Erythroxylum calyptratum Komada & Tagane, 2018

Komada, Natsuki, Tagane, Shuichiro, Ngoc, Nguyen Van, Binh, Hoang Thi, Son, Hoang Thanh, Toyama, Hironori, Nagamasu, Hidetoshi, Naiki, Akiyo & Yahara, Tetsukazu, 2018, Erythroxylum calyptratum (Erythroxylaceae), a new species from Mt. Fansipan, northern Vietnam, Phytotaxa 347 (4), pp. 279-284 : 280-282

Erythroxylum calyptratum Komada & Tagane , sp. nov. Figs. 1 & 2 .

Type:— VIETNAM. Lao Cai Province, Hoang Lien National Park , in lower montane evergreen forest, along trail to the summit, 22°19 ′ 59.7 ″ N, 103°46 ′ 46.3 ″ E, alt. 2159 m, 3 May 2016, with female flowers, Tagane S., Yahara T., Toyama H., Nagamasu H., Naiki A., Nguyen V.N., Hoang T.B., Hoang T.S. V 5132 (Holotype KYO!; isotypes DLU, K, P, VNM, the herbarium of Hoang Lien National Park ) .

Diagnosis:–– Erythroxylum calyptratum is most similar to E. sinense in having papery leaves, downward flowers and entirely free 3 styles but differs in shorter petiole (2–3 mm long in E. calyptratum vs. 3–8 mm long in E. sinense ), fewer flowers per inflorescence (1–3 vs. 2–7), white petals (vs. pinkish), and well-developed petal appendages (1/3–1/2 length of petals vs. 1/10–1/6).

Dioecious deciduous shrubs, 1.5–2 m tall, all part glabrous. Young branches greenish, reddish brown when dry; old branches reddish brown to grayish brown, lenticellate. Stipule narrowly triangular to lanceolate, 3–5 × 0.7–1.1 mm, margin entire when young, gradually fimbriate, or dissected, and then serrate when old. Leaves alternate, simple; petiole, subterete, 2–3 mm long; blade elliptic-lanceolate, elliptic, oblong-elliptic, or obovate-elliptic, (1.5–)3.5–9.5 × (0.6–) 1.3–3 cm, thinly chartaceous, apex acuminate, acumen to 1.0 cm long, base cuneate or attenuate, margin entire, pale green adaxially, glaucous abaxially, midrib sunken adaxially, prominent and pale yellow to brownish yellow abaxially when dry, secondary veins 11–15 pairs, almost flat, faintly visible on both surfaces, tertiary veins reticulate, obscure adaxially, slightly visible abaxially. Flowers dichlamydeous, dialypetalous, heterostylous, in the leaf axils, solitary to 3-fascicled on a very short rachis, rachis up to 1 mm long; pedicel 5.2–7 mm long; bracteole triangular, ca. 0.6 mm long, margin fimbriate or serrately dissected; calyx ca. 2 mm long, lobes 5, ovate-triangular, ca. 1.5 mm long, apex acute; petals 5, white, oblong, ca. 5 mm long, apex acute to obtuse, adaxially with 2 ligular appendages attached ca. 2 mm above from base, the appendages bilobed, 1.75–2 mm long, each lobe consisting of a short anterior auricle and a large posterior auricle, the anterior two auricles ovate-triangular, ca. 0.7 mm long, apex rounded, the posterior two auricles ovate-oblong, ca. 1.2 mm long, apex obtuse. Stamens or staminodes 10. In brevistylous flowers: filaments 3.5–4 mm long, different length of filaments lines up alternately, basally connate into a tube, tube ca. 2 mm long, densely covered with papillary trichomes; anthers 0.6 mm long; ovary ca. 0.7 mm long; style 3, entirely free at base, 0.8–1.5 mm long including stigma. In longistylous flowers: staminodes ca. 2 mm long, staminodal tube ca. 1 mm long, anther absent or very rarely present (but reduced to 0.4 mm long and no pollen inside); ovary ellipsoidal, 2.2–2.5 mm long, ca. 1.1 mm in diam., 3-locular, with 1 fertile locule, styles 3, entirely free at base, ca. 2 mm long including stigma, stigma clavate, ca. 1.2 mm long, bending backward, with papillae. Young fruits green, ripening reddish, ellipsoid.

Other specimens examined:— VIETNAM. Lao Cai Province, Hoang Lien National Park: 22°20 ′ 08.1 ″ N, 103°46 ′ 46.7 ″ E, alt. 2091 m, 2 May 2016, with male flowers, Tagane et al. V5018 (DLU, BKF, VNM, the herbarium of Hoang Lien National Park ) ; ibidem, 2 May 2016, with female flowers, Tagane et al. V5019 (BKF, DLU, the herbarium of Hoang Lien National Park ) ; 22°19 ′ 48.0 ″ N, 103°46 ′ 57.5 ″ E, alt. 2225 m, 3 May 2016, with male flowers, Tagane et al. V5097 (DLU, KYO, the herbarium of Hoang Lien National Park ) .

Distribution, habitat and phenology:— Vietnam (so far known only from Mt. Fansipan, Hoang Lien National Park). Erythroxylum calyptratum is common in lower montane forest at altitude 2100–2300 m in the Hoang Lien National Park. Flowers and young fruits were observed in the beginning of May.

Etymology:— The species epithet refers to the structure of ligular appendages of petals hidden inside and largely cover stamens or staminodes and ovary.

Threat status:— Least Concern (LC) ( IUCN 2012). Erythroxylum calyptratum is common in the lower montane forest of Mt. Fansipan in Hoang Lien National Park and the forest are well-protected.

GenBank accession no:— Tagane et al. V5018: LC310880 (rbcL), LC310883 (matK); Tagane et al. V5019: LC310881 (rbcL), LC310884 (matK); Tagane et al. V5132: LC310879 (rbcL), LC310882 (matK). In DNA database, 36 species of Erythroxylum were found (accessed 15 July 2017), among which only three species, E. cambodianum , E. cuneatum and E. sinense are Asian species obtained from Cambodia, Myanmar and China, respectively. Among the total 36 species, the BLAST similarity search based on the rbcL and matK sequence of E. calyptratum resulted in homology as high as 517/518 bp and 752/758 bp with the sequence of E. sinense (GenBank accession no. rbcL: KP090500, matK: KP094049). The sequences between E. calyptratum and E. cambodianum (GenBank accession no. rbcL: AB925614, matK: AB925186) differs 9 bp of the 508 total and 17 bp of the total 801, and those between E. calyptratum and E. cuneatum (GenBank accession no. rbcL: LC310982, matK: LC310983) differs 8 bp of the 519 total and 17 bp of the 856 total, respectively ( Table 1).

Figures

FIGURE 1. Erythroxylum calyptratum Komada & Tagane. A) Flowering branch, B) Base of a leaf showing petiole and stipules, C) Brevistylous flower, D) Longistylous flower, E) Petal with appendages, F) Young fruit, G) Transverse section of young fruit. Materials: Tagane et al. V5018 (A, B), Tagane et al. V5097 (C, E), Tagane et al. V5132 (D, F, G) (KYO). Drawn by N. Komada.

FIGURE 2. Erythroxylum calyptratum Komada & Tagane. A) Habitat, B) Flowering branch, C) Stem, D) Top branch showing stipules and abaxial leaf surface, E) Brevistylous flower F) Longistylous flower, G) Brevistylous flower, H) Longistylous flower, I) Young fruits. Photos of Tagane et al. V5018 (A–E), Tagane et al. V5097 (G), Tagane et al. V5132 (F, H, I) by S. Tagane.