Taxonomic treatment
Veronicastrum wulingense G.W. Hu & Q.F. Wang sp. nov. (Figs. 1 and 2)
Type. CHINA. Hubei, Enshi Tujia and Miao Autonomous Prefecture, Xianfeng county, Pingbaying township, Pingbaying National Forest Park, Sidong Gorge, elev. 1324 m, 23 Jun, 2021, S.X. Ding, H. Jiang, F.M. Mutie, G.W. Hu PBY-346 (holotype: HIB!, isotypes: HIB!).
Diagnosis. Veronicastrum wulingense belongs to the Sect. Plagiostachys species (Chin and Hong, 1979). Morphologically, it is similar to V. axillare and V. rhombifolium, but can be distinctly differs by these diagnostic characteristics of peduncles up to 7 cm, flowers clustered densely in rachis apex and steadily ca. 2–3 cm long, and pedicels up to 2.5 mm (Table 1), which are unique in the all known Veronicastrum species of axillary inflorescences.
Description. Herbs, perennial. Rhizomes short, horizontal. Stems densely short curly hairs, up to 90 cm long, terete, without angles, basally branched, arching and rooting apically. Leaves alternate, petioles short, often purple-brown, no more than 5 mm long, with short curly hairs. Leaf blade thick papery to leathery, ovate to ovate-lanceolate, 3–12 × 2–6 cm; base rounded, rarely broadly cuneate, apex acute to shortly acuminate; margin serrations undate, irregular, cuspidate to long apiculate dentate, apex upward, or crenate. Leaf blades abaxially purple-red, sparse white pubescent to nearly glabrous on both surfaces, densely on veins; veins clear, lateral veins 4 − 6 pairs, concave on adaxial surface and convex on abaxial surface. Spicate inflorescences axillary, 4–9 cm long; peduncles 1–7 cm long, usually surrounded by several small leafy involucrate bracts in middle-upper part; flowers pedicellate to subsessile (0–2.5 mm long), densely clustered at rachis apex, steadily ca. 2–3 cm long; peduncles, rachis, and pedicels densely short curly hairs. Calyxes deeply 5-lobed, one adaxial lobe smaller, bracts and calyx lobes linear lanceolate to long subulate, conspicuously shorter than corolla, densely short ciliate. Corollas purple to purple-red, 5.5–7 mm long; corolla tubes tubular, straight, inner surface crinite; corollas equally 4-lobed, lobes all straight, actinomorphic, ovate-triangular to narrowly triangular, 2/5–1/2 of corolla length. Stamens 2, slightly to conspicuously exserted, exceeding corolla by ca. 2–3 mm long, crinite at lower middle part; anthers orange-yellow, oblong, 1–1.5 mm long; anther locules connivent, not confluent; ovaries glabrous, stigmas small and slightly dilated, styles 5–7 mm long. Capsules ovoid-globose, 3–3.5 mm long, 2-grooved, 4-valved; style, bracts, and calyx persistent. Seeds numerous per capsule, small, oblong, seed coat reticulate. Fl. Jun–Jul, Fr. Aug–Oct.
Distribution and habitat. The new species Veronicastrum wulingense is currently known only from Sidong Gorge of Pingbaying National Forest Park in the Northcentral of Wulingshan Region, Southwestern Hubei, China—its type locality. All our collections were made on the thick humus layers adjacent to rocks under broad-leaved forests by walkways, at elevations of 1200–1400 m above sea level..
Etymology. The specific epithet ‘wulingense’ refers to Wulingshan Region, where the new species is distributed. The Chinese name is ‘Wu Ling Fu Shui Cao (武陵腹水草)’.
Phenology. Based on our field surveys, the new species was observed flowering from June to July, and fruiting from August to October.
Conservation Significance. Veronicastrum wulingense is an endemic species currently only known from the type locality in China. Its distribution area is very narrow and only known few populations are known. Therefore, we recommended that this species be treated as a protected plant in China, and protect its habitat well.
