Viola orientalis (Violaceae) – a new species for the flora of Sakhalin Island (Russian Far East)

Толық мәтін

In May 2022, conducting a survey of the flora of the southwestern coast of Sakhalin Island, we found a population of unusual yellow-flowered violet, which has been identified as Viola orientalis subsp. orientalis. Before our finding, this species had been known only in the extreme south of the Russian Far East (Primorye and the south of Khabarovsk Territory) without any reports for the Sakhalin region (Sugawara, 1939; Vorob’ev et al., 1974; Barkalov, Taran, 2004).

In May 2023, we conducted a re-survey of the location of the species in order to study the population size, ecological and cenotic conditions and the area where the species grows. Below is the data we received. Specimens are stored in the herbarium of the IMGG FEB RAS (SAK); doublets were transferred to the herbarium of the V. L. Komarov’s Botanical Institute RAS (LE) (http://rr.herbariumle.ru/01272542). Photos of living plants in their natural habitat have been uploaded to Inaturalist.org (iNat 196076079). The names of vascular plants are given according World Flora Online (www.worldfloraonline.org).

Viola orientalis (Maxim.) W. Becker subsp. orientalis: Nevelsky district, coast of the Tatar Strait, 5 km north of Shebunino village, mouth of the nameless stream (46°28ʹ26.0ʺ N, 141°49ʹ48.0ʺ E), a mixed-grass meadow on the slope of a stream, 20 V 2023. T. I. Koroteeva.

The habitat of the species is the valley of a small stream. The low part of stream slopes is covered with an emerging tall grass-sedge community of Filipendula camtschatica (Pall.) Maxim., Petasites japonicus subsp. giganteus (F. Schmidt ex Trautv.) Kitam., Polygonatum odoratum var. maximowiczii (F. Schmidt) Koidz. and Carex spp. However, violets grow en masse on forb-grass slopes, on which species of the family Poaceae dominate. There also Maianthemum dilatatum (Alph. Wood) A. Nelson et J. F. Macbr., Bupleurum longiradiatum Turcz., Ranunculus franchetii H. Boissieu, Rhodiola rosea L., Hemerocallis middendorfii Trautv. et C. A. Mey., Aruncus dioicus (Walter) Fernald, Saussurea acuminata subsp. sachalinensis (F. Schmidt) Kitam., Arnica sachalinensis A. Gray, Artemisia sp. are in grass cover. On the collection date (May 20) V. orientalis was blooming en masse. A thorough examination of the stream bed at a distance of 1 km from mouth showed that the population is located on both slopes of the stream 140 m from its mouth at a distance of about 150 m and numbers 300–400 individuals.

In Russia, Viola orientalis is represented by two subspecies: V. orientalis subsp. orientalis (= V. conferta (W. Becker) Nakai), that was previously known only in the south of the Far East – in Primorye and in the south of the Khabarovsk Territory and V. orientalis subsp. xanthopetala (Nakai) Espeut, distributed in the south of Primorye, and outside the Russian Federation – in northern China, Korea and on the Japanese islands of Honshu and Kyushu (Espeut, 2020). The species grows on dry and rocky slopes covered with forest, in mixed forests, in mountain woodlands, at the edge of forests, in thickets of bushes and on grassy mountain slopes, at an altitude of 100 to 1100 m (Bezdeleva, 1987). On Sakhalin Island V. orientalis is on the northeastern border of its range.

The characteristic features of the species in comparison with other yellow-petaled violets of Sakhalin and the Kuril Islands are: corolla completely bright yellow-colored; lateral petals bearded; apical part of the style capitate and bearded; rhizome short and erect. It is distinguished from the V. orientalis subsp. xanthopetala by cauline leaves all subsessile and pubescent capsules (fig. 1).

In total, 6 species of violets with partially or completely yellow-colored flowers are known on Sakhalin and the Kuril Islands. In addition to V. orientalis, these are V. arvensis Murray, V. biflora L., V. brevistipulata W. Becker, V. crassa Makino and V. kitamiana Nakai (= V. bezdelevae Vorosch.). Of these, V. biflora is quite common, which is found throughout Sakhalin, except for the southwestern, northeastern and northwestern floristic district, and on all more or less large islands of the Kuril ridge, as a rule, in the valleys of streams along their banks and slopes. V. crassa, similar to it, which characterized by shorter plant height and dense thick leaves with a wide notch at the apex, is known on Sakhalin only in the East Sakhalin mountain district (Sugawara, 1939; Vyshin, Barkalov, 1990; Katalog…, 1999) and on the Schmidta Peninsula (Sabirova, Sabirov, 2011), where it is found exclusively on rocky placers in the mountains or gravelly slopes along the sea coast. There is also an indication of the growth of V. crassa on the Moneron Island near the southwestern coast of Sakhalin, but these indications need to be verified (Katalog…, 1999; Barkalov et al., 2006). In the Kuril Islands, this species is much more widespread, where, like V. biflora, it is found on all more or less large islands, but grows in forb coastal meadows and subalpine lawns, on gravelly placers and slag fields in the mountains (Barkalov, 2009).

