Research Article |
Corresponding author: Shuichiro Tagane ( stagane29@gmail.com ) Academic editor: Sandy Knapp
© 2022 Shuichiro Tagane, Shinji Fujii, Shun K. Hirota, Akiyo Naiki, Tetsukazu Yahara.
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:
Tagane S, Fujii S, Hirota SK, Naiki A, Yahara T (2022) Hydrangea marunoi (Hydrangeaceae), a new species from Osumi Peninsula, southern Japan. PhytoKeys 211: 33-44. https://doi.org/10.3897/phytokeys.211.89452
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Hydrangea marunoi Tagane & S. Fujii, from the Kimotsuki Mountains in the Ohsumi Peninsula, southern Japan, is described and illustrated. It is morphologically similar to H. alternifolia in having three-petaloid calyx lobes in marginal flowers, but is distinguished by the larger stamen number, and longer styles and seeds. Multiplex ISSR genotyping by sequencing (MIG-seq) demonstrated that the new species is monophyletic and closely related to H. amamiohsimensis and H. moellendorffii rather than H. alternifolia.
Cardiandra, endemic species, flora, MIG-seq, plant taxonomy, Saxifragales
Hydrangea L., including approximately 270 natural species (
In Hydrangea sect. Cardiandra, four species, H. alternifolia L., H. amamiohsimensis (Koidz.) Y. De Smet et Granados, H. moellendorffii Hance, and H. densifolia (C. F. Wei) Y. De Smet & Granados are known from Japan, Taiwan and China (
During our floristic survey in Kagoshima Prefecture, southern Japan in 2021, we collected an unknown flowering species of Hydrangea sect Cardiandra. It is similar to H. alternifolia in appearance, but it differs from it in its habitat and some floral characters. To clarify the relationship between the unknown species and the other species of Hydrangea sect. Cardiandra in Japan, we examined the phylogenetic relationships of 52 samples of H. alternifolia, H. amamiohsimensis, H. moellendorffii, and the unknown species using multiplex ISSR genotyping by sequencing (MIG-seq,
To assess the novelty of the unknown species, we consulted the taxonomic literature (
The conservation status was calculated following the IUCN Red List categories and criteria v3.1 (
To perform the phylogenetic analysis, 52 samples of the Hydrangea sect. Cardiandra were gathered from both our field surveys in Japan and herbarium specimens deposited at the Kagoshima University Museum (KAG): 10 H. marunoi samples, two H. amamiohsimensis samples, four H. moellendorffii samples, and 36 H. alternifolia samples (Suppl. material
Total DNA was extracted from dried leaves using the cetyl trimethylammonium bromide (CTAB) method (
Maximum likelihood phylogeny based on SNPs was inferred using the RAxML 8.2.10 software (
Among the 17,753,114 raw reads (334,964 ± 34,812 reads per sample) obtained, 13,254,044 reads (250,076 ± 28,521 reads per sample) remained after quality control. After de novo SNP detection and filtering, 1875 loci and 4506 SNPs were identified. Hydrangea bifida (JPN4970) was removed from the SNP dataset because of its high proportion of missing data (0.982). The ten H. marunoi samples were monophyletic and formed two geographically defined groups; populations from Mt. Nokubi (K1658–1661) and that from the Oda River (JPN9950, JPN10103, K1633, K1637, K1638, KAG088891) (Fig.
Hydrangea marunoi is similar to H. alternifolia in having three-petaloid calyx lobes in marginal flowers but is distinguished by its higher number of stamens (28–32 stamens in H. marunoi vs.15–26 stamens in H. alternifolia), longer styles (1.2–1.8 mm long in fruiting vs. to 1.2 mm long), and longer seeds (1.2–1.5 mm long vs. 0.7–1 mm long).
Japan. Kagoshima Prefecture, Kimotsuki Town, along the Oda River, 8 Aug. 2021, S. Tagane K1637 (holotype: KAG 153198!; isotype: KYO!).
