An integrative taxonomic approach reveals a new species of Eranthis (Ranunculaceae) in North Asia Author Erst, Andrey S. Author Sukhorukov, Alexander P. Author Mitrenina, Elizaveta Yu. Author Skaptsov, Mikhail V. Author Kostikova, Vera A. Author Chernisheva, Olga A. Author Troshkina, Victoria Author Kushunina, Maria Author Krivenko, Denis A. Author Ikeda, Hiroshi Author Xiang, Kunli Author Wang, Wei text PhytoKeys 2020 140 75 100 http://dx.doi.org/10.3897/phytokeys.140.49048 journal article http://dx.doi.org/10.3897/phytokeys.140.49048 1314-2003-140-75 A0E57D4848DC5F8BB27FA5DBE34DEC61 Eranthis tanhoensis Erst sp. nov. Figs 5 , 6A-D , 7B Type. Russia, Republic of Buryatia, Kabansky district, Osinovka River near Tanhoi village, 51°33'06.2"N , 105°05'34.7"E , 458 m a.s.l., 01 May 2019, A.S. Erst , D.A. Krivenko , & O.A. Chernysheva s.n. (holotype, NS-0000948!, isotypes TK, IRK, E). Description. Herb perennial, 12.0-23.0 cm long at flowering and 18.0-40.0 cm long at fruiting. Tubers subglobose, not or slightly branching, 1.2-3.3 cm diam., producing thin fibrous roots. Basal leaf single, long-petiolate, green; petioles 5.0-6.0 cm long at flowering and 23-25 cm at fruiting; blades 2.5-3.8 x 2.5-3.5 cm at flowering and 7.5-12 x 7.5-12 cm at fruiting, deeply palmately divided into 5 segments (maximum length of segment dissection 2.3 cm at flowering (3.5 cm at fruiting)); leaf blade segments rounded or widely rhombic, 0.8-2.5 x 0.4-1.8 cm at flowering (1.7-8.5 x 1.2-7.5 cm at fruiting), unlobed or dissected into 1-2 lobes at both flowering and fruiting stages; segment of basal leaves with 5-19 acute teeth at apex at flowering, 6-25 teeth at fruiting. Involucre present, 1.1-5.5 cm diam. at flowering (7-11 cm at fruiting stage); involucral bracts (cauline leaf) sessile, laciniate, similar to basal leaf, divided into 5 trifid leaf-like segments (maximum length of segment dissection is 1.6 cm at flowering (4.0 cm at fruiting)); segments rounded or widely rhombic, 1.1-3.0 x 0.5-2.5 cm at flowering (3.3-6.4 x 1.4-5.3 cm at fruiting), unlobed or dissected into 2 lobes both at flowering and fruiting stages; each segment with 5-21 teeth (at both flowering and fruiting stages), acute at the apex. Pedicels 0.5-1.5 cm long, elongated in fruiting (3.5-5.5 cm long), densely covered with papillate and large hemispherical trichomes. Flowers bisexual, actinomorphic, solitary, erect, 2-4 cm diam. Sepals 4-7, deciduous in fruit, white or light pink at margin, flat, narrowly obovate or elliptic, 1.1-2.6 x 0.5-1.3 cm. Petals 5-15 x 0.6-0.8 cm long, bicoloured, white, tubular, two-lipped with bilobate or forked lips, each lobe of abaxial lip acute at the apex and with globular yellow swellings (nectaries: Fig. 7B ). Stamens 36-45, 0.7-1.1 cm long; filaments filiform, white; anthers white. Follicles 3-10, 0.8-1.4 cm long, on short (0.3-0.5 mm) stalks, divergent towards the end of fruiting; stylodium 0.1-0.3 mm long, straight or slightly curved. Notes. Turczaninow (1842) described the species E. uncinata Turcz., growing at higher altitudes and distinguished from E. sibirica by the number of petals (5-6, not strictly 5), by the shape of the stylodium (recurved rather than straight), smaller flowers and more dissected leaf blades. However, our studies have shown that these morphological characters are variable and all variations can be found both in the foothill and alpine plants. Shipchinskiy (1937) merged E. uncinata with E. sibirica . However, he described two varieties: E. sibirica DC. var. nuda Schipcz. with glabrous pedicels (= E. sibirica var. sibirica ) and E. sibirica DC. var. glandulosa Schipcz. with glandular-pubescent pedicels. These varieties were not validly published under ICN Article 39.1 ( Turland et al 2018 ). Nakai (1937) attributed E. sibirica and E. uncinata to the genus Schibateranthis Nakai (≡ Eranthis sect. Schibateranthis (Nakai) Tamura). Affinity. The new species belongs to E. sect. Shibateranthis (Nakai) Tamura and it is sister to E. sibirica , according to the results of molecular phylogenetic analysis (Fig. 1 ). E. tanhoensis is morphologically similar to E. sibirica and E. stellata (Figs 5 - 9 ) in having white sepals, tubular two-lipped petals with bilobate or forked lips, apically acute lobes with abaxial lip and globular yellow swellings (nectaries) at the top or in the central part. The differences amongst the three species are presented in Table 2 . Figure 5. General habit of Eranthis tanhoensis . Scale bar: 1 cm. Figure 6. Morphological differences amongst A-D Eranthis tanhoensis E-H Eranthis sibirica ; and I-L Eranthis stellata A, E, I flower position B, F, J flowers C, G, K involucral bracts and follicles D, H, L basal leaves. Figure 7. Petals. A Eranthis sibirica B Eranthis tanhoensis C Eranthis stellata . Figure 8. General habit of Eranthis sibirica . Scale bar: 1 cm. Figure 9. General habit of Eranthis stellata . Scale bar: 1 cm. Table 2. Morphological differences among E. sibirica , E. tanhoensis , and E. stellata .

