Introduction
In recent years, many new species and one new genus of Gesneriaceae have been described from Vietnam (e.g. Middleton et al., Reference Middleton, Atkins, Luu, Nishii and Möller2014a,Reference Middleton, Leong-Škorničková and Nguyễnb; Middleton, Reference Middleton2015; Nguyen et al., Reference Nguyen, Dinh, Nguyen, Vu and Luu2016; Wen et al., Reference Wen, Do, Hong, Maciejewski and Wei2016; Chen et al., Reference Chen, Middleton, Nguyen, Nguyen, Averyanov, Chen, Nguyen, Möller and Shui2017, Reference Chen, Nguyen, Chen, Nguyen, Nguyen, Nguyen, Möller, Middleton and Shui2018a,Reference Chen, Zhang, Li, Nguyen, Nguyen and Shuib; Hong et al., Reference Hong, Li, Maciejewski, Wen and Do2018; Yang et al., Reference Yang, Chen, Wen and Kang2018). These have come about both through new exploration and through study of existing collections. Here two new species of Paraboea (C.B.Clarke) Ridl. from northern and central Vietnam are described from material in the Royal Botanic Garden Edinburgh.
Paraboea is one of the larger genera in the Gesneriaceae, with an estimated 130 species (Triboun & Middleton, Reference Triboun and Middleton2015; Puglisi & Phutthai, Reference Puglisi and Phutthai2017). The genus was revised by Xu et al. (Reference Xu, Burtt, Skog and Middleton2008) but much expanded later through the inclusion of Phylloboea Benth. and Trisepalum C.B.Clarke, and the description of many new species (Chen et al., Reference Chen, Möller, Shui and Zhang2008; Kiew, Reference Kiew2010; Middleton et al., Reference Middleton, Puglisi, Triboun and Möller2010; Puglisi et al., Reference Puglisi, Middleton, Triboun and Möller2011; Chen et al., Reference Chen, Möller, Zhang and Shui2012; Kiew, Reference Kiew2012; Triboun & Middleton, Reference Triboun and Middleton2012; Triboun, Reference Triboun2013; Wen et al., Reference Wen, Hong, Chen, Zhou and Wei2013; Puglisi et al., Reference Puglisi, Suddee, Triboun and Middleton2015; Triboun & Middleton, Reference Triboun and Middleton2015; Puglisi & Phutthai, Reference Puglisi and Phutthai2017). There are an estimated 70 species in Thailand, yet fewer than 20 species have been recorded from Vietnam, with no clear biogeographical or habitat reasons for such a marked difference in diversity. Many of the species known from Thailand and China are locally endemic, and it is highly likely that several more species from Vietnam will be discovered and described with increased collecting across the country, particularly in the limestone areas in the north.
Images of the specimens are available via the online Herbarium Catalogue of the Royal Botanic Garden Edinburgh and Tropicos, the botanical information system at the Missouri Botanical Garden:
http://data.rbge.org.uk/search/herbarium/?specimen_num=674785&cfg=zoom.cfg&filename=E00658392.zip
http://data.rbge.org.uk/search/herbarium/?specimen_num=674648&cfg=zoom.cfg&filename=E00658355.zip
Paraboea stellata D.J.Middleton, sp. nov.
Differs from all other Paraboea species in the combination of (sub)orbicular leaves with entire margin, branched hairs and straight fruit. – Type: Vietnam, Quang Binh, Bo Trach Distr., Tan Trach Municipality, about 1.5 km SE of A Rem village, 750–900 m, 25 i 2005, L.V. Averyanov, P.K. Loc, P.V. The, A. Averyanova, N.T. Vinh, N.Q. Vinh & N.T. Binh HAL6145 (holo E [E00658392]; iso HN n.v., MO [MO3035004]).
Rosulate lithophytic herb. Leaves: petiole 3.7–11.4 cm long, densely hirsute throughout with both simple and branched hairs; blade thickly coriaceous, (sub)orbicular, 3.3–7 × 2.8–5.6 cm, 1.1–1.5 times as long as wide, base rounded to cordate, apex rounded, margin entire, 4–6 secondary veins on each side of midrib, slightly impressed above, prominent beneath, tertiary venation mostly obscure, sometimes scalariform, very densely hirsute with both simple and branched hairs beneath, glabrous above. Inflorescence scapose, dichasial, 10–24.7 cm long; peduncle 8–20.7 cm long, densely hirsute at base, becoming glabrescent upwards but hirsute at nodes along with hairy aborted flowers; bracts spathulate, c.6 × 1.7 mm, densely hirsute outside, glabrous at base inside, densely hirsute in upper half; pedicels 8–11.5 mm, glabrous. Sepals oblong, apex rounded, 4.2 × 0.9 mm, glabrous. Corolla light blue, campanulate, c.12.5 mm long, glabrous inside and outside, upper lip 2-lobed, lower lip 3-lobed, all lobes orbicular, apices rounded; tube c.6 mm; upper lobes c.2 × 2.5 mm, lateral lobes c.4 × 4 mm, lower lobe c.5 × 5.2 mm. Stamens inserted in tube c.1.5 mm from base; filaments c.4 mm long, with few short-stalked glands; anthers adnate face to face, c.2 × 4.4 mm, few short-stalked glands dorsally; lateral staminodes c.0.7 mm, medial staminode c.0.3 mm. Disc absent. Ovary glabrous, c.4 mm long, c.1 mm wide; style c.3.8 mm long, with short-stalked glands; stigma capitate. Fruit a capsule, straight, >1.4 cm long (only one damaged fruit seen). Seeds c.0.5 × 0.2 mm.
