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Review Article
Artemisia calcicola (Asteraceae, Anthemideae), a new species from karst region in Guizhou, southwestern China
expand article infoCheng-Sheng Li§, Xiao-Rui Chi§, Xin-Qiang Guo|, Long Wang
‡ South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
§ University of Chinese Academy of Sciences, Beijing, China
| Hangzhou Normal University, Hangzhou, China
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Abstract

Artemisia calcicola (Asteraceae, Anthemideae), a new species from karst region in Shibing county, Guizhou province, southwestern China, is described and illustrated. The species can be readily assigned to A. subg. Artemisia in having fertile disk florets and glabrous receptacles. Within this subgenus, A. calcicola is distinguished by having (2- or) 3-pinnatipartite leaves and narrowly ellipsoid involucres 0.9–1.3 mm in diameter. It resembles A. annua to some extent, but differs immediately by the plant duration, stem and leaf indumentum, and involucre shape and size. A detailed description and distribution map of this species are also provided herein.

Keywords

Compositae, limestone flora, morphology, taxonomy

Introduction

Artemisia L. (Asteraceae), the largest genus of the tribe Anthemideae, comprises 300–500 species mainly distributed in the northern hemisphere (Ling 1991; Shulz 2006; Ling et al. 2011; Pellicer et al. 2014, 2018; Malik et al. 2017). China is considered one of the most important species centers of this genus, with ca. 190 species and 40 varieties recorded (Ling 1988, 1991; Ling et al. 2011; Shultz and Boufford 2012; Guo et al. 2020, 2021, 2022). This genus is well known for containing various remarkable bioactive compounds, especially the efficient antimalarial agent artemisinin extracted from the leaves of A. annua L. (Tu 2011, 2017; Pellicer et al. 2018).

During a botanical trip to Guizhou in southwestern China in 2021, we discovered an unusual population of Artemisia in a karst region in Shibing (Fig. 1). At first glance, the plants were easily referred to A. subg. Artemisia due to their fertile disk florets and glabrous receptacles. Further critical observations revealed that they are rather distinct within this subgenus by having (2- or) 3-pinnatipartite leaves and narrowly ellipsoid involucres 0.9–1.3 mm in diameter. Morphologically, they are superficially similar to A. annua, a species in the same subgenus and widely distributed in the northern hemisphere, in having (2- or) 3-pinnatipartite stem leaves, ovate-acuminate or ovate, entire or (1- or) 2-toothed leaf lobules, and a narrow to broad panicle-like synflorescence (Fig. 1), but differ markedly by being perennial (vs. annual) and by having arachnoid-tomentose (vs. glabrous or sparsely pubescent) stems and leaves, narrowly ellipsoid (vs. globose or hemispheric) involucres 0.9–1.3 mm (vs. 1.5–2.5 mm) in diameter (Table 1). We therefore determined that the population in question represents a hitherto undescribed species, which we name A. calcicola and describe below.

Table 1.

Morphological comparison between Artemisia annua and A. calcicola sp. nov.

A. annua A. calcicola
Duration Annual perennial
Stem glabrous, sparsely pubescent arachnoid-tomentose
Leaf glabrous, sparsely pubescent; middle stem leaves 3 (or 4)-pinnatipartite; segments 5–8 (−10) pairs arachnoid-tomentose; middle stem leaves (2- or) 3-pinnatipartite; segments 3–6 pairs
Capitulum shortly pedunculate sessile or subsessile
Involucre globose to hemispheric; 1.5–2.5 mm in diameter narrowly ellipsoid; 0.9–1.3 mm in diameter
Marginal female floret 10–20 4–6
Disk floret 10–30; corolla yellow or dark yellow 7–9; corolla creamy yellow
Figure 1. 

Artemisia calcicola sp. nov. A habitat and habit B leaf rosette of a vegetative branch C portion of stem D leaves E adaxial side of leaf F abaxial side of leaf G portion of synflorescence H capitula I phyllaries (abaxial side) J receptacle K marginal female florets L disk florets. All photographs by Long Wang.

Materials and methods

For morphological comparison, we critically examined physical or digitalized herbarium specimens of the genus Artemisia deposited at several major herbaria in China including CDBI, HNWP, IBSC, KUN, NAS, PE, SZ, and WUK (acronyms follow Thiers (2022)). Plants of A. calcicola were collected and photographed during our 2021 field investigation to Guizhou province. Morphological observations and measurements were based on fresh materials as well as herbarium specimens deposited at IBSC.

Taxonomic treatment

Artemisia calcicola X.Q.Guo & L.Wang, sp. nov.

Figs 1, 2

Diagnosis

Artemisia calcicola is distinguished within the A. subg. Artemisia in having (2- or) 3-pinnatipartite leaves and narrowly ellipsoid involucres 0.9–1.3 mm in diameter. Within this subgenus, it is merely superficially similar to A. annua in having (2- or) 3-pinnatipartite stem leaves, ovate-acuminate or ovate, entire or (1- or) 2-toothed leaf lobules, and a narrow to broad panicle-like synflorescence, but differs by being perennial and by having arachnoid-tomentose stems and leaves and narrowly ellipsoid involucres 0.9–1.3 mm in diameter (a detailed morphological comparison between the two species is given in Table 1).

