Astilbe uljinensis B.U.Oh & H.J.Choi, 2020

Oh, Ami, Han, Sea-Hee & Oh, Byoung-Un, 2020, Astilbe uljinensis (Saxifragaceae), a new species from South Korea, PhytoKeys 161, pp. 89-98 : 89

Astilbe uljinensis B.U.Oh & H.J.Choi sp. nov. Figs 1 , 2

Diagnosis.

This new species is similar to A. chinensis , but differs from it due to the presence of a green young rachis of rhizomatous leaf, dense whitish long glandular hairs and sparse brownish long non-glandular hairs on the young rachis, dense brownish long glandular hairs of 1.5 to 2.7 mm length on the mature inflorescence, ovate-elliptic terminal leaflet, weakly undulated margin of leaf adaxial epidermal cell, and a stomatal apparatus of larger size and lower density on the leaf abaxial epidermis. These differences between A. uljinensis and A. chinensis have been summarized in Table 1 .

Type.

South Korea. Gyeongsangbuk-do: Uljin-gun, Sangdanggyo bridge, sunny or shady forest in mountainous area, 110m, 37°03'28.4"N, 129°17'41.6"E, 16 July 2015, B.U.Oh et al., 150716-1 (holotype: CBU!; isotype: CBU!) (Fig. 1 ).

Description.

Perennial, 57.4-125.7 cm tall. Roots fibrous, simple and stout, dark brown, 4.4-17.4 cm long, 0.2-0.4 mm in diam. Rhizomes extend, dark brown, 1.8-10.7 cm long, 12.6-26.8 mm in diam. Young shoots with dense long whitish glandular hair and sparse long brownish non-glandular hair on the surface, always green, 2.1-2.5 mm in diam. Rhizomatous leaves 2-3 ternate compound, 3-8 growing from rhizome, 31.5-68.5 cm long, 16.7-26.2 cm wide; terminal leaflet ovate to elliptic, apex acute to acuminate, base rounded or cuneate, margin double serrate, green; blade 52.2-81.3 mm long, 22.4-47.7 mm wide; rachis with dense long glandular hair. Bracts ternate leaf or 2-3 ternate compound, 0-2 growing from the rachis, usually smaller than rhizomatous leaves, 6.4-27.7 cm long, 3.6-13.7 cm wide. Inflorescence raches below bract erect, with dense glandular hair, green to reddish brown, 29.0-91.9 cm long, 2.3-4.7 mm in diam; those above bract developing panicle, 12.3-34.2 cm long, 0.8-2.2 mm in diam, with dense long brown glandular hair; peduncle, 32-40 from rachis, 2.2-7.4 cm long, 0.3-0.8 cm wide; pedicel 0.2-0.6 mm long. Flowers dense on peduncle, purplish red, 6.4-7.7 mm long, 1.4-2.2 mm wide; sepal 5, ovate, apex rounded, margin with short glandular hair, surface glabrous, white, 1.2-1.9 mm long, 0.8-1.0 mm wide; petal 5, linear, 1-veined, apex acute, 6.1-7.4 mm long, 0.2-0.3 mm wide; stamen 10, 3.2-3.9 mm long; filament linear, 2.8-3.4 mm long; anther ellipsoid, bright yellow to purple, 0.4-0.5 mm long; carpel 2, ovoid, surface glabrous, 2.0-2.3 mm long, 1.0-1.4 mm in diam. Fruits capsule, 2-parted, ovoid, green, surface glabrous, 3.3-3.8 mm long, 1.4-1.5 mm wide. Seeds numerous, irregularly ellipsoidal, dark brown, 1.0-1.4 mm long, 0.3-0.4 mm wide.

Distribution and habitat.

Currently, A. uljinensis is observed only in the central regions of South Korea, including Gangwon-do (Pyeongchang-gun, Samcheok-si, Gangneung-si) and Gyeongsangbuk-do (Uljin-gun). The species is found either in shady forests or on slopes near streams.

Phenology.

Flowering occurred between early June and late August. Fruiting occurred between July and October.

Conservation status.

At present, the known habitats of this new species are not being protected legally. In addition, since this species generally grows near streams, it is vulnerable to flooding. Previously, up to 10-20 individuals were found by the authors in some of this species’ populations. During the course of the present study, only a very small number of individuals were observed in some of the known habitats, probably indicating a decline in the plant population. However, the conservation status for the known populations has not been thoroughly investigated to date. Therefore, in accordance with the IUCN (2019) red list criteria, we suggest that this species should be treated as Data Deficient (DD).

Additional specimens examined.

South Korea. Gangwon-do: Pyeongchang-gun Odaesan, 4 July 1989, B.H.Choi, 4090 (KH!); Samcheok-si Deokhangsan, 16 July 2008, K.O.Yoo, 69542 (KWNU!); Samcheok-si Geombongsan, 18 July 2008, K.O.Yoo, 69544 (KWNU!); Samcheok-si Deokpung river, 11 July 2013, B.U.Oh et al., 130711-4 (CBU!); Samcheok-si Sagok-ri, 11 July 2013, S.H.Han & G.H.Kim, 130711-3 (CBU!); Gangneung-si Sogeumgang, 24 June 1988, C.M.Nam & H.C.Choi, 7056 (KWNU!). Gyeongsangbuk-do: Uljin-gun Sangdanggyo bridge, 11 July 2013, S.H.Han & G.H.Kim, 130711-1 (CBU!); Uljin-gun Deokgugyohoe stream, 11 July 2013, S.H.Han & G.H.Kim, 130711-2 (CBU!).

Figures

Figure 1. Holotype of Astilbe uljinensis B. U. Oh & H. J. Choi, B. U. Oh et al., 150716 - 1 (CBU).

Figure 2. Morphological characteristics of Astilbe uljinensis A habit B rhizome and root C base of rhizomatous leaf D secondary leaf axis E upper side of terminal leaflet F lower side of terminal leaflet G secondary rachis of inflorescence H flower I carpel J capsule K seed.