Hedyotis dinganensis Q. L. Wang, L. X. Yuan & Z. N. Wang, 2019

Wang, Qinglong, Yuan, Langxing, Tang, Huan, Wang, Zhunian, Wang, Maoyuan & Yang, Qing, 2019, Hedyotis dinganensis, a new species of Rubiaceae from Hainan, China, Phytotaxa 399 (1), pp. 44-48 : 44-46

Hedyotis dinganensis Q. L. Wang, L. X. Yuan & Z. N. Wang , sp. nov. ( Figures 1 & 2 )

The species resembles H. yazhouensis Xing & Wang (2003: 87) and H. paridifolia Dunn (1912: 362) , but differs from the former by its stipule triangular to broadly triangular, ca. 10× 12 mm (not obtrapezoid to spatulate, ca. 6× 9 mm), calyx lobes 7–8× 1.5–2 mm (not ca. 35 × 1 mm), stigmas exserted (not included), and from latter by its stipule ca. 10× 12 mm (not 1–3.2 mm long), calyx lobes 7–8× 1.5–2 mm (not 1–1.2 mm).

Type: China. Hainan: Dingan Xian, Maan Shan , on mountain slopes under broad-leaved forest, ca. 179 m alt., 19°16’50” N, 110°20’14” E, 21 April 2018 (fl.), Wang Qinglong. 787641 (holotype IBSC; isotype [spirit] TCGRI) .

Perennial, erect, dwarf herbs, to 10 cm tall; stems weakly 4-angled. Leaves sessile or subsessile, crowded at tops of stems; blade leathery or thickness papery, obovate or ovate-elliptic, 8–15 × 4–10 cm, base obtuse, apex obtuse to broadly obtuse, margin entire, ciliate; veins distinct, deep above; secondary veins 4–9 pairs; stipules triangular to broadly triangular, ca. 10 mm long, ca. 12 mm wide, hispidulous to glabrescent, marginally entire to glandular-serrate, apex acuminate or with 8–10 narrowly triangular to linear lobes or bristles for 1–7 mm long. Inflorescence terminal or upper axillary, congested-cymose, capitate, or fasciculate, broadly hemispherical, 4–6 cm in diam., many-flowered, subsessile; bracts linear-lanceolate, ca. 7 mm long, apex acute. Flowers subsessile. Calyx sparsely puberulent or glabrous; hypanthium portion ellipsoid to obovoid, ca. 2 mm; lobes 4, linear, 7–8 × 1.5–2 mm. Corolla blue-purple, or white, slenderly funnelform, outside sparsely puberulent; corolla tube ca. 8 mm. Stamens 4; anthers oblong, ca. 1 mm long. Long-styled flowers: stigma exserted; anthers a little below the throat of corolla tubes. Shortstyled flowers: opposite the former. Fruit indehiscent, ellipsoid to obovoid, ca. 3 mm, pilosulous; seeds 8–12, black, papillose. Flowering from April to October; fruiting from September to December.

Distribution and ecology: — Hedyotis dinganensis is mainly distributed in the Maan Shan, Dingan Xian, northeastern Hainan, and Qiongzhong Xian, central Hainan, China. It grows on mountain slopes under broad-leaved forest, at altitudes of 100– 450 m.

Etymology: —The specific epithet is derived from the type locality, Dingan Xian.

Conservation status: —So far, two populations of H. dinganensis have been observed, each with less than 200 mature plants. And furthermore, they are situated on lower altitudes where its habitats are fragile, thus, following the IUCN (2012) red list categories and criteria, the conservation status of this species is assessed as ‘Critically Endangered’ (CR).

Similar species: — Hedyotis dinganensis is similar to H. yazhouensis and H. parviflora , but can be easily distinguished by the following characteristics ( Table 1).

Additional specimens examined (Paratypes): — China. Hainan: Qiongzhong Xian, Zhongping Zhen, in forests,

350 m alt., 2018-10-11, Yuan Langxing 787656 (TCGRI).

Figures

FIGURE 1. Hedyotis dinganensis sp. nov. A. Habit; B. Inflorescence; C. Leaf blade adaxially, abaxially; D. Stipule in face view; E. Portion of inflorescence; F. Flower bud; G. Calyx; H. Long-styled flower in face view; I. Short-styled flower in face view; J. Dissected long-styled flower; K. Dissected short-styled flower; L. Capsule. Scale bars: C=5 cm, E=1 cm, F–G, J–K=0.5 cm, L=1 mm.

FIGURE 2. Hedyotis dinganensis sp. nov. A. Habit; B. Stipule; C. Leaf; D. Flower bud; E. Flower; F. Corolla of long-styled; G. Corolla of shorter styled.