Rhamnus nigricans Hand.-Mazz., Anz. Akad. Wiss. Wien. Math.-Naturwiss. Kl. 62: 234-235. 1925.

Yang, Yi, Peng, Hua & Sun, Hang, 2021, Taxonomic revision of Sageretia (Rhamnaceae) from China I: identities of S. lucida, S. thea var. cordiformis and S. yunlongensis, with the description of a new species S. ellipsoidea, PhytoKeys 179, pp. 13-28 : 13

Rhamnus nigricans Hand.-Mazz., Anz. Akad. Wiss. Wien. Math.-Naturwiss. Kl. 62: 234-235. 1925. Fig. 1

Sageretia yunlongensis G.S.Fan & L.L.Deng, Sida 16(3): 477, f. 1. 1995. syn. nov. Type: China. Yunnan: Yunlong County, 1300 m, 26 Oct 1987, Expedition Team 161 (holotype SWFC!)

Type material.

China. Yunnan: "Beyendjing medium inter Tschuhsiung (Tsuyung) et Yungbei", 1800 m, 15 May 1915, Hand.-Mazz. 6311 (holotype WU!; isotypes A [00051422], K [K000729152]).

Description.

Evergreen vines, shrubs or small trees up to 6 m tall, dioecious. Young branches yellowish-brown pubescent; old branches scattered with tuberculate lenticels. Leaves alternate; stipules caducous; petioles 1.2-2.5 cm; leaf blades papery or thickly papery, ovate, oblong to broadly elliptic, 5-16 × 3-7 cm, abaxially puberulent or only on veins, adaxially usually glabrous, lateral veins 5-7 pairs, prominent abaxially, impressed adaxially, base rounded to subcordate, margin densely cartilaginous serrulate, apex acuminate to shortly caudate. Inflorescences axillary, spicate or paniculate, rachises up to 10 cm, puberulent. Flowers unisexual, 5-merous; pedicels 1-2 mm; sepals triangular; petals clawed. Drupes subglobose or globose, ca. 6 mm in diam., turning purple-black at maturity; pyrenes 2-3, asymmetrical, abaxially with a margined furrow extending over 3/4 of length.

Phenology.

Flowering from May to July; ripe fruits from October to December.

Distribution and habitat.

The species is distributed in southwestern China (Yunnan; Fig. 2 ). It grows in thickets on dry slope at elevation from 1300 to 2000 m.

Note.

Although the genera Rhamnus and Sageretia are similar in morphology, they distinctly differ in characters of inflorescence (fascicled, cymose racemes, or cymose panicles in Rhamnus vs. spikes or spicate panicles in Sageretia ) and fruits (basally persistent discoid calyx tube in Rhamnus vs. persistent reflexed calyx or remaining inconspicuous disk in Sageretia ). The type collection of S. yunlongensis , Expedition Team 161, has branched cymose panicles and fruits basally covered with discoid calyx tube, suggesting it belongs to Rhamnus rather than Sageretia . In fact, S. yunlongensis (Fig. 1B ) extremely resembles R. nigricans (Fig. 1A ), they share similar habit, indumentum, leaf blade shape and size, inflorescence, and fruit, and highly overlapped distribution. Thus S. yunlongensis is herein reduced to a synonym of R. nigricans .

Additional specimens examined.

China. Yunnan: Weishan Yi and Hui Autonomous County, 1500 m, 2012, Weishan Expedition Team 5329271259 (IMDY); Yongde County , 1830 m, 9 Jul 2006, E.D. Liu 170 (KUN); Shuangbai County , 1670 m, 15 Apr 1957, W.Q. Yin 747 (KUN, LBG, PE); Lushui County , 1544 m, 12 May 2005, Gaoligong Shan Biodiversity Survey 23964 (E) .

Figures

Figure 1. Type specimens of Rhamnus nigricans and its synonym A isotype of R. nigricans (K [K 000729152]) B holotype of S. yunlongensis (SWFC). A obtained from GBIF (https: // www. gbif. org /), B photographed by Y. Yang.

Figure 2. Distribution of Rhamnus nigricans, Sageretia cordiformis, S. ellipsoidea, and S. lucida. The sites were obtained from the specimen records, our field investigations and photo information in CFH and PPBC.