﻿Artemisiaqingheensis (Asteraceae, Anthemideae), a new species from Xinjiang, China

﻿Abstract Artemisiaqingheensis (Asteraceae, Anthemideae), a new species from Qinghe County, Xinjiang, China, is described and illustrated. We investigated its phylogenetic position and relationships with 35 other species of Artemisia using whole chloroplast DNA sequence data. The molecular phylogenetic results and morphological evidence (multi-layered involucral bracts and homogamous capitula with bisexual flowers) showed that the new species belongs to ArtemisiasubgenusSeriphidium. A diagnostic table and discussion of morphological characters are provided to distinguish the new species from A.amoena, A.gracilescens, A.lessingiana and A.terrae-albae.

Subgenus Seriphidium, comprising ca. 130 species, is one of the most diverse subgenera and is mainly distinguished from the others by its multi-layered involucral bracts and homogamous capitula with bisexual flowers (Ling 1991). Subgenus Seriphidium grows mainly in arid and semi-arid regions in Central Asia and Northwest China (Malik et al. 2017). Thirty-one species and six varieties have been recorded in China (Ling et al. 2011).
During a field expedition in the north-eastern region of the Junggar Basin, located in Xinjiang, China, in 2020, a new population of Artemisia from Qinghe County was discovered. After consulting "Flora of China" (Ling et al. 2011) and other relevant literature (Poljakov 1961;Filatova 1966Filatova , 1986Filatova , 1993Filatova , 2007Ling 1991;Liu 1992;Wei 1999), and after comparing the plants of this population with those of morphologically similar species (Besser 1841;Krascheninnikov 1930;Krascheninnikov and Iljin 1949;Poljakov 1954), we revisited this site at different times in 2021 and 2022 to carry out further observations and sampling with the aim of determining the taxonomic identity of the new population. Following additional morphological and molecular phylogenetic analyses, we concluded that it is different from all other known species of Artemisia. Hence, it is here described and illustrated as a new species: A. qingheensis.

Material and method
After examining the worldwide list of subg. Seriphidium species and their type specimens (Jin 2023), we critically examined specimens (including type material) of A. gracilescens Krasch. & Iljin, A. lessingiana Besser, and A. terrae-albae Krasch. in IBSC, LE, LECB, MW, PE, TK, TASH and XJBI. These species are morphologically most similar to the new taxon.
Chloroplast genomes of 36 Artemisia species from four subgenera, including 17 subg. Seriphidium species, were used for phylogenetic analysis (Fig. 1). The closely related species Ajania pacifica (Table 1) was used as the outgroup (Watson et al. 2002). We included 38 samples in our phylogenetic analyses, 36 of them were obtained from NCBI (https://www.ncbi.nlm.nih.gov/) and two were newly sequenced for this study: A. lessingiana and A. qingheensis (Table 1). For both, we extracted total genomic DNA from approximately 100 mg of silica gel-dried leaf material using a modified CTAB method (Doyle and Doyle 1987). Voucher specimens (A. qingheensis: No. jgz-099-4;A. lessingiana: No. jgz-20220529) were deposited in the Herbarium of the Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences (XJBI). DNA extracts were fragmented for short-insert library construction (300 bp) and sequenced (2 × 150 bp paired-end reads) on DNBSEQ technology platforms at the Beijing Genomics Institute (Shenzhen, China). The raw reads were assessed and edited using FastQC 0.11.5 (http://www.bioinformatics.babraham.ac.uk/projects/fastqc/) and Trimmomatic 0.35 (Bolger et al. 2014) was used to remove adapters and low quality bases. Finally, a ca. 3 G bp paired-end clean read was obtained for each sample. The clean data was assembled with GetOrganelle v. 1.7.1 (Jin et al. 2020). The complete circular assembly graph was checked using Bandage v. 0.8.1 (Wick et al. 2015). The finished plastid genomes were annotated with Geneious v. 9.1.7 (Kearse et al. 2012). The annotated plastid genomes were submitted to GenBank using Bankit (Table 1).
Genomes were aligned in MAFFT v. 7 (Katoh and Standley 2013). According to the Akaike Information Criterion (AIC), the most appropriate substitution model for the complete chloroplast genome sequence matrix, estimated using jModelTest2 (Darriba et al. 2012), was GTR + I + G. Bayesian Inference (BI) analysis was carried out using MrBayes v.3.2 (Ronquist et al. 2012

Taxonomic treatment
Distribution and habitat. Artemisia qingheensis is currently only known from Qinghe County, Xinjiang Province, China. It grows on barren slopes at altitudes of 1000 ~ 1500 m.
Etymology. Artemisia qingheensis is named after its type locality, Qinghe County, Xinjiang Province, China.
Phenology. Flowering and fruiting from early September to late October. Vernacular name. 青河绢蒿 (Chinese pinyin: qīng hé juàn hāo). This name is derived from the Chinese name of the type locality.
Conservation status. Although field surveys have been conducted in the north-eastern region of the Junggar Basin over a period of three years, we have only discovered three populations of Artemisia qingheensis in Qinghe County. Unfortunately, as these populations are next to roads and agricultural land, habitat quality is continuously declining due to man-made interference (e.g. grazing, cultivation and landscape engineering). The possible deterioration of its habitat and the restricted distribution of this species threaten its survival. According to the Guidelines for using the IUCN Red List Categories and Criteria (IUCN 2022), the conservation status of A. qingheensis should be assessed as Critically Endangered (CR, B1ab).
Phylogenetic position and similar species. Artemisia qingheensis belongs to Artemisia subg. Seriphidium because its involucrum is multi-layered, its capitula are homogamous and contain 3-6 bisexual flowers, and these open centrifugally. In addition, our phylogenetic analysis confirmed the inclusion of this new species in subg. Seriphidium. Artemisia qingheensis is similar to A. terrae-albae in its habit, leaf shape, petiole length, capitula shape and corolla colour. However, it can be clearly distinguished from A. terrae-albae (Fig. 4) because its branches grow adnate to the stem (vs. obliquely upward or spreading) and its leaves harden when maturing (vs. leaves slightly soft when mature). This new species is also relatively easy to distinguish from A. lessingiana by its shorter petioles 0.3-1 cm (vs. 2-5 cm) and ovate (vs. oblong-ovate) leaf blade.
The new species is similar to A. gracilescens in its habit and narrowly spicate or spicate-paniculate inflorescences. However, it is mainly distinguished from A. gracilescens by its 2-pinnatisect lowermost leaves and ovate leaf blade (vs. 2-or 3-pinnatisect and leaf blade triangular-ovate), middle stem leaves 1-pinnatisect (vs. usually 1-or 2-pinnatisect), uppermost leaves three-lobed or undivided (vs. 1-or 2-pinnatisect), all leaves hardening when maturing (vs. leaves slightly soft when mature) and ovoid capitula (vs. ellipsoid). Furthermore, this species is also somewhat similar to A. amoena Poljakov in its habit and capitula, which are borne in spikes or narrow panicles, but is distinguished by its shorter petioles 0.3-1 cm (vs. 4-8 cm), longer stem branches: 3-15 cm vs. 2-3 cm, and the hardening of the leaves when these mature (vs. leaves slightly soft when mature).