Impatiens bokorensis S.H.Cho & B.Y.Kim, 2017

Cho, Seong-Hyun, Kim, Bo-Yun, Park, Han-Sol, Phourin, Chhang & Kim, Young-Dong, 2017, Impatiens bokorensis (Balsaminaceae), a new species from Cambodia, PhytoKeys 77, pp. 33-39 : 34-36

Impatiens bokorensis S.H.Cho & B.Y.Kim sp. nov. Figures 1 , 2

Type.

CAMBODIA. Kampot Province, Phnum Bokor National Park , sandstone tables in evergreen forest margin, 10°38'20.8"N, 104°00'16.0"E, a.s.l. 1,050 m, 24 August 2015, with flowers, Cho S.H, Kim B.Y., Park H.S., Chhang Phourin CB-3112 (holotype HHU!, isotypes KB!, KRIB!, RUPP!) .

Diagnosis.

Impatiens bokorensis is most similar to the Thailand endemic species Impatiens patula Craib in habit but is readily distinguished from the latter by the orbicular-obovate dorsal petal, shorter pedicels and larger seeds (Table 1 ).

Description.

Herbs, annual, terrestrial, hermaphroditic. Stems erect, 15-40 cm tall, tinged purplish red, branched, glabrous or sparsely puberulous on the upper part. Leaves simple, alternate; petioles subsessile to 1.4 mm; leaf blade lanceolate to ovate-lanceolate, apex acuminate, base narrowly cuneate to attenuate, 2.5-7.0 × 0.6-2.0 cm, upper surface pubescent, lower surface glabrous to sparsely pubescent, secondary veins pinnate, 6 to 8 on each side of mid-vein, margin serrate, teeth mucronate and purple tinged, strigose-ciliate at base; strigose-ciliate, 4-14, 1-2.7 mm long, purple to purplish black, minutely puberulous at base. Flowers axillary, solitary, rarely 2 fascicled, zygomorphic, minutely puberulous; pedicels slender, erect, purplish red, 1.4-2.0 cm long, glabrous, bracteate at base; bracts linear, up to 4 mm; lateral sepals 2, linear-lanceolate, 2.5-3 mm long, glabrous; lower sepal funnel-form, pink, ca. 5 mm long, ca. 3 mm deep; spur 17-23 mm long, slightly curved; dorsal petal, orbicular-obovate, ca. 6 × 8 mm, horned at apex, horn 2.2-2.3 mm long; lateral united petals separate, bilobed, ca. 11 mm long; upper petals oblong, 6.0-6.5 × ca. 3.0 mm, minutely apiculate; lower petals, 9.0-9.3 × 3.5-3.8 mm; androecium ca. 2.8 × 1.6 mm; stamens 5, connate, surrounding gynoecium; filaments ca. 0.7 mm; ovary fusiform, pubescent, ca. 2.5 × 1.0 mm; style glabrous, ca. 0.2 mm long; stigma 5, ca. 0.25 mm long. Fruit a capsule, fusiform, ca. 15 × 6 mm, pubescent with scurfy hairs, 3[4]-seeded. Seeds obovoid, slightly compressed, 3.8-4.6 × 2.6-3.2 mm, pubescent with spirally sculptured hairs.

Specimen examined.

CAMBODIA. 16 November 2015, with fruits, Cho et al. CB-3432 (HHU!, KRIB!); 2 September 2016, with flowers, Kim et al. CB-3537 (HHU!)

Phenology.

Flowering specimens were collected in August and fruiting specimens in November.

Distribution and habitat.

Impatiens bokorensis grows on sandstone tables in evergreen forest margins at 1,050 m a.s.l.. Endemic to southwestern Cambodia, Impatiens bokorensis is at present known only in the type locality.

GenBank Accession No.

Cho et al. CB-3432: KX171761 (ITS).

Conservation status.

Impatiens bokorensis was collected in Phnum Bokor National Park in southwestern Cambodia. Until now, only one population, consisting of ca. 200 individuals, has been discovered in the park area; therefore, it is preliminarily classified as data deficient (DD) according to the IUCN Red List criteria (IUCN 2001).

Figures

Figure 1. Impatiens bokorensis A Flowering individual B Fruiting individual C-D Developing flower bud E Mature flower (before pollination) F-G Mature flower (after pollination) H Developing gynoecium I Petals J Androecium K Developing fruit L-M Seed N-O strigose-ciliate at leaf base: Cho et al. CB- 3112, 3432. Illustration by Hye-Woo Shin.

Figure 2. A-E Impatiens bokorensis A Habit B-C Flower D strigose-ciliate at leaf base E Capsule: Photos by Seong-Hyun Cho.