Allium dumebuchum H.J.Choi, 2021

Jang, Ju Eun, Park, Jong-Soo, Jung, Ji-Young, Kim, Dong-Kap, Yang, Sungyu & Choi, Hyeok Jae, 2021, Notes on Allium section Rhizirideum (Amaryllidaceae) in South Korea and northeastern China: with a new species from Ulleungdo Island, PhytoKeys 176, pp. 1-19 : 1

Allium dumebuchum H.J.Choi sp. nov. Figs 1A-E , 4

Diagnosis.

This new species is morphologically similar to A. senescens due to its habits. However, it is clearly distinguished from A. senescens , particularly by its rhomboid scapes in cross-secion (vs. subterete), light purple perianth color (vs. pale purple), entire and narrowly triangular inner filaments (vs. sometimes toothed and broadened for ca. 1/2 in length), and flowering season from late September (vs. from July).

Type.

South Korea. Gyeongbuk: Ulleung-gun, Namyang , 37.46702N 130.83665E, elev. 11m, 8 Oct 2020 [fl], H.J.Choi 201008-001 * (Holotype: KH; Isotypes: CWNU, KB, KIOM) .

Description.

Herbs hermaphroditic. Rhizomes clearly elongated, thick and branched, oblique to horizontal, 14.8-55.4 mm long. Bulbs clustered, cylindrically conical, 9.6-15 mm in diam.; tunics membranous, smooth, white. Leaves 4-9; sheaths slightly exposed above ground, 4-7.8 cm long; blades ascending, slightly tortuous, linear, flat and solid in cross-section, flesh, 19.5-38 cm × 3.8-13 mm, apex obtuse to rounded. Scapes rhomboid and solid in cross-section, drooping before flowering, 23.4-49 cm × 2.5-5.6 mm. Inflorescences umbellate, subglobose, 23-41.5 × 37-53 mm, 48-113 flowered; pedicels terete, subequal in length, 9.8-11.2mm long; bracts 3.2-5 mm long. Flowers bisexual; perianth semi-radially spreading, light purple; inner tepals longer than outer ones, elliptical, apex obtuse, 5.2-7.2 × 3.4-4.5 mm; outer tepals ovately elliptical, apex obtuse, 4.8-6.1 × 2.1-3.7 mm; filaments exserted, 6.2-8.4 mm long, margin entire; inner filaments narrowly triangular; anthers elliptical, reddish, 2.2-2.5 × 0.9-1.1 mm long; ovary obovoid, reddish, 3.2-3.8 × 3.2-3.7 mm, ovules 2 per locule; style terete, exserted; stigma smooth. Capsules cordiform, trigonous, 5.4-5.6 × 5.6-5.8 mm. Seeds oval, semi-circular in cross-section, 3.7-3.8 × 2.4-2.6 mm.

Phenology.

Flowering from late September to October; fruiting from late October to November.

Distribution and habitat.

Endemic to South Korea (Ulleung-do Island; Fig. 5 ). Open slope of rocky area.

Etymology.

The specific epithet, " Allium dumebuchum " is based on the name of traditional vegetable for this species in South Korea.

Vernacular name.

The Korean name of the new species is "Du-me-bu-chu ( 두메부추)”.

Conservation status.

The new species is endemic to Ulleungdo Island, and usually grows along the coast at altitudes of -23-171m a.s.l. From the present study, the extent of occurrence (EOO) and the area of occupancy (AOO) of this species have been calculated to be 47,683 km2 and 48 km2, respectively. Currently, there is no information on population size and trend data. However, this new species is only known from a single location of Ulleungdo Island, and mainly occurs on the coast which is critically threatened by extensive construction and repair of coastal roads ( Choi et al. 2012a). Therefore, decline in habitat area, habitat extent, and quality of habitat for this species have been continuously observed. Thus, Allium dumebuchum should be considered as Critically Endangered [CR B1ab(iii)] according to the IUCN Red List categories and criteria ( IUCN 2021).

Notes.

Allium dumebuchum , occurring in Ulleungdo Island of South Korea, has usually been misidentified as A. senescens ( Choi and Oh 2010; Choi and Oh 2011). However, this new species remarkably distinguished itself from its related species of section Allium senescens Rhizirideum (e.g., A. spirale , A. spurium , A. minus , and A. senescens ) in having clearly bigger floral parts that bloom from late September (Table 3 ; Fig. 1 ). The PCA results based on quantitative floral characters of five related species in section Allium senescens Rhizirideum clearly identified A. dumebuchum from others (Fig. 2 ). This new species is a tetraploid (2 n = 4 x = 32) taxon along with A. senescens , and A. minus is a diploid (2 n = 2 x = 16), whereas A. spirale and A. spurium showed polyploidy (Table 3 ; Fig. 3 ). Moreover, molecular phylogenetic analyses using chloroplast markers (ndhJ - trnF, trnH - psbA, psbD - trnT, and psbJ - petA) also clearly indicate that A. dumebuchum is genetically distinct from other species of section Allium dumebuchum Rhizirideum (Fig. 6 ).

