Chrysosplenium insularis J. E. Jang, K. H. Lee & H. Y. Gil, 2024

Jang, Ju Eun, Park, Beom Kyun, Lee, Kang-Hyup, Kim, Hyuk-Jin & Gil, Hee-Young, 2024, Description and phylogenetic position of a new species, Chrysosplenium insularis J. E. Jang, K. H. Lee & H. Y. Gil (Saxifragaceae), from the southern islands of South Korea, PhytoKeys 248, pp. 91-104 : 91-104

Chrysosplenium insularis J. E. Jang, K. H. Lee & H. Y. Gil sp. nov.

Figs 1 , 4 A – F

Diagnosis.

Chrysosplenium insularis differs from C. japonicum in having fairly persistent bulbils, green to yellowish-green sepals, four stamens, and cylindrical papillose seeds.

Type.

Korea • Jeju, Seogwipo-si, Hogeun-dong ; 33.25084, 126.54434; elev. 58 m; 25 Mar 2020 [fl]; Kang-Hyup Lee JJ- 200325-001 [holotype KH (Fig. 2 ); isotypes, 3 sheets, KH] .

Description.

Perennial herbs, hermaphroditic, 5–15 cm tall. Bulbils present near stem base, fairly persistent, pink, turning darkish brown, pilose. Roots fibrous, white. Stems erect, cespitose, light green to green, sparsely hairy, without stolons. Basal leaves of flowering stems 1–6, opposite, simple, estipulate; petiole 3–9 cm long, glabrescent or sparsely hairy; blade reniform, 13–20 mm × 15–25 mm, apex rounded and often retuse, margins dentate to crenate, 13–17 teeth, base cordate, adaxially green, pilose, abaxially pale green, subglabrous. Cauline leaves of flowering stems 1–4, alternate, simple, estipulate; petiole 5–22 mm long, glabrescent or sparsely hairy; blade flabellate to reniform, 7–12 mm × 11–18 mm, apex retuse and often rounded or obtuse, margins dentate to crenate, 9–13 teeth, base cordate to broadly cuneate, adaxially green, pilose, abaxially pale green, subglabrous. Inflorescences terminal, 6–14 flowered cyme, surrounded by leaf-like bracts; peduncles 4.59–18.54 mm long; pedicels 0.5–1.5 mm long, sparsely pilose; bracteal leaves by inflorescence 3, petiole 0.2–4.7 mm long, glabrescent or sparsely hairy; blade subflabellate to orbicular, 2–18 × 2–14 mm, apex truncate and often retuse, margins dentate to crenate, 5–9 teeth, base broadly cuneate to subcordate, adaxially green, sparsely pilose to glabrescent, abaxially pale green, subglabrous. Flowers 4 - merous, actinomorphic; sepals petaloid 4, free, erect to subspreading, ovate to broadly ovate, 1.2–2.1 × 1.5–3.1 mm, apex obtuse or rounded, yellowish green to green, glabrous; stamens 4; filaments narrow conical, 0.3–0.4 mm long; anther 0.2 mm long, yellow; pistil 2 - carpellate, semi-inferior; ovary 1 - locular; styles 2, free, erect, 0.2–0.3 mm long; stigma round; disc present. Capsules 2 - lobed, horn shaped, lobes subequal, 2.8–3.7 × 3.8–5.2 mm long, green, glabrous, dehiscent along the adaxial suture. Seeds numerous, ovoid-ellipsoid, 0.7–0.9 × 0.5–0.6 mm, brown to dark brown, cylindrical papillose on smooth surfaces.

Phenology.

Flowering and fruiting from March to May.

Distribution and habitat.

Southern coastal regions of Korea (Jeju-do and Gageo-do Islands). Forests, wet places in forests, shaded places on the riverside (Fig. 3 ).

Etymology.

The specific epithet “ insularis ” refers to its distribution on islands.

Vernacular name.

Island golden saxifrage: Seom-gwaeng-i-nun (섬괭이눈).

Morphological assessment.

