Billolivia tichii Lưu, Q.D.Nguy

Long, Vũ Ng ọc, Nhân, Ph ạm H ữu, Văn, Nguy ễn Th ế & Trư ờng, Lưu H ồng, 2015, Billolivia tichii (Gesneriaceae), a new species from Vietnam, Phytotaxa 219 (2), pp. 190-194 : 190-193

Billolivia tichii Lưu, Q.D.Nguy ễn & N.L.Vũ, sp. nov. ( Fig. 1 )

Allied to Billolivia longipetiolata in having generally long pubescent petioles, coarsely dentate leaf margins and similar flower shape but it differs in having obovate to elliptic leaves, ellipsoid calyx, purple lines on the corolla throat and the base of lobes and red dot in the middle of filaments.

Type:— VIETNAM. Lâm Đ ồng Province: L ạc DƯƠng District, Đ ạ Chais Commune, Bidoup-Núi Bà National Park , W slope of Gia Rích mountain ridge, 18 November 2014, Lưu H ồng Trư ờng, Nguyễn Qu ốc Đạt, Ph ạm H ữu Nhân , Nguyễn Th ế Văn LUU, DAT, NHAN & VAN 1106 (holotype SGN!; isotypes SGN!, VNM!, DLU!, HNU!, HN!, VNMN!) .

Terrestrial herb; stems up to 1 m long, densely pubescent with brown multicellular uniseriate hairs to 5 mm long. Leaves alternate; petioles 4‒16 cm long, densely pubescent with brown multicellular uniseriate hairs to 5 mm long; lamina obovate to elliptic, slightly asymmetric, 11‒17 cm long, 5.5‒8.3 cm wide, base round to cuneate, apex acute, margin coarsely dentate, 12‒15 of secondary veins on each side of midrib, adaxial lamina dark green, glabrous, margin densely ciliate, abaxial lamina pale green or pale purple, with sparse appressed brown hairs to 1 mm long, on midrib and venation, sometimes also on lamina between veins. Inflorescences axillary, 2‒12-flowered; peduncle brownish pink, 0.5‒2.5 cm long, sparsely pubescent; bracts ovate, to 13 × 7 mm, apex acute, pubescent on outer surface, with margins ciliate; pedicels pinkish white, 1‒3 cm long, sparsely pubescent. Calyx brownish red, ellipsoid, 13‒16 mm long, 7‒8 mm wide at widest portion, composed of a flaring tube and 5 ± equal lobes, densely long brown pubescent outside, glabrous inside; tube 6−7 mm long, 6−7 mm wide at mouth; lobes triangular, 5−6 mm long, 3.5−4 mm wide at base, apex acute, with margins ciliate. Corolla 24‒27 mm long, composed of a narrow tube which slightly flares towards oblique mouth and a 2-lipped limb with lobes recurved; tube 20‒22 mm long, white, outside pubescent, inside glabrous; throat white, turning light yellow after anthesis, with shortly stalked to subsessile glands and purple lines on the base of lobes; upper lip 2-lobed, 11−12 mm long, lobes 9−10 × 8−10 mm, orbicular; lower lip 3-lobed, 12−13 mm long, lobes orbicular, lateral lobes 7−8 × 8−9 mm, lower lobe 10−11 × 8−9 mm; all lobes white (turning light yellow after anthesis) at base, violet to pink at apex, outside sparsely pubescent with multicellular uniseriate hairs, inside with shortly stalked glands. Stamens inserted at 16‒17 mm from corolla base; filaments slightly curved, 5‒7 mm long, white with a red dot in the middle, sparsely glandular puberulent. Disc bowl-shaped, 5-lobed at apex, 1.5 mm high. Ovary 3.5‒4 mm long, 2 mm in diameter, glabrous; style 15‒17 mm long, densely covered with glandular hairs; stigma lobes 1.8‒2.0 mm long. Fruits unknown.

Distribution, habitat and phenology: — Found on humid soils along streams in montane moist evergreen closed forest at 1800‒1900 m in elevation, Bidoup-Núi Bà National Park, Đà Lạt Plateau, Southern Annamites, Vietnam ( Fig. 2 ). Flowering is seen in October to November.

Etymology: — Named after Nguyễn Thiện Tịch, a botanical lecturer at the University of Science in Hồ Chí Minh City, who first discovered the species and informed the authors about it as a possible new species.

Proposed IUCN conservation status: — Data Deficient (DD) ( IUCN, 2001 & 2012). Given the species is only known from a single location of far less than 100 km 2 that is currently fragmented by intensive fish farming and is likely to experience future expansion, it should be considered for listing in the Critically Endangered category, CR B1a&b(iii). However, as the forest type where it has been discovered crosses into the neighbouring national parks PhƯớc Bình and ChƯ Yang Sin, Billolivia tichii possibly occurs there. To investigate if this species is distributed in these parks, additional surveys are needed. In addition, it will be necessary to evaluate and assess associated threats in order to make a sound conservation assessment.

Notes:— Billolivia tichii is most similar morphologically to B. longipetiolata . Both species share several common characteristics, such as long pubescent petioles, pubescent stem, adaxially glabrous and abaxially sparsely pubescent leaves, leaf margins coarsely dentate and general shape and size of flowers. The violet tips to the corolla lobes are more similar, however, to those of B. violacea . A summary of the main characters distinguishing B. tichii from these two species is given in Table 1.

In the Đà Lạt Plateau two or three morphologically similar species of Billolivia are often seen growing in mixed populations along water courses; this holds for the case of B. tichii and B. longipetiolata . Our observations of the two species in situ over the last three years noted that the new species flowered from October to November while B. longipetiolata flowered from January to March. These non-overlapping flowering periods likely serve as an effective barrier preventing hybridisation. In fact, all the observed individuals of these two sympatric species well represent the distinguishing characteristics shown in Table 1 and during our extensive surveys in this area we did not observe any specimens that appeared to represent an intermediate or hybrid form.

Figures

FIGURE 1. Billolivia tichii. A. Habit. B. Petioles. C. Abaxial lamina. D. Adaxial lamina. E. Inflorescence. F. Flowers, side view. G. Corolla lobes, dorsal view.H. Longisection of corolla. I. Stamen. J. Ovary and style. K. Stigma. L. Cross section of ovary. M. Longisection of ovary. Photos: Phạm Hữu Nhân, Nguyễn Quốc Đạt, Nguyễn Thiện Tịch and Đặng Minh Trí.

FIGURE 2. Type locality (dark circle) of Billolivia tichii. The non-shaded area represents the mainland of Vietnam.