Hosta samukazemontana Se.Fujii & Yahara, 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

8. Hosta samukazemontana Se.Fujii & Yahara sp. nov.

Figs 19 , 20

Diagnosis.

Hosta samukazemontana is distinguished from H. polyneuronoides by anther size (3 mm vs. 3.5-4 mm), and inflorescences (deflected and curved upward at the top in contrast to erect and straight). Hosta samukazemontana is also similar to H. tosana in having inflorescences deflected and curved upward at the top, but distinguished from H. tosana by whitish perianths 4.5-5 cm long (in contrast to purple perianths 6.1-6.9 cm long) and whitish purple flower bracts 1.7-2.1 cm long (as opposed to whitish green peraiths 2.2-5.2 cm long).

Type.

Japan. Kochi Pref.: Tosa County, Hongawa Village, Mt. Kanpu , 25 Jul. 1983, Y. Kokami M83-255 with flowers (holotype MBK0175579!) .

Description.

Herbs perennial. Leaves basal, spiral, long petiolate, 2-6 per ramet; blades oblong-ovate, elliptic-ovate, ovate, 7-22 cm long, 3.6-10.7 cm wide, 1.8-2.9 time longer than wide, thinly papery, glabrous on both surfaces, base cuneate, rounded, cordate, decurrent, slightly folded, apex acuminate, margin entire, veins in 6-12 pairs, smooth on the lower surface; petioles 3.2-14.5 cm long, narrowly winged, wings 0.1-0.2 cm wide, glabrous. Scape 20-43 cm long, terete, deflected and curved upward at the top. Raceme 7-9 cm long, 5-18-flowered; flower bracts vivid (not withering) in anthesis, erect, whitish purple, oblong-lanceolate, boat-shaped, 1.7-2.1 long, 0.3-0.5 cm wide, membranous, glabrous, apex acuminate. Flowers 5-6 cm long; pedicels 1-1.8 cm long, glabrous. Perianths 4.5-5 cm long, purple-white outside, almost white inside, funnel-form, glabrous, 6-lobed, tube abruptly dilated from apical 2/3, lobes narrowly triangular, 1-1.3 cm long, 0.7-0.8 cm wide, apex acute, three veins distinct inside. Stamens 6; filaments 4.8 cm long, white, free, glabrous, almost as long as perianth, upwardly curved at the distal part, anthers purple when fresh, dark blue-grey when dried, 3 mm long. Ovary ellipsoid, 1 cm long, style 5 cm long, upwardly curved at the distal part, 0.5 cm exerted from perianth, glabrous, stigma capitate. Capsules green, cylindrical, 2.3-2.4 cm long, 0.4 cm wide, 3-angled. Seeds 2.2 mm long, with wings ca. 4 mm long, blackish brown.

Phenology.

Flowering in July, and fruiting in August.

Distribution and habitat.

Japan (Ehime and Kochi Prefectures) (endemic). This species grows on rock cliffs in the vicinity of Mt. Kanpu in the central part of the Kochi Prefecture on Shikoku Island.

Etymology.

The specific epithet was derived from the old name of the type locality (Mt. Samukaze).

Conservation status.

Using criterion D1 for IUCN Red List categories ( IUCN 2012, IUCN 2022), we recommend that this species be classified as VU (Vulnerable) because its population is estimated to be between 250 and 1000.

Japanese name.

Samukaze-giboshi (new).

Additional specimens examined.

Japan. Kochi Pref.: Agawa-gun, Ino-cho, along Kamegamori Forest Road , 1660 m elev., 22 Jun. 2021, T. Yahara et al. JPN6325 with flower buds (FU!) . Ehime Pref.: Saijyo City, W slope of Mt. Kanpu, 1050 m elev., 20 Aug. 2020, T. Yahara et al. JPN1380 - 1382 with fruit (FU!); Saijyo City, Mt. Kanpu 1600 m, 24 Jul. 2022, Se. Fujii JPN15235 with flowers (FU!); Mt. Kanpu , June 19, 1943, S. Yamawaki s.n. with flowers (TI!) .

Note.

This species was identified as H. shikokiana by Fujita (1976), but is distinguished from H. shikokiana in its whitish perianth color and scapes deflected and curved at the top when flowering and fruiting (Fig. 20 ). The distribution record of " H. kikutii var. caput-avis " from Mt. Kanpu in the Flora of Kochi Prefecture (Kochi Prefecture & Makino Memorial Foundation of Kochi Prefecture 2009) is a misidentification of this species.

Figures

Figure 19. The type specimen of H. samukazemontana: Y. Kokami M 83 - 255 (holotype MBK).

Figure 20. Plants of H. samukazemontana A JPN 1381 B JPN 6325 C photo taken on 17 Jul. 2013 by Y. Kokami; not collected. Scale bars: 10 cm (A, B); 2 cm (C).