Nymphanthus calcicola S.R. Yi & Gang Yao, 2022

Yao, Gang, Huang, Ya, Chen, Hongyuan & Yi, Sirong, 2022, Nymphanthus calcicola (Phyllanthaceae) - a new species from Southeast Chongqing, China, Phytotaxa 552 (1), pp. 84-90 : 85-88

Nymphanthus calcicola S.R. Yi & Gang Yao , sp. nov. ( Figs. 1‒2 )

Diagnosis: Nymphanthus calcicola is most similar to N. bodinieri (H. Lév.) R.W. Bouman in morphology, but differs from the latter by having cylindrical and twisting branchlets (vs. angled and straight branchlets), triangular-subulate stipules (vs. triangular stipules), larger flowers (female flowers that are 6.5–8.0 mm in diameter and male flowers 5.5–6.5 mm in diameter) (vs. female flowers that are ca. 4 mm in diameter and male flowers 4–4.5 mm in diameter), longer pedicles of male flowers (10–20 mm long vs. 3–7 mm long), depressed globose ovary (vs. globose ovary), deeply bifid stigmas (vs. shallowly bifid stigmas), and obscurely grooved fruits (vs. 6-groovded fruits).

Type: — CHINA. Chongqing: Pengshui county, Hanjia town, Guankou village , 108°13′″E, 29°19′N, 325 m a.s.l., under the damp forest of limestone hills, 29 February 2020, YSR 8430 (holotype, IBSC; isotypes, KUN, PE) .

Description: Shrubs, 30–60 cm tall, dioecious, glabrous; stems cylindrical, brownish; branchlets cylindrical, twisting, reddish-brown, 10–30 cm long, swollen at junction with stem. Leaves distichous, 4–8 pairs along each branchlet; leaf blades elliptic to lanceolate, 2.7–5.0 × 1.3–2.0 cm, thick papery to subleathery, margin slightly revolute, apex acuminate to acute, base broadly cuneate to slightly round, adaxially green, abaxially pale; midrib adaxially inconspicuous, abaxially slightly raised; lateral veins 5–7 pairs, adaxially obscurely, adaxially evidently; petioles 0.5–2.2 mm long; Stipules triangular-subulate, 2.5–3.5 mm long, 1.2–1.5 mm wide basely, reddish brown. Inflorescence an axillary fascicle. Male flowers up to 15-clustered, 5.5–6.5 mm in diameter, pedicels slender, glabrous, yellow-green to pale pink, 1.0–2.0 cm long; sepals 4, triangular, 2.5–3.0 × 2.5–3.0 mm, apex acute, margin entire or microwave; disc glands 4, reniform, 1.5–1.8 × 0.8–1.0 mm, margin entire; stamens 4, filaments connate at base, anthers 4, 1-locular, dehisced horizontally. Female flowers usually solitary or rarely 2–5-clustered, 6.5–8.0 mm in diameter, pedicels 1–2 cm long, pink, smooth and glabrous; sepals 6, in 2 series, broadly ovate-triangular, 2.3–2.6 × 2.5–3.0 mm, apex acute, margin entire or microwave; disk glands 6, reniform, 1.2–1.4 × 0.7–0.9 mm, margin entire; ovary depressed globose, glabrous, 1.2–1.5 mm in diameter, 0.8–1.0 high, 3-loculus, ovules 2 per loculus; style 3, free; stigmas deeply bifid nearly to the base, lobes 0.5–0.6 mm, glabrous. Capsule subglobose, 4.0– 4.5 mm in diameter, yellowish-brown, calyx persistent; seeds 6, 2.2–2.5 × 1.2–1.6 mm, reniform-triangular, laterally compressed.

Phenology: —Flowering from February to March and fruiting from May to June.

Etymology: — Nymphanthus calcicola is named after its habitat, which is characterized by the calcareous substrates in limestone hills.

Chinese name: —Hui Yan Ye Xia Zhu (灰岩叶下t)

Habitat and distribution: — Nymphanthus calcicola is found only in Ludugou , Guankou village , Hanjia town , Pengshui county, Chongqing, China ( Fig. 3 ). It grows under the damp forest of limestone hills, at the elevation of 275‒350 m. It is considered as Critically Endangered (CR) according to current information and the IUCN Red List criteria ( IUCN Standards and Petitions Committee, 2019) for it is only found from the type locality of less than 2 km 2 according to the current investigation results .

Taxonomic discussion: —Morphologically, the new species has 4 sepals in staminate flowers ( Fig. 1G & H ), 4 stamens ( Fig. 1G & M ), connate filaments ( Fig. 1M ) and horizontally dehisced anthers ( Fig. 1M ), indicating that it is a member of Nymphanthus . The new species Nymphanthus calcicola resembles N. bodinieri ( Fig. 2 ), a species distributed in Chongqing and Guizhou province, China ( Fig. 3 ). However, Nymphanthus calcicola is a dioecious shrub and has cylindrical and twisting branchlets ( Fig. 1B & F ), leaf blades that are acuminate or acute at apex and broadly cuneate to slightly round at base ( Fig. 1A–F ), inconspicuous midrib not raised adaxially ( Fig. 1A, B, D & F ), triangular-subulate stipules, female flowers that are 6.5–8.0 mm in diameter ( Fig. 1I–J ) and male flowers 5.5–6.5 mm in diameter ( Fig. 1G–H ), longer pedicels of male flowers that are 10–20 mm in length ( Fig. 1B–C ), oblate-spherical ovary ( Fig. 1N ), stigmas that are deeply bifid near to the base ( Fig. 1I & L ), and obscurely grooved fruits ( Fig. 1K ). In contrast, the similar species N. bodinieri ( Fig. 2 ) is a monoecious shrub and has angled and straight branchlets, leaf blades that ate caudate-acuminate at apex and cuneate at base, visible midrib raised adaxially, triangular stipules, smaller female flowers that are ca. 4 mm in diameter and male flowers 4–4.5 mm in diameter, shorter pedicels of male flowers that are not longer than 10 mm, ovary globose, stigmas that are shallowly bifid to less than 1/2 the length of style, and fruits that are 6-groovded ( Li & Gilbert 2008).

Figures

FIGURE 1 Nymphanthus calcicola S.R. Yi & Gang Yao.A‒C. Male plant; D‒F. Female plant; G‒H. Male flower; I‒J. Female flower; K. Fruits; L. Disk glands and pistil of female flower; M. Disk glands and stamens of male flower; N. Ovaries and styles; O. Seeds. (based on the type materal, photoed S. R. Yi)

FIGURE 2 Holotype (E.M. Bodinier 2194; E-00327392) of Nymphanthus bodinieri (Levl.) R.W. Bouman. Female flowers inserted at upper part of branchlets, male flowers inserted at lower part of branchlets.

FIGURE 3 Distribution map of Nymphanthus calcicola S.R. Yi & Gang Yao (red circular) and Nymphanthus bodinieri (Lévl.) R.W. Bouman (blue square).