Machilus brevipaniculata Yahara & Tagane, 2016

Yahara, Tetsukazu, Tagane, Shuichiro, Mase, Keiko, Chhang, Phourin & Toyama, Hironori, 2016, Flora of Bokor National Park V: Two new species of Machilus (Lauraceae), M. bokorensis and M. brevipaniculata, PhytoKeys 65, pp. 35-46 : 38-40

Machilus brevipaniculata Yahara & Tagane sp. nov. Figs 3 , 4

Diagnosis.

Similar to Machilus kingii Hook.f. in leaf shape and size, and short panicles less than 5.5 cm long, but distinct from Machilus kingii by its naked bud (vs. bud covered with scales in Machilus kingii ), lamina foveolate on both surfaces (vs. obscure on lower surface), fewer flowers per panicle (3-5 vs. 4-9), and smaller perianth lobes (2 mm vs. 3-3.5 mm long).

Type.

CAMBODIA. Kampot Province, semi-evergreen secondary forest at the bottom of Mt. Bokor , 10°35'35.6"N, 103°58'43.1"E, alt. 65 m, 7 Dec. 2013, Tagane S., Toyama H., Fuse K., Iwanaga F., Rueangruea S., Suddee S., Kanemitsu H., Zhang M., Kim W., Loth M. 6011 (holotype KYO!, isotypes BKF!, FU!, PNP!) .

Description.

Small tree, 8 m tall. Branchlets sericeous near the tip, soon glabrous, brownish when dry, old branches greyish brown to reddish brown, without lenticels; terminal buds naked. Leaves alternate; blades lanceolate to oblanceolate, 5.0-8.3 × 1.4-3.1 cm, leathery, reddish brown when dried, glabrous and foveolate on both sides, lustrous adaxially when dry, base cuneate, margin slightly revolute when dry, apex acute to obtuse, midrib concave adaxially, elevated abaxially, lateral veins 8-10 pairs; petioles 0.5-1.4 cm, glabrous. Inflorescences paniculate, terminal or arising as lateral branches of newly sprouted shoots, 4-11 cm long, usually with frondose bracts subtending secondary paniculate axes, secondary axes 0.8-1.3 cm long with 3-15 flowers. Pedicels ca. 2 mm long. Flowers yellowish green. Outer perianth lobes ovate, ca. 2 × 1 mm, inner ones broadly ovate, ca. 2 × 1.3 mm, pubescent on both surfaces, with many gland dots. Stamens 9, subequal, ca. 1.5 mm long, hairy at base, anthers 4-celled, ca. 1 mm long; glands of 3rd series stipitate, ca. 0.3 mm diam. Staminodes 3, ca. 0.6-1 mm long, glabrous. Ovary ellipsoidal, ca. 0.8 mm in diam., glabrous. Style ca. 0.8 mm long, glabrous. Fruits not seen.

Distribution.

Cambodia. Known only from the lowland of Bokor National Park.

Habitat and ecology.

This species was found in evergreen forest at the foot of Mt. Bokor. Flowering specimens were collected in December.

GenBank accession No.

Tagane et al. 6011: AB987676 (rbcL), AB987675 (matK), AB987674 (ITS).

Preliminary conservation assessment.

Critically endangered (CR) ( IUCN 2012). We collected only one flowering individual of this species at alt. 65 m during 7 field surveys on the southern slope and top plateau of Mt. Bokor ( Tagane et al. 2015). Further botanical inventories might enable us to find more individuals, but it seems to be a rare species. Considering the fact that the forest is almost cleared in the foot of Mt. Bokor (below 100 m in particular), we believe that this species should be considered critically endangered.

Note.

This species is distinct in having naked terminal buds and panicles having frondose bracts subtending secondary paniculate axes, while most of Machilus species have scaly terminal buds and panicles without frondose bracts. According to our unpublished ITS tree, this species is sister to Machilus coriacea A.Chev. endemic to southern Vietnam, but can be readily distinguished from the latter by the two above mentioned traits and also in having glabrous leaves (vs. densely hairy beneath when young in Machilus coriacea ).

Figures

Figure 3. Machilus brevipaniculata Yahara & Tagane. a flowering branch b flowers c abaxial lower surface of lamina d flower e holotype: Tagane et al. 6011 (KYO), scale bar = 10 cm, f portion of leaves g apical bud. Photographs: a, b, d by S. Tagane and c by S. Rueangruea.

Figure 4. Machilus brevipaniculata Yahara & Tagane, a flowering branch b top of branch with abaxial leaf surface c flower buds d flower e outer perianth lobe f inner perianth lobe g - i stamens in 1 st, 2 nd and 3 rd whorl from left j staminode k pistil. Materials from Tagane et al. 6011 (KYO). Drawn by K. Mase.