Rhizomatous perennial herb, 31–103 cm tall. Stems green in vivo, grayish-brown when dry, 3.5–6 mm in diameter near the base, puberulous when young, and subsequently glabrous. Leaves alternate, 7–11 per stem, petiolate; blades ovate, ovate-elliptic, elliptic-oblong, obovate-elliptic, (6.5–)10–28.4 × (2.5–)3.3–10.5 cm, chartaceous, sparsely pubescent to subglabrous on both surfaces, grayish-green adaxially, light pale green abaxially, apex acuminate, acumen to 2.5 cm long, base cuneate, decurrent, margin serrate, midrib slightly prominent adaxially, prominent abaxially, secondary veins 8–13 pairs, prominent abaxially, tertiary veins scalariform-reticulate, distinct abaxially; petioles 1–5 cm long, glabrous. Inflorescences terminal, or occasionally terminal and axillary on the upper stem, a corymbose cyme, 6–18 cm in diameter; bract and bracteoles leafy or narrowly lanceolate to linear, persistent. Sterile flowers (functional male flowers) with sepals 3, rarely 2 or 4, white, rarely shallowly tinged with pink, ovate, broadly ovate, suborbicular, 0.4–1.4 × 0.4–1.4 cm, apex obtuse to rounded. Fertile flowers hermaphrodite, pedicellate; pedicels 0.3–1.3 cm long, puberulous. Calyx tube cupular, 1.2–1.8 mm long, puberulous; lobes broadly triangular-ovate, 0.8–1.2 mm long, puberulous, apex rounded, margin ciliolate. Petals white, rarely shallowly tinged with pink, elliptic to suborbicular, 3.7–4.5 mm long. Stamens 28–32, 2.8–5.2 mm long, anthers 0.6–0.8 mm long, filaments 2.2–4.4 mm long, white, glabrous, flattened. Ovary fused with calyx tube, 3-locular, 22–31 ovules per locule. Styles 3, 0.9–1.1 mm long in anthesis, elongate to 1.2–1.8 mm in fruiting. Capsules ellipsoid to subglobose, 2.5–3.8 mm long, 2.2–3.5 mm in diameter. Seeds brown, 1.1–1.5 mm long (including wings); wings translucent and lighter than the seed body color.
Japan, Kagoshima Prefecture, Kimotsuki Mountains in the Osumi Peninsula (Fig.
Hydrangea marunoi usually grows on semi-shaded wet rocks along streams (Fig.
Hydrangea marunoi Tagane & S. Fujii, sp. nov. A–C habit D abaxial lower leaf surface E inflorescence F–H petaloid calyx lobes in marginal flower I flower and flower buds J calyx and styles after anthesis (petals and anthers fallen) K petals L stamens M fruits N dried fruits. Scale bars: 1 mm (K, L).
The species epithet marunoi is named after Mr. Katsutoshi Maruno, a local botanist who made significant contributions, including elucidating the flora of Kagoshima Prefecture and collecting specimens of this species, as cited earlier.
Kimotsuki kusa-ajisai (suggested here). ‘Kimotsuki’ named after the Kimotsuki Mountains in Osumi Peninsula where the species occur and ‘kusa-ajisai’ is the common Japanese name for the species of Hydrangea sect. Cardiandra.
Vulnerable (VU). Hydrangea marunoi is known from several populations in Osumi Peninsula (Fig.
