Monolophus odontochilus Y.H.Tan & H.B.Ding, 2020

Ding, Hong-Bo, Yang, Bin, Maw, Mya Bhone, Win, Pyae Pyae & Tan, Yun-Hong, 2020, A new species and two new combinations of Monolophus (Zingiberaceae) from Indo-Burma, PhytoKeys 138, pp. 155-162 : 155

Monolophus odontochilus Y.H.Tan & H.B.Ding sp. nov. Figure 1

Diagnosis.

Monolophus odontochilus is morphologically similar to M. linearis (Wall.) Wall. from India in having white flowers with yellow blotch at the base of the labellum, but differs by having elliptic to oblong leaves (vs. linear-lanceolate to lanceolate leaves), bilobed ligules (vs. entire ligules), semi-orbicular crenate labellum (vs. trilobed labellum) and purely white corolla (vs. pinkish white corolla).

Type.

Myanmar. Kachin State: Putao District, Gathu Village. 27°29'07.23"N, 97°58'19.49"E, 643 m, 01 June 2018, Y.H.Tan, B.Yang, H.B.Ding, X.D.Zeng, M.B.Maw and H.L.Neing M3886 (holotype: HITBC!, isotypes: RAF!).

Description.

Perennial herbs, rhizome short; pseudostem erect, leafy 50-70 cm long. Leaves 5-13, sub-sessile, elliptic to oblong, 10.2-14 × 3.0-5.0 cm, base cuneate, apex caudate to 2.0 cm long, margins entire, adaxial surface dark green, glabrous, abaxially light green, pubescent; ligule membranous, 6-8 mm long, hairy, apex unequally bilobed. Inflorescences terminal, 5-7 cm long, rachis glabrous; flowers white with yellow blotch at the base of the labellum; bracts 4-6, along rachis, distichous, oblong, 3.5-4.0 × 1.0-1.3 cm, greenish, outer surface pubescent, base truncate, apex cuspidate to 0.8 cm, 2-flowered; bracteoles membranous, lanceolate, ca. 1.5 × 0.8 cm, pubescent, rounded; calyx tubular, 1.3-1.4 × 0.3-0.4 cm, pubescent, greenish, split 6-7 mm down one side, apex acute; floral tube 4.3-4.5 cm, ca. 3.5 mm wide at mouth, white, glabrous; dorsal corolla lobe lanceolate, 2.2-2.3 × 0.6-0.7 cm, white, glabrous, hooded at apex, apical cusp ca. 2 mm long; lateral corolla lobes similar to dorsal lobe, narrower, 2.0-2.1 × 0.3-0.4 cm, hooded at apex, apical cusp ca. 1 mm long; lateral staminodes elliptic, 1.5-1.6 × 0.9-1.0 cm, white, apex rounded; labellum semi-orbicular, 4.4-4.8 × 3.2-3.6 cm, white with yellow spot at base, margin crenate; anther 4-5 mm long; anther crest flabellate, 2-3 × 4-5 mm, white, apex entire; stigma funnel-shaped, inserted between anther sac, margin raised on both ends, ciliate; ovary oblong, 3-4 mm long, pubescent, 3-locular.

Phenology.

Flowering in May to June. Fruit not seen.

Etymology.

The species epithet ' odontochilus ' refers to the crenate labellum.

Distribution and habitat.

Monolophus odontochilus is endemic to Kachin State, Northern Myanmar, only known from its type locality, Gathu Village, Putao District. It grows in humid environments or along streams of tropical rain forest at an elevation of 550-750 m.

Conservation status.

This new species appears to be restricted to a very moist habitat in Gathu Village, Putao District, Kachin State, Northern Myanmar. According to our observations in the field, the two known populations are composed of about 50 mature individuals in each. Overall, however, the species has been deemed to be Data Deficient (DD) following IUCN Red list Categories and Criteria ( IUCN 2017). Further field surveys in northern Myanmar are needed to gain more information on its distribution.

Affinities.

Monolophus odontochilus is morphologically similar to M. linearis (Wall.) Wall. ( Wallich 1820, 1832) in having white flowers with a yellow blotch at the base of the labellum. After comparison with specimens and descriptions in literature ( Chaturvedi et al. 2012; Roy and Barbhuiya 2013), it was found that M. odontochilus can be distinguished from M. linearis , even on the basis of its vegetative characters: e.g. Monolophus odontochilus has unequally bilobed ligule (vs. entire ligule, respectively), longer calyx (1.3-1.4 cm vs. 0.8-0.9 cm, respectively), bigger lateral staminodes (1.5-1.6 × 0.9-1.0 cm vs. ca. 1.0 × 0.7 cm, respectively). Monolophus odontochilus , furthermore, differs in having elliptic to oblong leaves (10.2-14 × 3-5 cm), margin crenate labellum (non-trilobed) and purely white corolla. Monolophu linearis has linear lanceolate leaves (1.5-6.5 × 0.5-1 cm), trilobed labellum and pinkish white corolla. A diagnostic key to the new species of Monolophus and its closely related species is provided.

Figures

Figure 1. Monolophus odontochilus Y. H. Tan & H. B. Ding, sp. nov. A habitat B ligule C leaf blade abaxially D habit E single leaf (adaxially and abaxially) F flower (side view) G flower (front view) H anther with stigma and crest (front and back view) I stigma J dorsal corolla lobe K lateral corolla lobes L bracts M bracteoles and young flower N calyx O ovary P labellum and floral tube Q lateral staminodes R stamen and stigma S ovary with style. Photographed by H. B. Ding