Lasianthus naikii V.S.Dang & Vuong, 2022

Dang, Minh Quan, Nguyen, Manh Ha, Hoang, Nghia Son, Le, Van Tho, Nguyen, Thi Mai Huong, Ho, Nguyen Quynh Chi, Truong, Ba Vuong & Dang, Van Son, 2022, Two new species of Lasianthus Jack (Rubiaceae) from southern Vietnam, European Journal of Taxonomy 806, pp. 19-31 : 20-25

publication ID	https://doi.org/ 10.5852/ejt.2022.806.1697
DOI	https://doi.org/10.5281/zenodo.6379958
persistent identifier	https://treatment.plazi.org/id/0387F954-292B-FF8A-FDD7-13DBFE83CA2F
treatment provided by	Felipe
scientific name	Lasianthus naikii V.S.Dang & Vuong
status	sp. nov.

Treatment

Lasianthus naikii V.S.Dang & Vuong sp. nov.

urn:lsid:ipni.org:names:77295607-1

Figs 1–2 View Fig View Fig ; Table 1 View Table 1

Diagnosis

Lasianthus naikii sp. nov. is similar to L. formosensis Matsumura ( Fig. 3 View Fig ) in leaf morphology and blue fruits, but differs from the latter by having secondary veins 5–6 pairs (vs 6–7 pairs), bracts present 0.5–1 mm long (vs absent), calyx tube 2–5 mm long (vs ca 1 mm long), calyx lobes 1–1.5 mm long (vs 3–4 mm long) and corolla lobes 6 (vs 5). For a further comparison see Table 1 View Table 1 .

Etymology

The new species is named in honor of Associate Professor Dr Akyo Naiki of University of the Ryukyus, Japan, for his contributions to the study of Rubiaceae in Vietnam.

Vernacular name

Xú hƯƠng ʻNaikiʼ.

Type material

VIETNAM • Gia Lai Province, K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve , primary evergreen forests; 14°29′10.00″ N, 108°32′19.12″ E; at 1000–1100 m a.s.l.; 22 Apr. 2021; Van- Son Dang, Ba Vuong Truong, Minh Quan Dang & Nghia Son Hoang Dang 453; holotype: VNM!; GoogleMaps isotypes: HN!, VNM GoogleMaps !.

Description

Shrubs, evergreen, 1–2 m tall; branches and branchlets terete, 1.5–3 mm diam., densely villous, internodes 2–3 cm long. Leaves opposite, blades oblong or elliptic-ovate, 12–14 × 3–5 cm, coriaceous, yellowish brown when dry, adaxially glabrous, abaxially villous especially on the midrib and secondary veins, apex acuminate or cuspidate, aristate 2–4 mm long, villous, base acute or obtuse, margin entire; midrib slightly prominent adaxially, prominent abaxially; secondary veins 5–6 pairs, ascending at an angle of 40–60° from midrib, curved to the margin, flat adaxially, distinct abaxially; tertiary veins reticulate; petioles 5–7 mm long, densely villous. Stipules triangular, 1.5–2 mm long, persistent, villous. Inflorescences cymose, sessile, 1–3-flowered; bracts small, 0.5–1 mm long, villous. Flowers sessile; calyx campanulate, 3–4 mm long, yellowish brown, densely villous outside, calyx tube 2–2.5 mm long, calyx lobes 6, linear-triangular, 1–1.5 mm long, tips acute; corolla cylindrical, 6–8 mm long, white, corolla tube 4–5 mm long, pubescent outside, corolla lobes 6, triangular, 2–3 mm long, puberulous outside, floccose inside; stamens 6, filaments short, anthers oblong, 0.6–1 mm long; ovary with 5 locules, style linear, 4–5 mm long, stigma 0.6–0.8 mm long. Fruit drupaceous, ovoid-globose, 7–9 mm long, 6–7 mm in diam., strigose, crowned by calyx lobes, blue when ripe; pyrenes 5. Seeds ovoid, 2–3 mm long, smooth to subwarty on the abaxial face, brown when dry.

Distribution, habitat and phenology

Lasianthus naikii sp. nov. is only known from its type locality at 1000–1100 m elevation. It grows under the shade of primary evergreen forest on clay, which is dominated by Garcinia cowa Roxb. ( Clusiaceae Lindl. ), Oroxylum indicum (L.) Kurz ( Bignoniaceae Juss. ), Tabernaemontana peduncularis Wall. ( Apocynaceae Juss. ), Dialium cochinchinense Pierre ( Fabaceae Lindl. ), Elaeocarpus kontumensis Gagnep. ( Elaeocarpaceae Juss. ), Litsea elongata (Nees) Hook. f. ( Lauraceae Juss. ), Lasianthus fordii Hance ( Rubiaceae Juss. ), Magnolia praecalva (Dandy) Figlar & Noot. ( Magnoliaceae Juss. ), Symplocos cochinchinensis (Lour.) S.Moore ( Symplocaceae Desf. ) and Syzygium chanlos (Gagnep.) Merr. & L.M.Perry ( Myrtaceae Juss. ). Flowering and fruiting specimens were collected in April.

Population and threats

The new species is so far only known from Kon Chu Rang Nature Reserve, Gia Lai Province, southern Vietnam. It was collected in a single population containing less than 50 individuals, occupying an area of less than 15 km 2.