Chayamaritia vietnamensis F.Wen, T.V.Do, Z.B.Xin & S.Maciej, 2021

Xin, Zi-Bing, Fu, Long-Fei, Maciejewski, Stephen, Huang, Zhang-Jie, Do, Truong Van & Wen, Fang, 2021, Chayamaritia vietnamensis (Gesneriaceae), a new species from Son La Province, northern Vietnam, PhytoKeys 177, pp. 43-53 : 43

Chayamaritia vietnamensis F.Wen, T.V.Do, Z.B.Xin & S.Maciej sp. nov. Figs 2 , 3C

Diagnosis.

The new species can be easily distinguished from the known Chayamaritia species by its peltate leaf blades. Besides, it differs from C. banksiae by its leaf blades apex rounded and margin entire (vs. apex shortly acuminate and margin minutely dentate); bracts 3, apex rounded and margin entire (vs. 2, apex acuminate and margin dentate); calyx lobes inside glabrous and margin entire (vs. inside with white appressed hairs in upper half, margin coarsely dentate); corolla lobes margin entire (vs. margin being minutely dentate); lateral staminodes 2.5-4 mm long (vs. 5.5-11 mm long). It also differs from C. smitinandii by its leaf blades apex rounded and margin entire (vs. apex acuminate and margin minutely dentate); bracts 3, ovate narrow and apex rounded (vs. 2, narrowly elliptic to lanceolate, somewhat falcate, apex acuminate); calyx lobes inside glabrous and margin entire (vs. inside densely pubescent, margin slightly toothed or appearing as large sessile glands on margin).

Type.

Vietnam. Son La Province: Moc Chau District, Xuan Nha Nature Reserve , 20°43'N, 104°40'E, elev. ca. 850 m, 31 October 2019, F. Wen, T.V. Do, Z.B. Xin & S. Maciejewski, VMN-CN1214 (Holotype: VNMN!; Isotypes: IBK!, VNMN!) .

Description.

Herbs perennial, rhizomatous prostrate thickened stem. Leaves basal, alternately arranged, numerous; petioles cylindrical, 10-25 cm long, 6-8 mm in diameter, densely covered with short white appressed hairs; leaf blade ovate to elliptic, peltate, 12-20 × 10-15 cm, 1.2-1.3 times as long as wide, both surfaces densely covered with short white appressed hairs, base rounded, apex rounded, margin entire; lateral veins 6-9 on each side of the mid-rib, impressed on the adaxial surface, prominent on the abaxial surface. Inflorescences cymose, all axes and bracts pale green with red appressed hairs; cymes 4-6, axillary, 1-3-branched, 2-12-flowered; peduncle 15-25 cm long, 4-6 mm in diameter, scattered villous; bracts 3, narrow ovate, 1.3-1.6 cm long, 5-6 mm wide, adaxially sparsely villous, abaxially densely villous, margin entire, apex rounded; pedicel 2.5-3.5 cm long, 1.5-2 mm in diameter, spreading puberulent. Calyx 5-parted nearly to the base, strongly imbricate; lobes ovate, ca. 1.3 cm long, ca. 6 mm wide, appressed villous outside, glabrous inside, margin entire, apex acuminate. Corolla 5.5-6.5 cm long, dark purple throughout outside, white to pale purple with two parallel yellow lines ventrally inside, lobes purple outside and inside, paler at base; tube 3.5-4 cm long, 1-1.2 cm in diameter at the mouth, 6-8 mm in diameter at the base; limb distinctly 2-lipped, adaxial lip 2-parted to over middle, lobes ca. 1 × 1 cm, orbicular; abaxial lip 3-parted to near the middle, lobes 1.3-1.5 × ca. 1 cm, oblong. Stamens 2, adnate to ca. 2.2 cm above the base of the corolla tube; filaments 1-1.2 cm long, white, sparsely pubescent, strongly geniculate at ca. 5 mm above the filament base, anthers ca. 2 mm long, sparsely pubescent. Staminodes 3, lateral ones 2.5-4 mm long, white, glabrous, adnate to 1.8 cm above the base of the corolla tube, the middle one ca. 0.5-1 mm long, adnate to 1.2 cm above the base of the corolla tube. Disc orbicular, ca. 3 mm in height, 5-crenate at the margin, glabrous. Pistil 4-4.5 cm long, ovary 2.5-2.8 cm long, 2-2.5 mm in diameter, mixed pubescent and glandular-pubescent; style 1-1.2 mm long, ca. 0.6 mm in diameter, mixed pubescent and glandular-pubescent; stigma only of lower lobe, bifid with blunt lobes, lobe ca. 3 mm long, ca. 0.5 mm in diameter. Capsules straight, 5.5-6.5 cm long, ca. 3.5-4 mm in diameter.

Phenology.

Flowering occurs from October to December and fruiting from November to January.

Etymology.

The specific epithet " Chayamaritia vietnamensis " is derived from Vietnam, which holds the first discovered and only known location for the species.

Distribution and habitat.

Chayamaritia vietnamensis is hitherto only known from the type locality, Xuan Nha Nature Reserve, Moc Chau District, Son La Province, northern Vietnam. It grows on rock surfaces surrounded by limestone areas in a subtropical evergreen seasonal rain forest.

Conservation status.

Chayamaritia vietnamensis is known from two small-sized populations in the Xuan Nha Nature Reserve’s buffer zone. The EOO and AOO of the new species are about 6.15 km2 and 2.2 km2, respectively. Furthermore, the natural habitat is mostly disturbed by local farmers who impose intense pressure on the remaining primary forest patches, by converting the natural habitat of the species into cornfields. Thus, following the IUCN Red List Categories and Criteria ( IUCN 2019), it is provisionally assessed as endangered (EN B1ab(iii), B2ab(iii))

Figures

Figure 2. Chayamaritia vietnamensis F. Wen, T. V. Do, Z. B. Xin & S. Maciej A, B habitat C habit D adaxial (top) and abaxial (bottom) surface of leaf blade E cymes F peduncle G adaxial (top) and abaxial (bottom) surface of bracts H pistil, calyx and lateral view of corolla I opened corolla with stamens and staminodes J stamens with cohering anthers K pistil L adaxial (top) and abaxial (bottom) surface of calyx lobes. Photos by Fang Wen, arranged by Zi-Bing Xin.

Figure 3. Three species of Chayamaritia A C. banksiae D. J. Middleton B C. smitinandii (B. L. Burtt) D. J. Middleton C C. vietnamensis F. Wen, T. V. Do, Z. B. Xin & S. Maciej. Photos by Fang Wen, arranged by Zi-Bing Xin.