The plastid genome features of Veronicastrum wulingense
The complete plastid genome of Veronicastrum wulingense is 152,370 bp in length and portrays a circular and quadripartite structure, typical of most angiosperms, including a large single-copy (LSC) region (87,034 bp), a small single-copy (SSC) region (18,492 bp), and a pair of inverted repeat (IR) regions (25,980 bp) that separate the LSC and SSC regions (Fig. 3). The GC content is 38.3% in the whole plastid genome, while that in the LSC, SSC, and IR regions are 36.5%, 32.3%, and 43.3%, respectively, which is relatively higher than the reported Veronica persica Poir. and Veronica nakaiana Ohwi. (related genus of Veronicastrum) in LSC and SSC regions (Choi et al. 2016). The GC content in IR regions is significantly higher than that in LSC and SSC, which may be due to the tRNA and rRNA genes that occupy a higher proportion of the regions and have a relatively higher GC content. A total of 132 functional genes were annotated in the plastid genome of V. wulingense and can be divided into four categories and subdivided into 18 groups (Table 2), which include 87 protein-coding genes (PCGs), 37 tRNA genes, and 8 rRNA genes (duplicated in two IR regions: 7 PCGs, 7 tRNA genes, and 4 rRNA genes). Also, 18 genes with introns were annotated, including 12 PCGs (clpP and ycf3 genes contain two introns) and six tRNA genes. Additionally, the start codon of rps19 gene transcription mutated and is non-canonical “GTG” instead of the most common “ATG”.
Table 2
List of the annotated genes in the chloroplast genomes of Veronicastrum wulingense.
Category | Groups of Genes | Name of Genes |
Self-replication | Ribosomal RNA | rrn4.5 c, rrn5 c, rrn16 c, rrn23 c |
Transfer RNA | trnA-UGC a,c, trnC-GCA, trnD-GUC, trnE-UUC, trnF-GAA, trnG-GCC, trnG-UCC a, trnH-GUG, trnI-CAU c, trnI-GAU a,c, trnK-UUU a, trnL-CAA c, trnL-UAA a, trnL-UAG, trnM-CAU, trnfM-CAU, trnN-GUU c, trnP-UGG, trnQ-UUG, trnR-UCU, trnR-ACG c, trnS-UGA, trnS-GCU, trnS-GGA, trnT-GGU, trnT-UGU, trnV-UAC a, trnV-GAC c, trnW-CCA, trnY-GUA |
Small subunit of ribosome | rps2, rps3, rps4, rps7 c, rps8, rps11, rps12 a,c, rps14, rps15, rps16 a, rps18, rps19 |
Large subunit of ribosome | rpl2 a,c, rpl14, rpl16 a, rpl20, rpl22, rpl23 c, rpl32, rpl33, rpl36 |
RNA polymerase subunits | rpoA, rpoB, rpoC1 a, rpoC2 |
Photosynthesis | Photosystem I | psaA, psaB, psaC, psaI, psaJ |
Photosystem II | psbA, psbB, psbC, psbD, psbE, psbF, psbH, psbI, psbJ, psbK, psbL, psbM, psbN, psbT, psbZ |
Subunits of cytochrome | petA, petB a, petD a, petG, petL, petN |
ATP synthase | atpA, atpB, atpE, atpF a, atpH, atpI |
NADH-dehydrogenase | ndhA a, ndhB a,c, ndhC, ndhD, ndhE, ndhF, ndhG, ndhH, ndhI, ndhJ, ndhK |
Other genes | Rubisco large subunit | rbcL |
Translational initiation factor | infA |
Maturase K | matK |
Envelope membrane protein | cemA |
Acetyl-CoA carboxylase | accD |
Proteolysis | clpP b |
Cytochrome c biogenesis | ccsA |
Unknown | Conserved open reading frames | ycf1, ycf2 c, ycf3 b, ycf4, ycf15 c |
Note: a, genes with one intron; b, genes with two introns; c, two gene copied in IR regions. |