A new species of Delphinium L. (Ranunculaceae) from Dagestan (Eastern Caucasus)

The new species Delphinium samurense Murtazaliev et Luferov (sect. Diedropetala Huth) is described from the Eastern Caucasus. The novelty is endemic to southern Dagestan (Rutul district). Its morphological differences from the closely related species D. macropogon Prokh. are shown. Distribution and ecology of the new species are characterized.


Delphinium samurense
Perennials, 70-120 cm high, with a tuberous nodose rhizome 2.5-4 × 1.5-2.5 cm and numerous branching thin adventitious roots (Fig. 1). Stems simple or slightly branched in the upper part, rounded and ribbed, with simple white very short (0.1-0.3 mm long) straight or arcuate, appressed or slightly deflected hairs; in the upper half of the shoot and especially in the inflorescence, with an admixture of yellowish (reddish) or white glandular trichomes 0.2-0.5 mm long, straight, protruding or subappressed, ovoid and broadened at the base and containing light yellow or colorless essential oil. Basal and lower stem leaves long-petiolate (petioles 10-22 cm long, 3-4 times exceeding leaf blade, flattened, grooved on the adaxial side, semiamplexicaul at the base, pubescent as stems). Blades of the basal leaves rounded-reniform or rounded-cordate, palmately dissected into 3-5(7) rhomboid segments on thin petiolules 3-8 mm long. Leaf segments of the first order dissected into up to 3-4 orders into numerous oblong-lanceolate or linear, entire or with single oblong-lanceolate teeth with acute or pointed tips, segments and lobes, glabrous above, with simple sparse scattered appressed hairs below, usually densely hairy at the margins; at the base of the leaf blades with a wide notch, stub or wedge-shaped. Upper leaves ovate-rhomboid, dissected into 3-5 segments, which, in turn, are dissected into narrowlanceolate and linear lobes of 2-3 orders. All leaves with strongly protruding veins on the lower surface, and more or less revolute margins of blades. Apical raceme multi-flowered (20-55 flowers), nar-row, compact (Fig. 2). Bracts entire, narrowly lanceolate, 8-15 × 0.8-3 mm, 1.5-2 times longer than the pedicels or equal to them. At the base of the inflorescence, the bracts twice or thrice trifid, 4-7 × 3-6 cm, 2-3 times longer than the pedicels. Two bracteoles attached close to each other, located 1-3 mm from the calyx, linear-subulate, entire, usually arcuate, 3-6 × 0.5-1.5(2) mm. Calyx white, often with yellowish and light green stripes on the bottom, after drying often (not always) turning blue, covered from the outside with simple, very short (0.2-0.4 mm long), appressed, arcuate and straight hairs. Spur straight or slightly arcuate, 14-17 mm long, 2-2.5(3) mm thick. ( fig. 3a), 2-3 times longer than the pedicels. Lateral sepals 10-14 × 4-7 mm, broadly cuneate at the base, acute or rounded at the tip ( fig. 3b). Lower sepals 10-14 × 2-4 mm, narrowly cuneate at the base, pointed at the top ( fig. 3c). Corolla blue, with blue, less often purple, longitudinally arranged veins. Petal nectaries 10-13 × 1.5-2 mm, narrow, pointed at the base and broadened to the bifid top with narrow acute lobes  . 4) and follicles 15-19 × 2.5-3 mm, with a slightly protruding dorsal vein, smooth on the sides, with appressed or subappressed short, 0.3-1 mm long, thin white hairs. Stylodia slightly arched, 4-6 × 0.3-0.6 mm. Seeds obovate or ellipsoidal, 0.7-1 × 0.6-0.8 mm, black; their surface is covered with small pressed scales.     Affinities. The species is closest to D. macropogon Prokh. (fig. 6), from which it differs well by a longer inflorescence, the colour and length of sepals, the length of the spur, the colour of nectar-ies and staminodes, the colour and length of hairs on staminodes, the length of follicles and stylodia (Table). Distribution. D. samurense is an endemic known only from southern Dagestan: Rutul district, the upper part of Samur River valley; the type of species range is South Dagestan. According to the botanical and geographical zoning of the Caucasus proposed by A. L. Takhtajan and Yu. L. Menitsky (Menitsky, 1991), this territory belongs to the Manas-Samur floral region situated in the southern part of Dagestan. It includes river basins of the Caspian Dagestan from Shura-Ozen River to Samur River. All locations of the species are situated in the upper part of the Samur River basin (fig. 7). The climate in the species habitat is continental with mild winters and summers. There are no accurate climatic data available for the habitat of the new species, but the average annual temperature in the nearby village of Luchek is known to be + 8 °С, and the average annual rainfall in the nearby village of Mishlesh is 749 mm (Gadzhieva, Solovyev, 1996). Here steppemeadows on low-density gristly soils on the southern slopes and mixed small-leaved forests and subalpine meadows on brown soils on the northern slopes are commonly found (Chilikina, Schiffers, 1962).
Delphinium samurense grows in sparse shrub communities on a rocky-gravelly slope with a welldeveloped grass cover. Plant communities, where this species occurs, include such herbs as  Tarki -Tau (Prokhanov, 1961;Murtazaliev, 2009Murtazaliev, , 2016Anatov, 2020). The type of the species range is northern Dagestan.
The origin of D. samurense, in our opinion, is autochthonous, which was previously noted for the majority of other species of this genus in the flora of the Caucasus (Kemularia-Natadze, 1966;Kemularia-Natadze, Gagnidze, 1969;Gagnidze, 1974). For this territory, 40 species of Delphinium were listed (Luferov, 2012), of which 24 are endemic, that also indicates their indigenous origin.
Attention must be paid to conservation of D. samurense populations. They consist of 5-10 to 50 individuals, of which generative individuals predominate. Plants are scattered: dense thickets are not formed. Seed propagation is noticed, but during dry years the germination rate is low (up to 10 %), as well as plant survival, especially in the first 3 years of ontogenesis. The population range is small (not more than 20-70 m²).
The limiting factors are livestock grazing, haymaking, grass burning; potentially -collecting flowering plants for bouquets due to their high ornamental value. In addition, the safety of populations is of concern, given its proximity to the highway and settlements.
The narrowly endemic nature of D. samurense, the peculiarities of the population structure of natural communities (predominance of generative individuals and a very small number of plants in the virginal period of ontogenesis), low seed productivity and exposure to limiting environmental factors call for the need of making efforts to protect natural populations of the new species and include it in the new edition of the Red Data Book of the Republic of Dagestan. Possibility of introducing D. samurense into cultivation should also be estimated.