Research Article |
Corresponding author: Xingjin He ( xjhe@scu.edu.cn ) Academic editor: Peter de Lange
© 2017 Qunying Xiao, Jinbo Tan, Haoyu Hu, Songdong Zhou, Xingjin He.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Xiao QY, Tan JB, Hu HY, Zhou SD, He XJ (2017) Semenovia gyirongensis (Apiaceae), a new species from Xizang, China. PhytoKeys 82: 57-72. https://doi.org/10.3897/phytokeys.82.13010
|
Based on morphology and molecular data, a new species Semenovia gyirongensis Q.Y.Xiao & X.J.He, from Gyirong County, Xizang, China, is described and illustrated. It is morphologically most similar to S. malcolmii (Hemsley & Pearson) Pimenov, but differs in its cylindric much-branched root, intensively branching long underground caudex with distinct nodes, narrowly ovate to ovate terminal leaf lobes, oblong bracts with obtuse-rounded or cuneate apex.
Apiaceae , new species, pollen, Qinghai-Tibetan Plateau, Semenovia , taxonomy
Semenovia Regel & Herder (Apiaceae, tribe Tordylieae), an endemic Asiatic genus, occurs in southwest, central and east Asia, with its center of diversity in the Pamir mountains (
According to morphological data, the genus Semenovia clearly differs from closely related genera Tordyliopsis DC. (well-developed, broad leafy bracts and bracteoles), Zosima Hoffm. (strongly inflated and broadly winged marginal ribs, dorsal vittae occupying furrows completely), Kandaharia Alava (very short styles, up to 0.5 mm long, strongly inflated and broadly winged marginal ribs, numerous commissural vittae), and Pastinacopsis Golosk (vallecular and commissural vittae obsolete) (
During examining specimens of Semenovia, we encountered one collection (Z. Y. Wu et al. 75-0676, stored in HNWP, KUN and PE), which was collected from Gyirong County, Xizang, China and was unable to identify as any described species. In August 2016, we carried out field investigation to the exact locality and gathered both flowering and fruiting plant from the natural population. After thoroughly consulting relevant literatures (e.g.
Related specimens deposited in C, CDBI, HNWP, K, KUN, NAS, PE, SZ, XJA and XJBI were studied. Protologues and images of type specimens were gathered fromTropicos (http://www.tropicos.org), JSTOR Global Plants (http://plants.jstor.org) and the International Plant Names Index (http://www. ipni.org). Herbarium acronyms followed
Sampling was conducted from type localities of S. gyirongensis (Gyirong County, Xizang) and S. malcolmii (Shuanghu, Nyima County, Xizang) during 2015–2016. Photographs in the field were made using a Nikon D7100 camera. The measurements of the morphological features were conducted using a vernier caliper. Mericarps were photographed using stereomicroscope Nikon SMZ 25 (Japan). Fruits from formaldehyde-acetic acid-alcohol (FAA) preserved material were used in the anatomical study. Pollen was examined from anthers collected directly in the field. The pollen grains were mounted on clean aluminum stubs using conducting carbon adhesive tabs, coated and then scanned with a JSM-7500F scanning electron microscope (SEM). General terminologies for this study followed
Total genomic DNA was extracted from silica gel-dried leaves and herbarium materials according to the protocols of plant genomic DNA kit (Tiangen Biotech, Beijing, China). The internal transcribed spacer (ITS) and external transcribed spacer (ETS) of nuclear ribosomal DNA (nrDNA) were used for phylogenetic inference based on the previous study (
62 accessions were obtained from GenBank for the nrDNAITS and ETS, and 4 were newly sequenced for this study (Suppl. material
SeqMan (
S. gyirongensis is a perennial polycarpic herb with very dense ribbon shaped hairs throughout, having cylindric much-branched roots, intensively branching long underground caudex with distinct nodes, covering rigid imbricate perished leaf sheaths and petioles, simple or sparingly branched stems, 2–3-pinnate leaves, narrowly ovate to ovate terminal leaf lobes, oblong bracts (minute), narrowly long-ovate bracteoles (2–4 mm), 5–10 rays, long styles (2.5–3 mm), mericarps elliptic or broadly elliptic, 4–7 mm long, thinly and narrowly winged marginal ribs, 4 dorsal vittae, and 2 commissural vittae (reaching 1/4 mericarp length) (Fig.
Semenovia gyirongensis A–B Habitat C Abaxial surface of primary pinnae D Basal leaf sheaths E Middle-upper cauline leaf sheaths F Rays G Adaxial surface of primary pinnae, showing hairs H Compound umbel I Umbellule J Bracts K Calyx teeth and stylopod L Infructescence M Dorsal side of mericarp N Commissural side of mericarp O Cerebroid ornamentation on equatorial plane of pollen grain P Tricolporate Q Rounded pollen polar ends.
These characters of S. gyirongensis allow for easy discrimination from morphologically similar species S. malcolmii (fusiform unbranched roots, unbranched to much-branched, short overground or emergent caudex, without distinct nodes, linear to narrowly long-ovate terminal leaf lobes and linear to narrowly ovate bracts, apex acute, Fig.
