y. dalatensis by culm nodes with a thick swollen patella (vs. culm nodes without a thick swollen patella), culm-leaves blade erect (vs. reflexed), auricles conspicuous (vs. auricles absent). It also differs from Cochinchinochloa braiana in culm-leaves blade half embracing the internode (vs. culm-leaves blade embracing the entire internode), a terminal vestigial flower absent (vs. a terminal vestigal flower 1), perfect florets 1 (vs. perfect florets 2), anther apices bearing tiny spines (vs. anther absent tiny spines).

Type.

Vietnam. Lam Dong Province, Di Linh District, Brain Mountain , E, 1216 m a.s.l., 11°27'25"N, 108°3'41"E, 10 Sep 2022, V. T. Tran DLU 0463 (holotype DLU!; isotype VNMN!, VTN!) .

Description.

Culms and branches scrambling or hanging over nearby vegetation or trees, 5-10 m tall; internodes 40-80 cm long and 3.5-4.5 cm in diameter; when young, densely covered with appressed white hairs; culm walls 0.8-1.0 mm thick; nodes with a thick swollen patella. Branches several with middle one dominant, elongating. Culm leaves black-purplish, sheath with dense appressed white hairs on the abaxial surface; 25-28 cm long and 10-12 cm wide at base; apex 7-8 cm wide and truncate; margins bearing dense white-brown hairs; leaf blades erect, swollen at the base, tardily deciduous, purple-black, 20-25 × 4-5 cm, abaxially with dense white hairs at the base; auricles conspicuous, 2.0-2.2 × 0.2-0.3 cm; ligule short, ca. 1 mm, entire. Leafy branches bearing 5-6 leaves, foliage leafy branches distichously arranged along its length; foliage leaf blades wedge-shaped, 25-28 × 4.0-4.5 cm, acute or cuneate-obovoid at base, glabrous; veins 15-18 pairs; sheaths with ciliate margins, auricles with dense bristles 3-5 mm long; inner ligule a low rim, ca. 1 mm; pseudo-petiole ca. 5-6 mm length. Inflorescences terminating at leafy branches, indeterminate; pseudo-spikelets typically 2.2-2.0 cm long; each subtended by a prophyllate bud, keeled, with ciliate margins, 2.0-2.2 × 0.6-0.8 mm and consisting of one glume, one perfect floret. Rachilla internode below fertile floret ca. 0.5 cm. Fertile floret 1.0-1.2 × 0.2-0.4 cm; lemma oblong lanceolate, 1.0-1.2 × 0.5-0.6 cm, veins 7-9, at apex acute with 0.2 mm long, margins and adaxial side bearing dense white cilia; palea glabrous, distally obviously grooved, dorsal view showing rachilla extension and a rudimentary floret at apex, 1.0-1.2 × 0.5-0.6 cm, acute at apex, base spirally involute; lodicules 3, obovate or oblong, acute at apex, purple, ca. 0.2-0.3 × 0.1-0.2 mm, with ciliate margins, bifid at base. Stamens 6; filaments free, 1.0-1.2 cm; anther ca. 1 mm, purple, apices bearing 3 tiny spines, ca. 1 mm. Ovary green, glabrous with a long style, 1.2-1.0 cm; stigmas 3, purple; caryopsis oblique, with a relatively thin pericarp, 0.9 -1.0 × 0.1-0.2 cm, with a long style, ca. 1.3 cm.

Distribution and habitat.

Yersinochloa nghiana grows in degraded natural forest in valleys, but is also common along rivers and valleys, between 1100 and 1130 m a.s.l., in Braian Mountain, Di Linh District, Lam Dong Province, Vietnam.

Phenology.

The plants were found flowering in December 2007. New shoots developed in June to August.

Local uses.

Yersinochloa nghiana is of considerable importance to the local people. Its culms are used for making handicrafts and household tools.

Etymology.

The new species is named in honour of Dr. Nguyen Hoang Nghia for his contributions to the bamboo research in Vietnam.

Preliminary conservation status.

The species Yersinochloa nghiana sp. nov. is only known from a single population in Braian Mountain, Di Linh District, Lam Dong Province, Vietnam. This single population has no more than 500 mature clumps, all growing in degraded natural forests in valleys, but is also common along rivers and valleys. According to IUCN Red List Categories and Criteria ( IUCN 2022), the species is classified as data deficient (DD) and it needs more surveys.

Figures

Figure 1. Yersinochloa nghiana V. T. Tran: A habitat B clump C, D shoots E culm leaf (dorsal view) F, G auricles H culm leaf swollen at the base I leafy branch J, K section of leafy branch L branches several with middle one dominant. Photos by Tran Van Tien from type locality.

Figure 2. Yersinochloa nghiana V. T. Tran: A-C inflorescence terminating at leafy branches D, E pseudo-spikelets F, G perfect florets H rachilla internode I, J prophyllate bud keeled K lemma L lemma (dorsal view) M palea with rachilla extension N palea (dorsal view) with rachilla extension O stigmas P lodicules Q stamens R caryopsis S fruit. Photos by Tran Van Tien from type locality.