Billolivia vietnamensis D.J.Middleton & Luu, 2014

Billolivia vietnamensis D.J.Middleton & Luu View in CoL , sp. nov. ( Fig. 3 View FIGURE 3 , 7 View FIGURE 7 )

Most similar to Billolivia minutiflora but differs in the more densely pubescent abaxial surface of the leaves, the much longer hairs on the adaxial leaf surface, the smaller flowers, the pubescence of the inside of the corolla tube from the stamens to just above the base (only to just below stamens in B. minutiflora ) and the pubescence on the apex of the ovary (glabrous in B. minutiflora ).

Type:— VIETNAM. Binh Phuoc, Bu Gia Map National Park, Forest Protection Station no. 8 , 400 m alt., 19 December 2011, Luu Hong Truong & Nguyen Quoc Dat BGM1595–BGM1603 [a single gathering in sequential number series] (holotype SGN [BGM1602] ; isotypes SGN [BGM1595, BGM1596, BGM1597, BGM1598, BGM1600] , E [BGM1599, BGM1601, BGM1603] ).

Caulescent herb to 20 cm tall; stems with long brown hairs to 6 mm long. Leaves alternate, crowded near stem apex but with internodes up to 1 cm long; petioles 1.5−8 cm long, densely covered in a mixture of long brown spreading hairs to 6 mm long and shorter appressed brown hairs; lamina elliptic, 6.5−9.5 × 2.3−4 cm, 2.2−3.8 times as long as wide, base cuneate, apex short acuminate, margin so minutely dentate as to appear entire, secondary venation 5−10 veins on each side of midrib with weaker intersecondaries between, tertiary venation alternate percurrent, adaxial lamina with sparse long hairs throughout, margin ciliate, abaxial lamina with shorter hairs c. 0.5 mm long between the veins and both short and long hairs to 4 mm long on midrib and venation. Inflorescences sessile, c. 4-flowered; pedicels c. 12–15 mm long, densely long pubescent. Calyx of 5 lobes almost divided to base with connate part <1 mm long; lobes narrowly ovate, 6−9 × 0.8−1.3 mm, apex caudate, outside densely covered in long eglandular hairs to 3.5 mm long, inside glabrous. Corolla 18−25 mm long, composed of a narrow tube which slightly curves downwards in lower half and slightly flares towards mouth and a 2-lipped limb, white with purple lines along tube and onto lobes, ventral surface of throat and tube yellow; tube 11–18 mm long; upper lip 2-lobed, 3−4.5 mm long, sinus between lobes 2−3 mm, lobes 2−3 × 2−3 mm; lower lip 3-lobed, 5.5−7 mm long, lobes deltoid to orbicular, apices rounded, lateral lobes 4.2−5 × 2.2−4 mm, medial lobe 3.8−4.5 × 2.4−2.8 mm; corolla outside glabrous at base of tube, with short hairs on narrow part of tube above this and with short and long hairs on upper part of tube and outside of lobes, inside densely pubescent below stamens insertion, glabrous in bottom 3 mm, short glandular hairs on inside of lobes. Stamens inserted at c. 7.5 mm from corolla base; filaments c. 4.5 mm long, narrow at base, widening around middle and curved and twisting at this point, pubescent in upper half; anthers 1.6−2 × 1−1.5 mm; lateral staminodes 2−2.5 mm long, medial staminode c. 0.8 mm long. Disc an annular or lobed ring, 0.4−0.5 mm high. Ovary 4.5−5.5 mm long, few sessile glands over most of ovary but glandular and eglandular pubescent at top; style 6−7 mm long, pubescent throughout; stigma lobes 0.6−0.7 mm long. Fruit ellipsoid, 6.5−8.5 mm long, 3−4.5 mm circumference, pubescent distally.

Etymology: — After Vietnam, the country of origin.

Distribution: — Vietnam, Binh Phuoc Province.

Ecology: — On wet soils or rocky cliffs along streams in lowland evergreen closed forest at c. 400 m altitude.

Proposed IUCN conservation status: — Data Deficient (DD) ( IUCN 2001, 2012). This species is currently only known from Bu Gia Map National Park and has not been found in surrounding areas in Vietnam even though these have also been surveyed. However, Binh Phuoc Province has suffered considerable deforestation in the last 20 years or so, largely through conversion to agriculture. It is possible that it once had a wider distribution which is not reflected in herbarium specimens due to inadequate collecting in the area. The known distribution in the National Park is not currently under any threat. This species is the most geographically isolated in the genus as it is the only one which is not from Lam Dong province. As the forest complex in which it is found crosses the border into eastern Cambodia it is possible that Billolivia vietnamensis also occurs there. Consequently, as the true distribution and potential threats are not well known it must remain Data Deficient for the present.