Hedyotis nanlingensis R. J. Wang, 2015

Wang, Ruijiang, Deng, Shujun & Huang, Xiangxu, 2015, Hedyotis nanlingensis (Rubiaceae), a new species from South China, Phytotaxa 206 (1), pp. 37-42 : 37-40

Hedyotis nanlingensis R. J. Wang , sp. nov. ( Fig. 1 )

Type: — CHINA. Guangdong province: Yangshan county, Chengjia Town, Nanling National Nature Reserve, long-styled flowers and young fruits, 24 º55’ N, 112º57’ E, 1420 m, 29 August 2012, R.- J. Wang & S.- J. Deng 2188 (holotype IBSC, isotypes IBSC).

analysis (newly generated sequences for this study are annotated with *)

Hedyotis nanlingensis is similar to H. nankunshanensis with respect to its terete stems, coriaceous and narrowly elliptic leaves, indistinct secondary venation, terminal inflorescences and diplophragmous capsules; but differs in the smaller and more slender habit, the sessile leaves, the usually two to three secondary veins on each side of the midvein, the inflorescences with monochasial branching, the shorter style in the long-styled flowers ( Table 2).

Woody perennial herbs, erect, 20–50 cm tall; stems terete, glabrous, green to deep brown. Stipules 1.5–4 × 2–4 mm, triangular, margin sparsely glandular serrate. Leaf blades sessile, narrowly elliptic, 2–8 (–10) × 0.5–2 cm, base narrowly cuneate, apex acute to acuminate, coriaceous, entire, glabrous; midvein depressed adaxially and prominent abaxially; secondary veins usually 2(–3) on each side, indistinct on both sides;. Inflorescence terminal, thyrsoid with monochasial branching at sub-axes, 4–14 cm long; peduncles 2.5–8.5 cm long, slender; bracts and bracteoles narrowly elliptic or linear, 1.5–15 × 0.2–3 mm. Flower sessile or short-pedicellate, distylous, 4-merous;. Hypanthium obconic, 1–1.5 mm long, glabrous; lobes ca. 0.8 × ca. 0.5 mm, triangular, apex acute, glabrous. Corolla white; tube 1.5–2.2 mm long, sparsely pubescent at throat; lobes oblong or narrowly elliptic, ca. 1.3 × ca. 0.6 mm, pubescent adaxially. Stamens 4, anthers oblong-linear, ca. 0.7 mm. Stigma ca. 0.5 mm, papillate, bilobed. Ovary 2-loculed, with many ovules embedded in the axile placenta. Long-styled flowers: stamens included; filaments adnate to the middle corolla tube; anthers ca. 0.5 mm; styles exserted, 2.5–3.5 mm. Short-styled flowers: stamens exserted; filaments adnate to the throat of corolla tube; anthers ca. 1 mm; styles included, ca. 1.7 mm. Capsules ellipsoid to subglobose, 2–2.5 × 1.5–2 mm, with persistent calyx lobes, glabrous, diplophragmous. Seed trigonous, ca. 0.5 mm, numerous, deep brown, with reticulate surface. Flowering occurs in Jun.–Aug. Fruiting in Aug.–Oct.

Distribution: —Known thus far only from south slope of Nanling National Nature Reserve in Yangshan County and Ruyuan Yao Autonomous County, Guangdong province, China.

Habitat and ecology:—It grows mainly in forests of Pinus kwangtungensis Chun ex Tsing , or with Dicranopteris pedata (Hout.) Nakaike ( Gleicheniaceae ), Lepidosperma chinense Nees ex Meyen ( Cyperaceae ), Sacciolepis indica (L.) Chase ( Poaceae ), Rhaphiolepis indica (L.) Lindl. ( Rosaceae ), and Rhodomyrtus tomentosa (Ait.) Hassk. ( Myrtaceae ) on dry sandy slope or roadsides, 815–1420 m.

Additional specimens examined: — CHINA. Guangdong province, Guangdong Nanling National Nature Reserve: Yangshan County, Chengjia Town , 24º55’ N, 112º57’ E, 1420 m a.s.l., 10 July 2012, R. J. Wang , 2134 ( IBSC), short-styled flower, 29 August 2012, R. J. Wang & S. J. Deng 2189 ( IBSC) ; nearby the Taipingdong village , long-styled flower and fruit, 24º52’ N, 112º56’ E, 850 m a.s.l., R. J. Wang & S. J. Deng 2202, 2205, 2206 ( IBSC) ; Liuhuali , fruiting with several flowers, 24º46’ N, 112º55’ E, 815 m a.s.l., 27 July 2013, R. J. Wang et al. 2452 ( IBSC) ; Shisankeng, 24º52’ N, 112º56’ E, 966 m a.s.l., fruiting with several flowers, 31 July 2013, R. J. Wang et al. 2467 ( IBSC). Ruyuan Yao Autonomous County, Mt. Wuzhishan , Baimakeng , 24º53’ N, 113º01’ E, 1367 m a.s.l., fruiting with several flowers, 29 July 2013, R. J. Wang et al. 2456 B ( IBSC) .

DNA barcoding analysis:—the phylogenetic analysis based on the two DNA markers revealed that H. nanlingensis is sister to H. cantoniensis with strong support (PP=100) and then together sister to H. nankunshanensis with weak support (PP=59) ( Fig. 2 ). Although the phylogenetic relationships among the above three species are not well resolved, the recognition of H. nanlingensis as a new species is supported because all accessions from each species form an separate lineage with strong bootstrap support (PP=100). H. nanlingensis is morphologically similar to H. cantoniensis in terms of leaf shape, terminal inflorescence, and diplophragmous capsules, but they differ in number of secondary veins, petiole length, flower arrangement in the inflorescence, and style length (see Table 2).

Figures

FIGURE 1. Hedyotis nanlingensis. A. Habit. B. C, D. Short-styled flower, with its style and adaxial side of the corolla, respectively. E, F,G. long-styled flowers, with its style and adaxial side of the corolla, respectively. H. Young capsule. I. Seeds, showing the abaxial (up) and adaxial (down) surface, respectively. Drawn from the holotype (long-styled flowers) and Ruijiang Wang & Shujun Deng 2189 (shortstyled flowers) by Ms Yun-Xiao Liu.

FIGURE 2. Strict consensus tree derived from a simultaneous analysis of nrITS and petD, with Bayesian Posterior Probabilities (PP) indicated above branches. The field collection number after the taxon indicates different populations or individuals.