Michaelmoelleria vietnamensis F. Wen, Z.B. Xin & T.V. Do, 2020

Wen, Fang, Xin, Zi-Bing, Fu, Long-Fei, Li, Shu, Su, Lan-Ying, Maciejewski, Stephen, Huang, Zhang-Jie, Do, Truong Van & Wei, Yi-Gang, 2020, Michaelmoelleria (Gesneriaceae), a new lithophilous dwelling genus and species with zigzag corolla tube from southern Vietnam, PhytoKeys 146, pp. 89-107 : 89

Michaelmoelleria vietnamensis F. Wen, Z.B. Xin & T.V. Do sp. nov. Figs 1 , 4

Type.

Vietnam. Binh Dinh province, Tay Son district, Tay Giang community, La stream. 13°55'59"N, 108°45'43"E, ca. 148 m, WYG180329-01 (holotype: VNMN!, isotypes IBK!).

Description.

Herbs perennial, rosette when young and stem obviously elongated after years of growth. Stem fleshy, cylindrical, 6-30 cm long, 4-6 mm in diameter, densely white pubescent when young, but glabrescent to glabrous when aging. Leaves alternate on elongated aerial stem, 12-20 cm or more, nearly clustered near the top of the stem and look opposite. Petiole 4-8.5 cm long, 3-3.5 mm in diameter, densely white pubescent. Leaf-blade slightly fleshly to thickly chartaceous, when dried flimsily chartaceous, ovate to elliptic, glabrous, green to dark green, usually with irregular silvery or argenteous spots on the adaxial surface, but silvery-brown to slight yellowish-brown in dry season, 4.5-7 × 2.5-4 cm, base marginally oblique, often slightly cordate, cordate to broadly cuneate, apex obtuse, margin entire, sinuate or with inconspicuously undulate teeth, adaxially and abaxially erectly puberulent; venation alternate along main vein, lateral veins 5-7 on each side of midrib. Cymes axillary near stem apex, fasciculate, 6-10 flowered per plant; peduncle slender, 8-15 cm long, 1-1.5 mm in diameter, brownish-green, densely erectly puberulent; bracts 2, ovate, both usually deflected to same side, 9.8-10.5 × 2.5-2.7 mm, adaxially sparsely puberulent, abaxially sparsely puberulent; 1-flowered and 2-flowered per cyme but one of both often abortive; pedicel 1.5-3 cm long, 1-1.2 mm in diameter, green to lime, sparsely extremely white puberulent. Calyx actinomorphic, 5-parted to the base, segments lanceolate to narrowly lanceolate, 8-8.5 mm long, 2-2.3 cm in diameter at the base, apex acute but top usually formed hammer-shape, margin entire, outside sparsely white puberulent, inside glabrous. Corolla obviously curving to zigzag funnelform, zygomorphic, 8-8.5 cm long, outside bluish-purple to purple, densely glandular and glandular-puberulent, inside purple, nearly glabrous, the color of the throat same as the corolla with two brownish-yellow stripes and sparse dark yellow glands on the surfaces of the two stripes. Corolla tube narrowly curving or zigzag infundibuliform-tubular, bent at about 90° angle in the middle of corolla tube, and gradually slightly swollen from the middle to the base of the tube, 3.5-3.9 mm in diameter at middle/corner and 4.8-5.4 mm at the base of tube; dramatically enlarged to be trumpet-shaped from the middle of corolla tube toward limb, 1.9-2.3 cm wide at the orifice of the corolla limb. Corolla limb 2-lipped, adaxial lip 2-lobed, lobes semi-rounded to slightly obliquely oblong-rounded, 1.3-1.5 × 1-1.2 cm; abaxial lip 1.5-1.9 cm long, 3-lobed, middle lobe rounded to oblate and narrowed at the base of middle lobe, 1-1.1 × 0.9-1 cm, lateral lobes orbicular to slightly obliquely oblong-rounded to oblate, 0.9-0.95 × 1.1-1.2 cm. Stamens 4, bigger pair adnate to corolla tube ca. 2.8 cm from the base and smaller pair adnate to corolla tube ca. 2.5 cm from the base, coherent; anthers glabrous; filaments glabrous to very sparsely glandular-puberulent, but near the top of filaments and the part close to anther densely glandular-puberulent, longer pair 8-9 mm long and shorter pair 7-7.5 mm; anthers glabrous, 2.2-2.5 mm long, margin of locule dark purple to purplish-brown; pollen gray; staminode 1, punctate, adnate to corolla tube 2-2.1 cm from base, ca. 1 mm long. Disc annular, ca. 1 mm high, margin entire. Pistil 8-8.5 cm long; ovary cylindric-linear, glabrous, 3.5-4 cm long, pale green; style linear, densely erect glandular and glandular-puberulent, ca. 4.5 cm long; stigmas 2-lobed, often gathering together but slightly opened at the end of flower, lobes ligulate, pink, sparsely glandular-puberulent at the base of stigma lobes but glabrous from the middle to the top of stigma lobes, 3.6-3.7 mm long. Capsule straight in relation to pedicel, linear, glabrous, 7.5-10 cm long, 2-2.5 mm in diameter, straight, dehiscing loculicidally to base, splitting along one suture, straight, not twisted.

Phenology.

Flowering occurs from March to April and fruiting from March to June.

Etymology.

The genus is named for the famous botanist, Dr. / Prof. Michael Möller, from the Royal Botanic Garden Edinburgh, and the species is named for Vietnam, which holds the first discovered and only known location for the species.

Figures

Figure 1. Photos of the new genus, Michaelmoelleria, the population in natural habitat. M. vietnamensis F. Wen, Z. B. Xin & T. V. Do A habitat along the La stream B habit C plants in flower D frontal view of flower in natural habitat E lateral view of flower in natural habitat. Photos by Fang Wen, arranged by Wen-Hua Xu.

Figure 4. Photos of new genus, Michaelmoelleria F. Wen, Y. G. Wei & T. V. Do. M. vietnamensis F. Wen, Z. B. Xin & T. V. Do A flowering potted plant in GCCC's greenhouse B frontal view of the corolla and the corolla tube C different angles of a lateral view of corolla and corolla tube (I) D different angles of lateral view of the corolla and the corolla tube (II) E cyme F bracts (above: adaxial surface; below: abaxial surface) G calyx lobes H lateral view of flower and bud I calyx lobes (the left three: adaxial calyx lobes surfaces; the right two: abaxial calyx lobes surfaces) J opened corolla showing stamens and staminode K our fertile anthers L pistil and calyx M stigma. Photos by Fang Wen, arranged by Wen-Hua Xu.