Erythroxylum austroguangdongense C. M. He, X. X. Zhou & Y. H. Tong, 2022

He, Chun-Mei, Zhou, Xin-Xin, Ye, Xue-He, Chen, Weijun & Tong, Yi-Hua, 2022, Erythroxylum austroguangdongense (Erythroxylaceae), a new species from Guangdong, China, PhytoKeys 202, pp. 133-138 : 133

Erythroxylum austroguangdongense C. M. He, X. X. Zhou & Y. H. Tong sp. nov.

Fig. 1

Type.

China. Guangdong Province: Taishan, Chaliao Ao , 22°12'54.87"N, 112°57'34.84"E, 563 m a.s.l., 3 April 2021 (fl.), Xin-Xin Zhou & Yue-Yao Liu LSX303 (holotype: IBSC, isotypes: IBSC) .

Diagnosis.

Most similar to E. calyptratum Komada & Tagane in having reddish brown to grayish brown branches with dense lenticels, and white petals with appendages, but distinguished by the leathery (vs. thinly chartaceous) leaf blade with fewer pairs of secondary veins (6-8 pairs vs. 11-15 pairs), and flowers borne on leafless nodes of the basal part of current branch (vs. in leaf axils) with longer pedicels (1-1.5 cm vs. 5.2-7 mm) and sub-rectangular petal appendage (vs. bilobed appendage with each lobe consisting of a short anterior auricle and a large posterior auricle). A more detailed comparison of the two species is shown in Table 1 .

Description.

Shrubs deciduous, 1.5-2 m tall, dioecious. Young branches greenish, old branches reddish-brown to grayish-brown, lenticellate. Stipule triangular to narrowly triangular, 1.8-3 × 0.7-0.8 mm, margin entire when young, gradually fimbriate, or dissected, caducous when old. Leaves alternate, simple; petiole 3.5-6 mm long; blade elliptic or lanceolate, 4-7.7 × 1.6-2.5 cm, leathery, apex acuminate, acumen to 5 mm long, base cuneate or attenuate, margin entire, dark green and shining adaxially, pale green abaxially, midrib sunken adaxially, prominent and pale yellow to brownish-yellow abaxially, secondary veins 6-8 pairs, almost flat, faintly visible on both surfaces, tertiary veins reticulate, obscure adaxially, slightly visible abaxially. Flowers solitary on leafless nodes of the basal part of current branch, pedicel 1-1.5 cm long; bracteole triangular, ca. 0.8 mm long, margin fimbriate or serrately dissected; calyx 1.6-1.8 mm long, lobes 5, ovate-triangular, ca. 1 mm long, apex brownish, acute; petals 5, white, oblong, 3.7-4 mm long, apex obtuse or rounded, adaxially with one appendage attached ca. 1.5 mm above from base, appendage sub-rectangular, ca. 1.6 × 1 mm, papillate throughout, slightly concave on both upper and lower margin. Stamens or staminodes 10. Male flowers: stamens with different length of filaments arranged alternately, short filaments ca. 3.7 mm long, long ones ca. 4 mm long, all basally connate into a tube, tube ca. 2 mm long, densely covered with papillary trichomes; anthers ca. 1.1 mm long; sterile pistil ca. 4 mm long. Female flowers: staminodes ca. 1.2 mm long, staminodal tube ca. 1 mm long, anther absent; ovary ellipsoidal, 2-2.5 mm long, 1-1.3 mm in diam., 3-locular, with 1 fertile locule, styles 3, entirely free at base, ca. 1 mm long including stigma, stigma clavate, ca. 0.5 mm long, reflexed, with papillae. Young fruits green, turning to yellowish, ripening red, ovoid to reniform, apex oblique, 7-9 × 2.5-3 mm.

Etymology.

The species epithet is named after the distribution area of this new species, South Guangdong.

Vernacular name.

南粤古柯 (Chinese pinyin: nán yuè gŭ kē).

Distribution and habitat.

This species is currently known only from Guangdong Province, China. Three populations are found in Yangchun ( E’huangzhang), Zhuhai (Fenghuang Mountain) and Taishan (Gudou Mountain) respectively. It grows in evergreen broadleaved forests at elevations of 170-800 m.

Conservation Status.

According to the field observation, the number of mature individuals of Erythroxylum austroguangdongense is less than 100. Thus, it is assigned a status of ‘Endangered’ (EN) following the IUCN Red List categories and criteria ( IUCN Standards and Petitions Committee 2022). Since most of its distribution area is under the protection of E’huangzhang Natural Reserve and Gudou Mountain Natural Reserve, and it is not economically valuable, the threat risk seems to be low.

Phenology.

Flowering in March-April and fruiting in April-August.

Additional specimens examined (paratypes).

China. Guangdong, Taishan: Banyuzui, 448 m a.s.l., 28 March 2019 (fl.), Lei Jiang, Jin-Fan Lin, Jin-Ye Feng, Fu-Jun Chen & Jie-Lin Chen GDS-00291 (IBSC); Chaliao Ao, 205 m a.s.l., 25 April 2019 (fr.), Teng-Hui Guo, Jin-Fan Lin & Jia-Ming Chen GDS-00484 (IBSC); ibid., 19 May 2019 (fr.), Taishan Expedition 440781190519024LY (IBSC). Yangchun: Bajia, Xianjiadong Reservoir, 800 m a.s.l., 1 August 2001 (fr.), Hua-Gu Ye 6094 (IBSC); Bajia Reservoir, 750 m a.s.l., 5 August 2001 (fr.), Hua-Gu Ye 6199 (IBSC). Zhuhai: Fenghuang Mountain, 177 m a.s.l., 2 April 2021 (young fr.), Yi-Hua Tong, Wei-Jun Chen & Feng Ling TYH-2526 (IBSC); ibid. 20 March 2022 (fl.), Wei-Jun Chen TYH-2561 (IBSC).

Figures

Figure 1. Erythroxylum austroguangdongense A flowering branches B leafy branches C female flowers D male flower E stipule, showing fimbriate margin F flower bud, showing calyx G petals, adaxial (left), lateral (middle) and abaxial (right) view H androecium I staminodes and pistil J cross section of ovary, showing one fertile locule (low right) K-L fruits. Scale bars: 3 mm (H); 2 mm (E-G, I); 1 mm (J). Photographs A-B by Xin-Xin Zhou D, K by Wei-Jun Chen H by Xue-He Ye and others by Chun-Mei He.