Hosta tardiva subsp. densinervia (N. Fujita & M.N. Tamura) Yahara & Se.Fujii, comb. &, 2023

Yahara, Tetsukazu, Hirota, Shun K., Fujii, Seiko, Kokami, Yasushi, Fuse, Kengo, Sato, Hiroyuki, Tagane, Shuichiro & Suyama, Yoshihisa, 2023, Molecular phylogeny and taxonomy of Hosta (Asparagaceae) on Shikoku Island, Japan, including five new species, one new subspecies, and two new status assignments, PhytoKeys 235, pp. 137-187 : 137

1B. Hosta tardiva subsp. densinervia (N. Fujita & M.N. Tamura) Yahara & Se.Fujii, comb. & stat. nov.

Fig. 8

Hosta kikutii var. densinervia N. Fujita & M. N. Tamura, Acta Phytotax. Geobot. 59: 34 (2008); Tamura & Fujita in Iwatsuki et al., Fl. Jap. IVb: 143 (2016). Type. JAPAN, Shikoku: Tokushima Pref, Miyoshi-gun, Ikeda-cho, Shikino-kami Ferry, 27 Sep. 1965, with flowers, S. Takafuji 253 (holotype KYO!, isotype KYO!).

Hosta kikutii var. polyneuron sensu Fujita, Acta Phytotax. Geobot. 27: 80. 1976, p.p.

Phenology.

Mid-August to September.

Distribution and habitat.

Japan (Ehime, Kagawa, Kochi, and Tokushima Prefectures). This subspecies is distributed in the lower reaches of the Yoshino River, the middle and lower reaches of the Niyodo River, the headwater of the Shinjyo River (near the headwaters of the Shimanto River), and the lower reaches of the Shimanto River (Fig. 7 ). It grows in open habitats on rocks and soil along the riverbanks.

Conservation status.

Using criterion D1 for IUCN Red List categories ( IUCN 2012, IUCN 2022), we recommend that this species be classified as LC (Least Concern) because its population is estimated to exceed 1000.

Japanese name.

Sudare-giboshi ( Maekawa 1952, excluding Yakushima-giboshi), Awa-giboshi ( Fujita and Tamura 2008).

Specimens examined.

Japan. Ehime Pref.: Kamiukena-gun, Omogokei, 13 Aug. 1970, N. Fujita 269, with flowers (KYO!); Saijyo City , 450 m elev., 6 Aug. 1971, H. Takahashi & N. Fujita 273 with young flower buds (KYO!); Nii-gun, 500 m elev., 30 Aug. 1955, G. Murata 9233 with flowers (KYO!) . Kagawa Pref.: Mt. Otaki , 24 Sep. 1961, S. Sakaguchi s.n. with flowers (KYO!) . Kochi Pref.: Agawa-gun, Niyodogawa-cho, Kuki , 80 m elev., 18 Aug. 2020, T. Yahara et al. JPN1255, 1258, 1263 with flowers (FU!); ditto, in the headwater of a tributary of Shinjyo River , 900 m elev., cultivated in Makino Botanical Garden, 8 Apr. 2021, T. Yahara et al. JPN3929 sterile (FU!); Agawa-gun, Ino-cho, Kashiki, 40 m elev., 20 Aug. 2020, T. Yahara et al. JPN1331 - 1333 with flowers (FU!); Takaoka-gun, Ochi-cho, Kataoka, 50 m elev., 20 Aug. 2020, T. Yahara et al. JPN1375 - 1377 with flowers (FU!); ditto, Tokoroyama, 13 Sep. 1962, G. Murata 17106 and 17107 with flowers (KYO!); Hata-gun, Nakamura-cho, along the Shimanto River , 20 Aug. 1913, Z. Tashiro s.n. with flowers (KYO!) . Tokushima Pref.: Miyoshi City, Shikino-kami, 90 m elev., 11 Apr. 2021, sterile, T. Yahara et al. JPN4071, 4072, and 4075 (FU!); Ikeda-cho, along the Yoshino River , 16 Sep. 1971, C. Abe 43049 with flowers (KYO!); Miyoshi-gun, Minawa-mura, Kawasaki, along the Iya River , 8 Sep. 1958, T. Yamanaka 26270 with flowers (KYO!) .

Note.

This subspecies is morphologically more similar to H. polyneuronoides , rather than to H. tardiva subsp. tardiva .

Figures

Figure 7. Maps of collection locations for Hosta species A Shikoku Island (black) in relation to Japan B detail of Shikoku Island with population locations for some species and varieties C details of collection locations for H. polyneuronoides (solid circles) and H. scabrinervia (an open square), and approximate ranges (circles) of H. minazukiflora (M), H. longipedicellata (L), H. samukazemontana (Sa), H. shikokiana (Sh), and H. takiminazukiflora (T). Considering conservation concerns, we refrained from disclosing the precise collection locations of these five species. The contour map was reproduced from a webpage. (https: // maps. gsi. go. jp / # 11 / 33.726624 / 133.351364 / & base = english & ls = english & disp = 1 & vs = c 1 g 1 j 0 h 0 k 0 l 0 u 0 t 0 z 0 r 0 s 0 m 0 f 1 & d = m) in accordance with the usage regulations of the Geospatial Information Authority of Japan.

Figure 8. Flowering plants of H. tardiva subsp. densinervia A JPN 1263,18 Aug. 2020 B JPN 1332, 20 Aug. 2020. Scale bars: 20 cm (A); 2 cm (B).