Among the species distributed in Korea, Chrysosplenium insularis is morphologically similar to C. japonicum in terms of leaf arrangement, leaf margin, and bracteal leaf color. Despite these similarities, it is clearly differentiated by the form of bulbils [present, fairly persistent (Fig. 1 B ) vs. present], surface of bracteal leaves [adaxially sparsely pilose to glabrescent, abaxially subglabrous (Fig. 4 D ) vs. mainly glabrous (Fig. 4 J )], color of sepals [green to yellowish green vs. yellowish green to yellow], number of stamens [4 vs. usually 8], and surface of seeds [cylindrical papillose (Fig. 4 E, F ) vs. papillose (Fig. 4 K, L )]. Additionally, this new species is morphologically similar to C. alternifolium , which is distributed in northern Eurasia, but is distinguished by the following characteristics: stolon (absent vs. present), color of bracts (green vs. yellow), color of sepals (green to yellowish green vs. golden yellow), number of stamens (4 vs. 8), and surface of seeds [cylindrical papillose (Fig. 4 E, K ) vs. smooth (Fig. 4 K, L )]. A comparison of the major characteristics of the new species with those of two closely related species, C. japonicum and C. alternifolium , is shown in Table 3 .

Phylogenetic analysis.

In total, 48 sequences of three regions (ITS, mat K, and rbc L) were newly obtained from the 16 accessions of Chrysosplenium insularis and the three related taxa. We also used 93 sequences from 32 accessions obtained from GenBank (12 species of Chrysosplenium and one Peltoboykinia tellimoides as an outgroup) for the phylogenetic analysis. The aligned matrix of the ITS region and combined chloroplast regions (mat K and rbc L) contained 635 and 1407 characters, respectively. We found 242 variable sites and 193 parsimony-informative sites in the ITS regions, whereas 172 variable sites and 104 parsimony-informative sites were found in the combined chloroplast regions. The GC ratios were 46.2 % and 37.4 % for the ITS and combined chloroplast regions, respectively. The phylogenetic tree (Fig. 5 ) revealed a topology similar to that obtained in a previous study ( Choi et al. 2020). The phylogenetic results showed some topological incongruence between the ITS and combined CP trees. In the ITS tree, the most basal clade (BS = 100 %) included the monophyletic C. grayanum and C. sinicum and showed a sister relationship with other Chrysosplenium species. However, the CP tree was divided into two clades, with C. grayanum and C. sinicum sharing the most common ancestors with the C. ser. Pilosa, C. kamtschaticum , and C. ramosum (BS = 94 %). The phylogenetic relationships among the three subclades were not fully resolved, and the C. ser. Pilosa. was not monophyletic, embedding C. kamtschaticum . Furthermore, the series Alternifolia was monophyletic in the CP tree but not in the ITS tree. Both trees strongly supported the monophyly of C. insularis (BS = 95 % in ITS, BS = 96 % in CP), and it shared the most common ancestor with C. alternifolium distributed in Japan (BS = 98 % in ITS, BS = 77 % in CP). The phylogenetic trees revealed that C. insularis formed an independent monophyletic clade from closely related taxa (i. e., C. japonicum and C. alternifolium ), suggesting the newly recognized species of Chrysosplenium (Fig. 5 ).

Additional specimens examined.

Chrysosplenium insularis (Paratypes): Korea • Jeonnam, Sinan-gun, Heuksan-myeon, Gageodo-ri ; 14 May 2023; K. H. Lee 230514-1 ( KH) . • Jeju, Seogwipo-si, Hogeun-dong ; 28 Apr. 2020; PBK 0118-001 ( KH) . • Jeju, Seogwipo-si, Hogeun-dong ; 22 Mar. 2022; Hanon-220322-011 ( KH) • Jeju, Seogwipo-si, Hogeun-dong ; 22 Mar. 2023; J. E. Jang et al. 230322-1 ( KH) .