Additional specimens examined

(Paratypes). South Korea. Gyeonggbuk: Ulleungdo Isl. , Namyang valley , 11 Sep. 2006, ParkSH 61820 (KH); Ulleungdo Isl. , Tonggumi, 26 Sep. 1995, S-4255 (KH); Ulleungdo Isl. , Namyang, 15 Aug. 2009, Ulleung68-090815-002 (KH); Ulleungdo Isl. , Namyang, 22 Aug. 2011, JMC12750 (KH); Ulleungdo Isl. , Namyang, 29 Oct. 2013, 2013KBV091 (KH); Ulleungdo Isl. , Namyang, 5 Sep. 2003, SCHONG2003100 (KH); Ulleungdo Isl. , Chusan, 2 Sep. 2009, JMC11306 (KH); Ulleungdo Isl. , Dodong, 18 Sep. 2007, H.J.Choi 070001 (KH); Ulleungdo Isl. , Sadong, 23 Aug. 2005, 1073 (KB); Ulleungdo Isl. , Sadong, 23 Aug. 2005, KH1283 (KB); Ulleungdo Isl. , Nari, 25 Sep. 2001, J.S.Kim s.n. (KB); Ulleungdo Isl. , Hyeonpo, 4 Oct. 2011, 19-1 (KB); Ulleungdo Isl. , Nari, 17 Sep. 2019, H.J.Choi 190917-01 (CWNU); Ulleungdo Isl. , Namyang, 8 Oct. 2020, H.J.Choi 201008-002 (CWNU); Ulleungdo Isl. , Namyang, 8 Oct. 2020, H.J.Choi 201008-003 (CWNU); Ulleungdo Isl. , Sadong, 12 Oct. 2005, NAPI-20101161 (KB); Ulleungdo Isl. , 11 Jul. 2013, H.J.Choi s.n. (KB); Ulleungdo Isl. , 23 Aug. 2005, 1406 (KB); Ulleungdo Isl., 3 Sep. 2008, SK2008-019-096 (KB); Ulleungdo Isl., 15 Oct. 2009, ksh84 (KB) .

Figures

Figure 1. Comparative photographs of the inflorescence, cross-section of leaf and scape, flower, and tepal and filament arrangement of Allium section Rhizirdeum in South Korea and northeastern China A-E A. dumebuchum (H. J. Choi 201008 - 001) F-J A. spirale (H. J. Choi 191010 - 01) K-O A. spurium (H. J. Choi 200831 - 01) P-T A. minus (H. J. Choi 080063) U-Y A. senescens (H. J. Choi 080119).

Figure 2. Principal components analysis plot of five Allium species of section Allium Rhizirideum in South Korea and northeastern China. dum = A. dumebuchum; min = A. minus; sen = A. senescens; spi = A. spirale; spu = A. spurium.

Figure 3. Mitotic metaphase chromosomes and their voucher plants of Allium species A A. dumebuchum (H. J. Choi 190917 - 01) B A. spirale (H. J. Choi 191010 - 01) C A. spirale (H. J. Choi 190910) D A. spurium (H. J. Choi 080390) E A. spurium (H. J. Choi s. n.) F A. senescens (H. J. Choi 080119, voucher plant: Fig. 2 of Choi and Oh 2010).

Figure 4. Allium dumebuchum A habit B inflorescence C underground structure (r = rhizome) D tepal and filament arrangement E Flower F pistil G capsule H seed. Photos by H. J. Choi: H. J. Choi 201008 - 001 (A, B, D-F) and H. J. Choi 070001 (C, G, H).

Figure 5. Distribution map of Allium dumebuchum and its related species section Allium dumebuchum Rhizirideum in Korea and northeastern China (revised from Sinitsyna et al. 2016).

Figure 6. Phylogenetic tree of Allium section Rhizirideum and related taxa based on concatenated alignments of four cpDNA regions (ndhJ - trnF, trnH - psbA, psbD - trnT, and psbJ - petA). The numbers above branches are bootstrap values (BS> 50 %) by maximum likelihood method. The samples of section Allium Rhizirideum and the new species are in blue and red blods, respectively. The accession numbers from Genbank were indicated after the scientific names.