Diagnostic morphological characters of Semenovia gyirongensis (A1–A6) in comparison to the similar species Semenovia malcolmii (B1–B6) A1–B1 Habitat A2 Oblong minute bracts, apex obtuse-rounded or cuneate B2 linear to narrowly ovate bracts, apex acute A3 narrowly ovate to ovate ultimate leaf lobes B3 linear to narrowly long-ovate ultimate leaf lobes A4 Long-branched underground caudex with distinct nodes B4 Short-branched overground or emergent caudex A5 Cylindric and much-branched root B5 Fusiform and unbranched root A6 Ellipsoidal pollen grains B6 Equatorially constricted pollen grains.
Main morphological difference between Semenovia gyirongensis and its morphological allies.
Charactes | S. gyirongensis | S. malcolmii | S. pamirica | S. vachanica |
---|---|---|---|---|
Hairs | very dense | sparse or dense | dense | dense |
Root | cylindric, much-branched | fusiform, unbranched | incomplete material | incomplete material |
Caudex | underground, much-branched, long branches, with distinct nodes | overground or emergent, unbranched to much-branched, short branches, without distinct nodes | overground or emertent, much-branched, short branches, without distinct nodes | underground, much-branched, long branches, without distinct nodes |
Stem | simple or sparingly branched | simple or sparingly branched | much dichotomously branched | without branches or with a single branch above |
Basal leaves | 2–3-pinnate | 2–3-pinnatisect | simple-pinnate | pinnatisect |
Terminal leaf lobes | 0.5–2 mm, narrowly ovate to ovate | 0.7–5.7 mm, linear to narrowly long-ovate | 2–4 mm, linear | 0.5–2 mm, toothed |
Rays | 5–10, 1–2 cm | 4–12, 0.5–3.5 cm | 2–4, 1.5–2.5 cm | 2 – 5, 1.5–2 cm |
Bracts | minute, 0.4–1.5 mm oblong, apex obtuse-rounded or cuneate | 2–8 mm, linear to narrowly ovate, apex acute | 2–4 mm ovate-narrowly ovate, apex acute, margin white-scarious | 4–6 mm, linear-narrowly ovate, apex almost filiform, white-margined |
Commissural vittae | 1/4 length of mericarp | 1/4 length of mericarp to base | 3/4 length of mericarp | short, not reaching fruit base |
The matrix of combined nrDNAITS and ETS data had an aligned length of 775 positions, of which 310 were parsimony informative, 283 were constant, and 182 autapomorphic characters. The results of the ILD test for those 66 accessions common to both ITS and ETS datasets revealed that these loci yield significantly different phylogenetic estimates (P = 0.001). However, numerous reports indicated that the results of an ILD test do not adequately assess data combinability (e.g.
Phylogenetic tree inferred from tribe Tordylieae and outgroups of combined ITS/ETS dataset based on Bayesian inference (BI) method. The names of the major clades follow the study of
Based on our reconstructed phylogeny, 5 major evolutionary clades (Cymbocarpum clade, Heracleum sensu stricto clade, Semenovia clade, Tetrataenium I clade and Tetrataenium sensu stricto clade) of tribe Tordylieae were identified (Fig.
In the concatenated data sets, pairwise sequence divergence estimates for the examined taxa of the Semenovia clade ranged from 0.00% (between S. gyirongensis JL1 and JL3) to 8.01% (between Semenovia vaginata Pimenov and Zosima absinthifolia Link) with a mean value 4.4%. Sequence comparisons between the three accessions of S. gyirongensis resulted in low pairwise divergence values of 0% to 0.14%, but S. gyirongensis and its closely related species S. malcolmii (4.96–5.10%), S. pamirica (4.16–4.3%), T. brunonis (3.45–3.59%) and S. thomsonii (3.85–3.99%) yielded relatively high sequence divergence value (Suppl. material
Geographically, S. gyirongensis is close or adjacent to T. brunonis, S. pamirica, S. malcolmii and S. thomsonii but do not overlap (Suppl. material
Taking the morphology, molecular and geographical distribution evidences into consideration, it is thus clear that S. gyirongensis should be recognized as a new, distinct species of Semenovia.
China: Xizang, Gyirong County, Woma village, near Longda, 28°45.01'N, 85°18.22'E, 4023 m, 30 July 2016, xqy-20160730-01 (holotype SZ; isotypes SZ).
Semenovia gyirongensis is most similar to S. malcolmii, but can be easily distinguished by its roots (cylindric much-branched vs. fusiform unbranched), caudex (intensively branching, long, underground, with distinct nodes vs. unbranched to much-branched, short, overground or emergent, without distinct nodes), terminal leaf lobes (narrowly ovate to ovate vs. linear to narrowly long-ovate), and bracts (oblong, apex obtuse-rounded or cuneate vs. linear to narrowly ovate, apex acute).
It is also similar to the closely related species S. pamirica, but differs in stems (simple or sparingly branched vs. much dichotomously branched), rays (5–10 vs. 2–4), and commissural vittae length (reaching 1/4 mericarp length vs. reaching 3/4 mericarp length).