Viola brevistipulata and V. kitamiana are extremely rare and are only in the Kuril Islands. The first of them is indicated for the Southern Kuriles (Akiyama et al., 1999), the second – for the highlands of the Stokap Volcano on Iturup Island (Bezdeleva et al., 2006 – as V. bezdelevae; Barkalov, 2009). A characteristic feature of this violet is white flowers with a yellow center and dark veins (Espeut, 2020). In addition, apparently, the observation of a vegetating violet made by Dmitry Kulakov at the top of the Baransky volcano (Iturup Island) belongs to this species (Inaturalist.org – iNat 35487056).

Fig. 1. Viola orientalis subsp. orientalis (Sakhalin Island, Nevelskiy District, May 20, 2023).

Another violet that has white flowers with a yellow center, but branching shoots and leaf-shaped stipules is V. arvensis, which is introduced to Sakhalin. It is found as a weed in agricultural fields in the Tymovsky district and the vicinities of Yuzhno-Sakhalinsk (Katalog…, 1999).

Other yellow-flowered violets are also known in the Russian Far East – V. uniflora L., V. muehldorfii Kiss, V. kusnezowiana W. Becker. The probability of finding the last two on Sakhalin and the Kuril Islands is quite high. Therefore, below we provide a key for identifying all yellow-flowered violets of the Russian Far East. This key is based on the revision of the genus Viola in the Russian Far East (Espeut, 2020).

1 Throat of spurred petal pilose; stipules dentate, lobed or divided subg. Melanium: V. arvensis

1 Throat of spurred petal glabrous or shortly papillose; stipules undivided or at most toothed

2 subg. Chamaemelanium

2 Corollas white with yellow center sect. Kitamianae: V. kitamiana

2 Corollas completely yellow 3

3 Plants without annual erect or decumbent stems; rhizome long creeping, slender, whitish, producing directly flowers and leaves; style tubular

sect. Memorabiles: V. kusnezowiana

3 Plants with annual erect or decumbent stems producing flowers; style 2-lobed or capitate 4

4 Leaves emarginate, obtuse or subobtuse; lateral petals beardless; apical part of the style 2-lobed and beardless 5: sect. Dischidium

4 Leaves with ± extended acute apex; lateral petals bearded; apical part of the style capitate, bearded on the both sides 7: sect. Chamaemelanium

5 Leaves thin, soft, matt, with marginal teeth ended by an inconspicuous gland; capsule up to 6 mm long; lower petal up to 13 mm long, apex acute to obtuse, never truncated; sepals green; 2n = 24 V. biflora

5 Leaves thick, firm, glossy or matt, with marginal teeth ended by a conspicuous gland; capsule up to 8 mm long; lower petal up to 15 mm long, apex usually rounded or truncate, sometimes obtuse, never acute; sepals often tinged with purple-red; 2n = 48

6: V. crassa

6 Leaves distinctly pubescent above, more slightly beneath V. crassa subsp. avatchensis

6 Leaves glabrous on both sides

Vcrassa subsp. borealis

7 Lowest cauline leaf with a flower at its axil 8

7 Lowest cauline leaf without a flower 10

8 Rhizome short, erect; sepal appendages little but distinct 9: V. orientalis

8 Rhizome long, creeping, branched; sepal appendages inconspicuous V. brevistipulata

9 Cauline leaves 2(3), subsessile; capsules pubescent

 Vorientalis subsp. orientalis

9 Cauline leaves generally 3, the lowest one distinctly petiolate; capsules glabrous

 Vorientalis subsp. xanthopetala

10 Lowest cauline leaf distinctly petiolate, distant from the upper ones that are grouped in the upper part of the stem; rhizome long, slender, procumbent

 Vmuehldorfii

10 Lowest cauline leaf shortly petiolate, close to the upper ones in the upper part of the stem; rhizome vertical or oblique V. uniflora

Acknowledgements

We thanks Dr. V.Yu. Barkalov (Federal Scientific Center of the Far East Asia Terrestrial Biodiversity FEB RAS, Vladivostok) for identification of Ranunculus franchetii. Tatjana Koroteeva thanks Igor Koroteev and Vladimir Kaganov for their assistance in organizing field research in southwestern Sakhalin. The work of Tatjana Koroteeva was carried out within the framework of the state task, according to the thematic plan of the IMGG FEB RAS (AAAA-A18-118012290122-1).

Авторлар туралы

T. Koroteeva

Хат алмасуға жауапты Автор.
Email: tatjana_05@mail.ru
Ресей, Nauki str. 1B, Yuzhno-Sakhalinsk, 693022

M. Espeut

Email: marc.espeut@free.fr
Ресей, Nauki str. 1B, Yuzhno-Sakhalinsk, 693022

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2. Fig. 1. Viola orientalis subsp. orientalis (Sakhalin Island, Nevelskiy District, May 20, 2023).

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