Type

China. Guizhou: Shibing, Yuntai Shan, 27°06'N, 108°06'E, calcareous cliffs, 873 m a.s.l., 12 October 2021 (fl.), Long Wang & Cheng-Sheng Li 4521 (holotype: IBSC; isotypes: IBSC, PE). Fig. 2.

Figure 2. 

Holotype sheet of Artemisia calcicola sp. nov.

Description

Herbs, perennial, 40–80 (–100) cm tall. Rhizome woody, up to 0.7 cm in diameter at base. Stems arachnoid-tomentose, more or less branched, erect or ascending. Basal stem leaves usually withered at anthesis, petiolate; (2- or) 3-pinnatipartite. Middle stem leaves petiolate; petiole 1–3 cm long; leaf blade ovate or ovate-oblong, 3–7 cm long, 3–5 cm broad, light green adaxially, grayish green abaxially, arachnoid-tomentose on both surfaces, (2- or) 3-pinnatipartite; segments 3–6 pairs, elliptic or ovate-elliptic, 1–2.5 cm long, 0.5–1 cm broad; lobes 3–6 pairs on each segment, elliptic or ovate, 5–8 mm long, 3–5 mm broad, with lobules ovate-acuminate or ovate, entire or (1- or) 2-toothed. Upper stem leaves subsessile or sessile; leaf blade ovate or ovate-elliptic, 3–5 cm long, 3–4 cm broad, (2- or) 3-pinnatipartite, arachnoid-tomentose on both sides; segments 3–7 pairs, elliptic or ovate, 1–2 cm long, 0.5–1.5 cm broad; lobes 3–5 pairs on each segment, elliptic or ovate, 0.5–1 cm long, 3–5 mm broad, with lobules ovate-acuminate or ovate, entire or (1- or) 2-toothed. Uppermost stem leaves subsessile; leaf blade ovate or ovate-elliptic, 1.5–2 cm long, 1.5–2 cm broad, (2- or) 3-pinnatipartite, arachnoid-tomentose on both sides; segments 3–6 pairs, elliptic or ovate, 0.5–1 cm long, 0.5–1 cm broad; lobes 2–4 pairs on each segment, ovate, with lobules ovate-acuminate or ovate, apex mucronate, entire or (1- or) 2-toothed. Synflorescence a narrow or broad panicle. Capitula sessile or subsessile, usually 3–7 clustered together. Involucres narrowly ellipsoid, 1.8–2.2 mm high, 0.9–1.3 mm in diameter. Phyllaries 3–4 rows, abaxially sparsely arachnoid-pubescent (outermost row) to glabrous (inner rows), obovate, ovate-oblong to elliptic, green when fresh, margin membranous. Receptacle glabrous. Marginal female florets 4–6, ca. 2 mm long, fertile; corolla tubular, 0.7–1 mm long, apex 2-toothed; style exserted. Disk florets 7–9, ca. 2 mm long, bisexual, fertile; corolla creamy yellow, 0.8–1 mm long, apex 5-toothed. Achenes cylindrical. Pappus absent.

Distribution and habitat

Artemisia calcicola is currently known only from the type locality, i.e. Yuntai Shan in Shibing, Guizhou, southwestern China (Fig. 3). It grows on calcareous cliffs at an altitude of ca. 900 m above sea level.

Figure 3. 

Distribution of Artemisia calcicola sp. nov. (black circle).

Etymology

Latin calcis, genitive singular of calx, limestone, and cola, dweller, alluding to habitat on calcareous cliffs.

Phenology

Flowering from October to November; fruiting from November to December.

Vernacular name

灰岩蒿 (Chinese pinyin: huī yán hāo).

Conservation status

Artemisia calcicola is currently known only from its type locality, i.e. Yuntai Shan in Shibing, Guizhou, southwestern China. The single population we discovered consists of no more than 20 individuals. Before acquiring adequate information to make a conclusive assessment of its risk of endangerment, the conservation status of A. calcicola is here recommended as “Data Deficient (DD)” (IUCN 2019).

Notes

In Artemisia subg. Artemisia, A. calcicola is also somewhat similar to A. lancea Vaniot, a species widely distributed in China, India, Japan, Korea, and Russia, particularly in the narrowly ellipsoid involucres. However, A. calcicola differs remarkably from A. lancea by an array of characters, including the arachnoid-tomentose (vs. glabrescent or sparsely arachnoid) stems, (2- or) 3-pinnatipartite (vs. 1-pinnatisect to 3-partite, or undivided), arachnoid-tomentose (vs. adaxially sparsely arachnoid, abaxially densely tomentose) stem leaves, and elliptic or ovate (linear-lanceolate or linear if divided) leaf segments.

Acknowledgements

We thank Dr. Qin-er Yang for his critical comments resulting in substantial improvement of the initial draft of the manuscript. We are grateful to the curators of IBSC, K, KUN, LINN and PE for allowing us to examine their specimens and for research facilities. We would also like to thank Xin-yin Ma for her help during preparation of this manuscript. This work was supported by the National Natural Science Foundation of China (grant no. 31900183) and the Biological Resources Programme, Chinese Academy of Sciences (grant no. KFJ-BRP-017-08).

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