Character	E. sibirica	E. tanhoensis	E. stellata
Leaf colour at flowering	green	green	coppery or green
Teeth at the apex of basal leaf segments	rounded	acute	rounded
Maximum dissection of the basal leaf segments (at flowering), cm	1.0	2.3	0.4-?
Maximum dissection of the basal leaf segments (at fruiting), cm	2.3	3.5	1.3
Number of teeth on the segments of the basal leaf (at fruiting)	3-12	6-25	3-5
Apex of involucral leaves	rounded	acute	rounded
Width of the involucral leaf segments (at fruiting), cm	0.4-1.2	1.4-5.3	0.5-2.3
Maximum dissection of the involucral leaf segments (at flowering), cm	1.6	1.6	1.0
Maximum dissection of the involucral leaf segments (at fruiting), cm	2.1	4.0	1.7
Number of teeth on the segments of the involucral leaf (at flowering)	1-5	5-21	3-9
Number of teeth on the segments of the involucral leaf (at fruiting)	2-5	5-21	3-8
Flower position	erect	erect	recurved
Scape pubescence	glabrous or with papillate trichomes	large hemispherical and papillate trichomes	glandular and stellate trichomes
Sepal number	5-7	4-7	5-8
Shape of petals	narrow urn-shaped	broadly urn-shaped	funnelform
Swellings (nectaries) position	at the apex	at the apex	in medium part
Apex colour of adaxial lip	yellow	yellow	white
Apex colour of abaxial lip	yellow	yellow	white
Margin colour between abaxial and adaxial lips	white	yellow	white
Stamen colour	white	white	violet, pink or white
Stylodium length, cm	0.2-0.5	0.1-0.3	0.2-0.4

The new species differs from other related species by dense glandular pubescence of the flower stems, rounded or widely rhombic (not obovate or lanceolate) leaf blade segments, acute, rather than rounded teeth apices of the basal and stem leaves, a large number of teeth and width of the segments of the basal and stem leaves (see also 2). Additionally, all three species growing in Russia have different distribution patterns (Figs 10 , 11 ). Figure 10. General distribution of Eranthis sibirica (dots) and E. tanhoensis (stars), based on herbarium materials. Figure 11. General distribution of Eranthis stellata , based on herbarium materials and data in the literature ( Oh and Oh 2019 ; Park et al. 2019 ). Phenology. Flowering time: April-early May; fruiting time: late May-June. Distribution (Fig. 10 ): Eranthis tanhoensis is endemic to southern Baikal (Khamar-Daban range of the Republic of Buryatia and Irkutsk Province). Habitat and ecology. Eranthis tanhoensis can be found at 350-2400 m a.s.l., where it grows in fir, Siberian pine, spruce and birch forests, on riverbanks, beside streams (up to 1500 m a.s.l.) and in subalpine meadows (at higher altitudes). Etymology. The specific epithet of the new species is derived from the type locality, Tanhoi village, Republic of Buryatia, Russia. Additional specimens examined. Russia: Republic of Buryatia: Kabansky district, Osinovka river (Tanhoi village), 51°33'06.2"N , 105°05'34.7"E , 458 m a.s.l., 20 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva s.n. (NS-0000949!); Kabansky district, Mishikha river, 51°37'46.7"N , 105°32'05.2"E , 480 m a.s.l., 01 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva 31 (NS-0000950!); Kabansky district, Mishikha river, 51°37'46.7"N , 105°32'05.2"E , 480 m a.s.l., 01 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva 31a (NS-0000951!); Kabansky district, Mishikha river, 51°37'32.6"N , 105°32'03.4"E , 478 m a.s.l., 20 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva s.n. (NS-0000952!); Kabansky district, Dulikha river, 51°32'04.9"N , 105°01'43.2"E , 461 m a.s.l., 01 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva 14 (NS-0000953!); Kabansky district, Dulikha river, 51°32'04.9"N , 105°01'43.2"E , 461 m a.s.l., 20 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva (NS-0000954!); Kabansky district, Shestipalikha river, 51°32'46.4"N , 105°04'28.9"E , 465 m a.s.l., 01 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva s.n. (NS-0000955!); Kabansky district, Shestipalikha river, 51°32'46.4"N , 105°04'28.9"E , 465 m a.s.l, 21 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva (NS-0000956!); Kabansky district, Tolbazikha river, 51°26'21.06"N , 104°41'09.82"E , 471 m a.s.l., 02 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva s.n. (NS-0000957!); Kabansky district, Tolbazikha river, 51°26'21.06"N , 104°41'09.82"E , 471 m a.s.l., 20 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva s.n. (NS-0000958!); Irkutsk Province: Slyudyansky district, Semirechka river, 51°28'56.92"N , 104°19'43.47"E , 470 m a.s.l., 02 May 2019, A.S. Erst , D.A. Krivenko & O.A. Chernysheva 048 (NS-0000959!); Slyudyansky district, Semirechka river, 51°28'56.92"N , 104°19'43.47"E , 470 m a.s.l., 21 Jun 2019, A.S. Erst , D.A. Krivenko , E.Yu. Mitrenina & O.A. Chernysheva s.n. (NS-0000960!). Preliminary conservation status. Although the species seems to have a small distribution area in southern Baikal Lake, the populations observed in 2018 and 2019 consisted of numerous individuals producing viable fruits and no threats to the habitats were observed in the field studies. The EOO of E. tanhoensis was estimated for an area of more than 1372 km2, while the AOO was 72 km2. Preliminary conservation status, according to IUCN's Extent of Occurrence criteria indicates the species as Endangered (EN) ( IUCN 2019 ).