Billolivia poilanei D.J.Middleton & H.J.Atkins, sp. nov.

Most similar to Billolivia minutiflora and B. vietnamensis but differs in the calyx lobes> 4 mm wide (<2 mm wide in B. minutiflora and B. vietnamensis).

Type:— VIETNAM. Haut Donai [Lam Dong], Djiring [Di Linh], Laouan [Lahouan], 1200 m, 6 June 1933, Poilane 22604 (holo P; iso P).

Small caulescent herb; stems with long brown hairs to 3 mm long. Leaves alternate, crowded near stem apex; petioles 1.3−4.2 cm long, densely covered in long brown spreading hairs to 5 mm long; lamina elliptic, 6.3−14.5 × 2.8−5.2 cm, 2.3−3.4 times as long as wide, base cuneate to rounded, apex short acuminate, margin so minutely crenate as to appear entire, secondary venation 8−12 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 both short and long hairs to 3 mm throughout, mostly longer on midrib and venation. Infructescence sessile; fruiting pedicels to 35 mm long, densely long pubescent. Calyx lobes in fruit imbricate, ovate, 7–9 × 4.8–5.8 mm, apex short acuminate to acute, densely pubescent in midline, more sparsely so towards margins. Fruit ellipsoid, 6–9 mm long, 4–5 mm wide, puberulent at apex. Seeds ellipsoid, 0.5 × 0.3 mm.

Etymology: — After Eugène Poilane (1887–1964), the collector of the type specimen and prolific collector in Vietnam.

Distribution: — Vietnam, Lam Dong Province.

Ecology: — On steep slope on clay soil in submontane tropical evergreen closed forest at 1200 m altitude.

Proposed IUCN conservation status: — Data Deficient (DD) (IUCN 2001, 2012). This species has not been collected since 1933 and its current distribution is entirely unknown.

This species is only known from the fruiting type collection. Although no flowers have been seen we can be confident that it is an undescribed species of Billolivia due to the alternate leaves and indehiscent fruit. It has calyx lobes divided to the base like in Billolivia minutiflora and B. vietnamensis but differs from both of those species in having the calyx lobes broadly ovate and very much wider. Fruiting calyces are known in both Billolivia minutiflora and B. vietnamensis and there is no evidence that the calyx shape in B. poilanei is due to differences in developmental stage.