Chrysosplenium japonicum : Korea • Gyeonggi, Gwangju-si, Chowol-eup, Mugap-ri , Mugapsan ; 24 Apr. 2007; HNHM-A- 158 • Gwangju-si, Toechon-myeon, Cheonjinam ; 7 Apr. 2000; KNAH 014041 • Gwangju-si, Toechon-myeon, Usan-ri , Aengjabong ; 11 Apr. 2004; kjs 040141 ( KH) • Incheon-si, Ongjin-gun, Jawoldo Isl. ; 8 Apr. 2009; NAPI- 2009-1214 ( KH) • Incheon-si, Ongjin-gun, Deokjeok-myeon , Mungap-ri , Gitdaebong ; 9 Apr. 2014; Park 140230 ( KH) • Incheon-si, Ganghwa-gun, Ganghwado Isl. ; 20 Apr. 2006; LeeGH 6-35 ( KH) • Gyeonggi, Namyangju-si, Onam-eup, Cheonmasan ; 17 Apr. 2009; ParkSH 90273 ( KH) • Gyeonggi, Namyangju-si, Onam-eup, Palhyeon-ri ; 25 May 2023; J. E. Jang 230325-1 ( KH) • Gyeonggi, Namyangju-si, Joan-myeon, Ungilsan ; 11 Apr. 2009; Y. M. Kang s. n. ( KH) • Gyeonggi, Gwacheon-si, Makgye-dong, Cheonggyesan ; 8 Apr. 2006; KHUS 20110475 ( KH) • Gangwon, Pyeongchang-gun, Yongpyeong-myeon, Jaesan-ri , Geumdangsan ; 17 Apr. 2012; JSY 120434 ( KH) • Jeongseon-gun, Imgye-myeon ; 23 Apr. 2011; 0307013 ( KH) • Gangwon, Taebaek-si, Hasami-dong, Deokhangsan ; 23 Apr. 2005; kjs 050052 ( KH) • Gangwon, Wonju-si, Panbu-myeon, Geumdae-ri ; 20 Apr. 2023; S. R. Lee et al. 230420-1 ( KH) • Chungbuk, Danyang-gun, Danyang-eup, Suchon-ri , Sobaeksan ; 17 Apr. 2005; Sobaeksan- 050417-070 ( KH) • Chungbuk, Chungju-si, Sotae-myeon, Boktan-ri ; 12 Apr. 2012; Namhan- 548 ( KH) • Gyeongbuk, Gunui-gun, Bugye-myeon, Dongsan-ri , Palgongsan ; 22 Apr. 2006; CBU- 070308 ( KH) • Gyeongbuk, Bonghwa-gun, Myeongho-myeon, Bugok-ri , Cheongnyangsan ; 27 Mar. 2006; CBU- 070519 ( KH) • Chungbuk, Cheongsong-gun, Hyeonseo-myeon, Bohyeonsan ; 22 Apr. 2006; K. O. Yoo s. n. ( KH) • Jeonbuk, Namwon-si, Ayeong-myeon, Gusang-ri , Bonghwasan ; 1 May 2007; HNHM-A- 283 ( KH).

Figures

Figure 1. Chrysosplenium insularis A habit B bulbils C stem D basal leaf E inflorescence, F bracteal leaves G flower H, I capsule J seed. Photographs by Ju Eun Jang and Kang-Hyup Lee.

Figure 2. Holotype of Chrysosplenium insularis.

Figure 3. Distribution map of Chrysosplenium insularis and C. japonicum in Korea (revised from Oh et al. 2016).

Figure 4. Comparative photographs of the habit (A, G), inflorescence (B, H), bracteal leaves (C, I), surface of bracteal leaves (D, J), and seed (E, F, K, L) of Chrysosplenium insularis (A – F) and C. japonicum (G – L). Photographs by Ju Eun Jang and Kang-Hyup Lee.

Figure 5. Phylogenetic tree of Chrysosplenium insularis and related taxa based on ITS regions and combined CP regions (mat K and rbc L) A ITS region B combined CP regions (mat K and rbc L). The numbers above the branches are bootstrap values (BS > 50 %) by the maximum likelyhood method. Newly generated sequences in this study are shown with an asterisk, and the new species are marked with a red box. The voucher information of all samples used in the analysis is indicated after the scientific names.