Herbs perennial, polycarpic, grayish-green, 8–38 cm high, very dense ribbon shaped hairs throughout, with intensively branching long (up to 40 cm) underground caudex having distinct nodes (rooting at the nodes). Root long, cylindric, much-branched. Stems simple or sparingly branched, rigid, at the base covered with straw-yellow rigid imbricate perished leaf sheaths and petioles. Basal leaves rosulate, 5–21 cm long, numerous, very dense hairs on both sides; petioles (3–15 cm) longer than or nearly equal to blades; sheaths narrowly long-ovate, lavender; blades linear or narrowly-ovate in outline, 2–3-pinnate, primary pinnae 5–8 pairs; terminal leaf lobes (0.5–2 mm, narrowly ovate to ovate). Low cauline leaves similar to basal leaves but smaller, with narrowly long-ovate sheaths; middle-upper cauline leaves gradually reduced, sessile, with soft ovate sheaths. Compound umbels with 4–10 rays (1–2 cm, sub-equal length), slightly thickened in fruit. Central umbels broader than lateral umbels, up to 3.5 cm in diameter, compact. Bracts 2–5 (minute, 0.4–1.5 mm), oblong, apex obtuse-rounded or cuneate, caducous. Umbellets 0.8–1.8 cm in diameter in fruit, 6–15 flowered; bracteoles 4–6, purplish green, narrowly long-ovate, 2–4 mm; calyx teeth small, narrowly ovate. Petals broadly obovate or narrowly ovate, adaxially whitish-yellow, abaxially purplish-yellow, puberulent on both sides, outer flowers of the umbel radiant with outer petals enlarged, unequally emaginate at the tip, with narrow lobule bent inwards. Stylopods short-conic, wavy at the margin, yellow-green, 0.3–0.5 × 0.65–0.9 mm; styles reflexed, 2–3 mm long. Fruits with slender carpophore, bifurcate to the base; mericarps strongly dorsally compressed, elliptic or broadly elliptic in outline, 4–7 × 2–5 mm, on dorsal surface densely covered by thin hairs. Dorsal ribs filiform and marginal ribs narrowly-winged (0.2–0.5 mm broad). Vittae filiform, 4 on dorsal surface (1/2–3/4 length mericarp), 2 on commissure surface (short, about 1/4 as long as mericarp).
Fruit anatomy. Exocarp is formed by one layer of small cells. Outer mesocarp layer is of thin-walled parenchyma cells; inner mesocarp (hypendocarp) is consisted of thick-walled lignified fibrous cells. Five ridges are found on each mericarp. Vascular bundles are thin in dorsal ridges, broad in marginal ridges and commissural side. There are 4 dorsally and 2 ventrally vittae. Endoderm is located as one line under the vittae and seems to be integrated with the spermoderm. The seed is composed of endosperm and spermoderm with a thickened cell wall (Suppl. material
Pollen morphology. The pollen grains are isopolar symmetric, the aperture is tricolporate type. The pollen shape is prolate with an ellipsoidal equatorial outline, the polar ends are rounded and the ornamentation is cerebroid. Polar axis (P) = 26.53 ± 0.85 µm, equatorial axils (E) = 13.43 ± 0.9 µm (n = 20) (Fig.
Phenology. The species was found flowering in July–September, fruiting in August–October.
S. gyirongensis is only known from the type locality, China, Xizang, Gyirong County, Woma village, near Longda (Suppl. material
The specific epithet is derived from the type locality, Gyirong County in Xizang, China.
Conservation status. S. gyirongensis is hitherto known only from Gyirong County (the type locality) where it usually grows on screes, rocky slopes and sandy places, locally common. In field investigation, we found that the area is subjected to overgrazing pressure and only a handful of individuals can escape from eating or trampling, ultimately blossoming and fruiting. Because of its localized distribution and grazing pressure, it should be assessed as “Vulnerable” (VU) according to the
(paratypes). China: Xizang, Gyirong County, near Longda, 5 July 1975, Z. Y. Wu et al. 75-0676 (barcode: KUN0565801!, PE 00756653!, PE 00756650! and HNWP 53717!).
We are grateful to the curators of C and K for providing and allowing reproduction of the images of herbarium specimens, and appreciate the curators of the herbaria CDBI, HNWP, KUN, PE, SZ and XJA for the permission to examine relevant specimens. We thank Dr. Min-Jie Li, Dr. Deng-Feng Xie and Mr. Xv Cui for their help in preparing this paper. Special thanks to MA. Arch. Li-Xin Ren (College of architecture and environment, Sichuan University) for line drawing and Ms. Hui Wang (Analysis and Test Center, Sichuan University) for SEM observations. This work was supported by the National Natural Science Foundation of China (Grant Nos. 31470009, 31270241, 31570198), National Specimen Information Infrastructure, Educational Specimen Sub-Platform (Web, http://mnh.scu.edu.cn/), the Science and Technology Basic Work (Grant No. 2013FY112100).
Supporting Information
Data type: species data
Explanation note: The following Supporting Information is available for this article: Figure S1–S3 and Tables S1–S2.