Distribution
Known only from two localities in Quang Binh province in Vietnam.
Ecology
Reported from primary, selectively logged, closed, evergreen, broadleaved forest and from closed, coniferous forest. In both cases, it is reported from steep and rocky slopes and ridges, is reported not to be uncommon, and grows on wet and rich humus and in shaded cracks in rock. The rock is reported to be solid, marble-like, highly eroded, stratified, crystalline limestone at 663–900 m a.s.l.
Provisional IUCN conservation assessment
Endangered ENB2ab(iii). The area of occupancy is calculated at only 8 km2, but it is known from two localities that are not so far apart and could not, therefore, be described as fragmented. Although one of the localities is in a protected area, the other is not and with reports of selective logging.
Additional specimen studied. Vietnam. Quang Binh: Minh Hoa Distr., Hoa Son Municipality, B'Lam Lang limestone mt., around point 17°42′11.9″N, 105°47′37.4″E, 15 viii 2011, N.T. Hiep, N.Q. Hieu, N.V. Tap, N.S. Khang, N.Q. Vinh & L.T. Kien CPC4289 (E [E00547445]).
This new species is extremely distinctive due to the dense covering of multibranched hairs. Branched hairs are already known in Paraboea in P. vulpina Ridl. and P. tarutaoensis Z.R.Xu & B.L.Burtt from southern Thailand and Peninsular Malaysia. Both these species also have straight fruits as in Paraboea stellata but P. tarutaoensis is caulescent and has a dentate leaf margin and a white corolla, and P. vulpina has a crenate leaf margin, the leaves are pubescent above and the corolla tube is much shorter (2–2.5 mm).
Paraboea minutiflora D.J. Middleton, sp. nov.
Most similar to species in the Paraboea martinii (H.Lév. & Vaniot) B.L.Burtt group (see Xu et al., Reference Xu, Burtt, Skog and Middleton2008) in the large, branched inflorescence with reduced leaves at the base and long internodes, but distinct in the combination of non-winged petioles, cordate leaf blade base, corolla < 1 cm long and straight fruit. With the small campanulate corolla, it is most similar to Paraboea thorelii (Pellegr.) B.L.Burtt but differs in the lack of glandular hairs on the inflorescence axes, in the leaf base shape and in the straight fruit (twisted in Paraboea thorelii). – Type: Vietnam, Ha Giang, Phong Quang Municipality, Man Village, 595–787 m, 22°53′21″N–22°53′35″N, 104°56′45″E–104°56′35″E, 15 ii 2001, D.K. Harder, P.K. Loc, L.V. Averyanov, G.E. Schatz & S. Bodine 6322 (holo E [E00658355]; iso HN n.v., MO [MO3035005]).
Rosulate herb with woody rootstock. Leaves: petiole 5.5–13.6 cm long, densely covered with a brown matted indumentum, not winged; blade ovate, 9.4–15.4 × 5.7–12.2 cm, base cordate, apex rounded and apiculate or abruptly acuminate, margin entire to minutely crenulate, 7–9 secondary veins on each side of midrib, densely covered with a brown matted indumentum throughout beneath, more sparsely so above. Inflorescence scapose, possibly arising terminally (but rather obscured on the specimens), 29.8–31 cm long, with distantly spaced branches; peduncle 15.5–19 cm long, with a dense matted indumentum in lower parts, glabrescent distally, then red-purple shiny; bracts green, lower pair c.14 mm long, upper pairs progressively smaller; pedicels 2–4 mm long, glabrous. Calyx green, lobes oblong, 3–3.5 × 0.8–1.1 mm, apex rounded, glabrous. Corolla white and red-pink, campanulate, 6–7 mm long (slightly immature), with short-stalked glands outside, upper lip 2-lobed, lower lip 3-lobed, all lobes orbicular, apices rounded; tube c.4 mm long; upper lobes c.1.8 × 1.8 mm, lateral lobes c.1.5 × 2 mm, lower lobe c.1.5 × 2.5 mm. Stamens inserted in tube at c.0.8 mm from base; filaments c.2 mm long, with few short-stalked glands; anthers adnate face to face, c.1.7 × 3.3 mm, glabrous; lateral staminodes c.0.8 mm, medial staminode c.0.2 mm. Disc absent. Ovary (slightly immature) c.2 mm long, c.1 mm wide, glabrous; style c.1 mm long, glabrous; stigma capitate. Fruit a capsule, straight, 2.1–2.8 cm long (old dehisced fruit).
Distribution
Vietnam, Ha Giang Province. Known only from the type collection.
Ecology
Among limestone peaks and ridges in secondary forest and adjacent grassland, frequent on rocks and in pockets of soil on rocks.
Provisional IUCN conservation assessment
Data Deficient (DD). This species is known only from the type collection from 2001, although it is reported in secondary forest, which suggests some tolerance of disturbance.
There are only slightly immature corollas on the specimens available for study, and it is unclear to what extent the corolla and fertile parts might further expand with maturity, so the dimensions in the description should be viewed in this light. The flowers are sufficiently mature to see that they will be small even when fully mature, and the diagnostic characters to assess that it is indeed new do not rely on comparing corolla dimensions.
The species in the Paraboea martinii group, to which P. minutiflora is compared above, have twisted fruits, whereas P. minutiflora has straight fruit (see the MO isotype). Paraboea minutiflora is not similar to any straight-fruited species. Xu et al. (Reference Xu, Burtt, Skog and Middleton2008) noted instances of otherwise similar species differing in twisted and non-twisted fruits, and Puglisi et al. (Reference Puglisi, Middleton, Triboun and Möller2011) found that species with straight and twisted fruits were scattered through the phylogeny.