The style length is one of the critical characteristics in delimiting the taxa of the Japanese Hydrangea sect. Cardiandra (
Hydrangea marunoi is endemic to the Kimotsuki Mountains of the Osumi Peninsula, located in the southernmost part of Kyushu Island. Other taxa endemic to this area include Rhododendron mayebarae Nakai et H. Hara var. ohsumiense T. Yamaz. (Ericaceae;
Japan. Kagoshima Pref. Kimotsuki Town: Kishiragoe, 12 Aug. 1916, fl., Z. Tashiro s.n. (TNS 28658); Mankuro, 9 Sept. 2008, fl., K. Maruno s.n. (KAG088530); ibid., 10 Sept. 2008, fl., K. Maruno s.n. (KAG 088557); Mt. Hoyoshi, 10 Sept. 2008, fl., K. Maruno s.n. (KAG 088561); ibid., 27 Oct. 2008, fl., K. Maruno s.n. (KAG 088641); Uchinoura, Samuta Forest Road, 6 Sept. 2009, ster. with last year’s infr., K. Maruno s.n. (KAG 088825); Uchinoura, 3 Aug. 1946, fl., I. Furusawa s.n. (TI); along Oda River, 15 Sept. 2009, fl., K. Maruno s.n (KAG 088889, KAG 088890, KAG 088891, KAG 088892, KAG 088893, KAG 088894); ibid., 8 Aug. 2021, fl., S. Fujii 19274 (KYO, TI, TNS), 19280 (KYO, TI, TNS); ibid., 8 Aug. 2021, fl., S. Tagane K1633 (KAG 153194), K1638 (KAG 153199); ibid., 4 Dec. 2021, fr., S. Tagane & K. Fuse K1828 (KAG 153605). Kinko Town: Mt. Uodake (Mt. Hassan), 15 Sept. 1988, fl., K. Maruno s.n. (KAG 156990); ibid., 25 Sept. 1988, young fr., K. Maruno s.n. (KAG 082268); Mt. Karekidake, 16 Sept. 2009, fl., K. Maruno s.n. (KAG088911); Mt. Aranishi, 5 Nov. 2009, young infl., K. Maruno s.n. (KAG 088956); Minamiosumi Town: Satahetsuka, 2 Sept. 2004, fl., Y. Morita & K. Maruno s.n. (KAP 00400106s, KAP 00400107s,); Mt. Nokubidake, fl. bud, 9 Aug. 2008, K. Maruno s.n. (KAG 088497); ibid., fl. bud, 9 Aug. 2008, T. Ohya s.n. (KAP 00800421s, KAP00800443s); ibid., 29 Sept. 2021, fl., S. Tagane K1658 (KYO), K1659 (TI), K1660 (KAG 153218) & K1661 (TNS).
In appearance, H. marunoi is more similar to H. alternifolia, typically having three-petaloid calyx lobes in marginal flowers, than to H. moellendorffii, which has two-petaloid calyx lobes or to H. amamiohsimensis without petaloid calyx lobes. However, the MIG-seq tree (Fig.
The MIG-seq tree also revealed that a clade H. alternifolia consisting of three samples JPN10093, 10106 and 10107, collected from the Sea of Japan (western) side of Honshu Island (yellow squares in Fig.
1 | Leaves sparsely scattered along stem, alternate | 2 |
– | Leaves distally on stem, usually 4–8 fascicled [China (Zhejiang), Taiwan] | H. densifolia |
2 | Petaloid calyx lobes in marginal flowers present | 3 |
– | Petaloid calyx lobes in marginal flowers absent [Japan (Amami-Oshima Island)] | H. amamiohsimensis |
3 | Petaloid calyx lobes in marginal flowers 3 (rarely 2 or 4) [Japan (Honshu, Shikoku, Kyushu)] | 4 |
– | Petaloid calyx lobes in marginal flowers 2 (very rarely 3) [China, Japan (Iriomote Island)] | H. moellendorffii |
4 | Stamens 15–26; styles to 1.2 mm long in fruiting; seeds 0.7–1 mm long [Japan (Honshu, Shikoku, Kyushu)] | H. alternifolia |
– | Stamens 28–32; styles 1.2–1.8 mm long in fruiting; seeds 1.2–1.5 mm long [Japan (Kyushu: Kimotsuki Mountains)] | H. marunoi |
We thank Kaya Shimizu and Hironori Toyama for assisting with sampling materials and Ai Nagahama for providing a specimen image of H. marunoi at TNS. We also thank the curators and staff of the following herbaria: FKSE, FU, KAG, KAP, TI, TRPM, and Shimane Nature Museum of Mt. Sanbe for making their materials accessible. We would like to thank Editage (www.editage.com) for English-language editing. This study was supported by the Environment Research and Technology Development Fund (JPMEERF20204001 and JPMEERF20204003) of the Environmental Restoration and Conservation Agency provided by the Ministry of Environment of Japan, JSPS KAKENHI grant number 21K06307, and a University of the Ryukyus Research Project Promotion Grant (Strategic Research Grant) (No. 17SP01302).
Table S1
Data type: sample list
Explanation note: Sample list used for phylogenetic analysis in this study.