145 Key words: Belene, Danube River, disjunct occurrence, Natura 2000, new record, wetland flora. Ključne besede: Belene, Donava, disjunktno pojavljanje, Natura 2000, novi podatki, mokriščna flora. Corresponding author: Georgi Kunev E-mail: gikunev@uni-sofia.bg Received: 3. 2. 2023 Accepted: 12. 1. 2024 Dipsacus gmelinii (Caprifoliaceae), a wetland species new to the Bulgarian flora Abstract Dipsacus gmelinii is here reported as a new addition to the vascular flora of Bulgaria. It was recorded on Belene Island, in the Danube River. In the present paper, the species is described morphologically with an emphasis on carpomorphological characters. The distinctive differences from related species of the genus are also highlighted. Additionally, ecological conditions and floristic composition at the localities of the species, and phytosociological relationships of the communities in which it participates are discussed. Izvleček V članku poročamo o vrsti Dipsacus gmelinii, ki je nova vrsta v flori Bolgarije. Našli smo jo na otoku Belene na Donavi. V članku smo opisali morfološke značilnosti vrste s poudarkom na karpomorfoloških znakih. Izpostavili smo tudi značilne razlike med sorodnimi vrstami znotraj rodu. Razpravljali smo o ekoloških razmerah in vrstni sestavi na rastiščih, kjer se vrsta pojavlja, in o rastlinskih združbah, v katerih smo vrsto našli. Georgi Kunev1, Ivan Kostadinov2 & Daniela Karakasheva3 1 Sofia University “St. Kliment Ohridski”, Faculty of Biology, Department of Botany, Sofia, Bulgaria 2 Sliven, Bulgaria 3 Pesrsina Nature Park Directorate, Belene, Bulgaria DOI: 10.2478/hacq-2023-000723/1 • 2024, 145–150 23/1 • 2024, 145–150 146 Kunev et al. Dipsacus gmelinii new species to the Bulgarian flora Introduction Belene (Persin) is the largest Bulgarian island in the Dan- ube River. It falls within the borders of Persina Nature Park, it is a Ramsar site, and part of Natura 2000 protected site BG0000396 Persina (MoEW, 2016). There are three big wetlands on the Island covering more than 2000 ha. They were completely drained in the beginning of last cen- tury because of riverbank reinforcement. In 2008 connec- tion of the wetlands with Danube River was restored under Lower Danube Green Corridor Initiative by implementing Wetlands Restoration and Pollution Reduction project, fi- nanced by Global Environmental Facility (GEF). From then on, the water level in the wetland is managed by Persi- na Nature Park Directorate, which allows regular flooding of the wetlands. After the restoration of the water regime, the wetland ecosystem started slowly to recover, bringing back typical wetland species like Dalmatian pelican (Pele- canus crispus) and other bird species (Cheshmedziev et al., 2022), as well as typical wetland flora. During botanical trip carried out in the summer of 2022, in the Belene Island, the second and the third authors came across to an unknown representative of the genus Dipsacus (Caprifoliaceae). The plants were initially identified by the first author as D. gmelinii M. Bieb., based on examination of detailed photographs. Latter, in the same vegetation sea- son a second field trip to the same site was held in order to insure plant material for reliable identification and prepar- ing herbarium vouchers. Further on, following thorough examination of the collected plant specimens and consult- ing relevant literature, the initially proposed identity was confirmed. Therefore, our aim is to report the first finding of D. gmelinii in Bulgaria. The main distinguishing char- acteristics that facilitate the identification of the species are presented, as well as ecological peculiarities of the habitat. In conclusion, some initial measures for protection of its single population in Bulgaria are proposed. Methods and Methods Collected specimens were identified according to Hansen (1976). The identification was verified by examination of exsiccates through the virtual herbarium of the Moscow State University (MW) (Seregin, 2023). Dried materials were vouchered in Herbaria of Sofia University (SO) and Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences (SOM) (herbarium acro- nyms follow Thiers, (2023)). Diagnostic characters were noted from our own gatherings. Mature achenes were fur- ther collected and illustrated through photographs creat- ed by focus stacking technic. Ecological characterististics were recorded at the field. Results and discussion Dipsacus gmelinii M. Bieb. Fl. Taur.-Caucas. 1: 92. 1808 (Figure 1) Plants biennial. Stems 150–180 cm tall, usually multi- branched, upper portion distinctively ridged, with slender prickles along ridges. Rosulate leaves petiolate, spathu- late-lanceolate; cauline leaves opposite, sessile or subses- sile, lanceolate, lower serrate, upper laciniate, segments lanceolate-linear. Inflorescences corymbose, composed of 8–30 capitula. Capitula subglobose in pre-flowering stag- es, ovoid during anthesis, 2–5 cm long. Involucral bracts linear, spreading or slightly curved upwards, margins spi- nulose, apex acuminate, 10–30 x 1.2–2.5 mm. Bracteoles monomorphic, 8–12 mm long, proximal end obovoid, membranous, 4–7 x 2.5–3.5 mm, gradually tapering into 4–7 mm long awn. Corolla tube whitish, throat and limbs bluish-lilac, 5–6 mm long. Achenes 4-angled in cross-section, longitudinally ribbed, 5–6.5 mm long (see also Carpomorphological examination subchapter). Examined specimens Dipsacus gmelinii: 1) Bulgaria: Persin island, damp place along abandoned drainage channel, 20 m alt., 43.6625°N, 25.2424°E, coll. date: 01 Aug 2022, leg.: Daniela Kara- kasheva, det.: Georgi Kunev (SO 108216; SOM 177779); 2) Bulgaria: Persin island, 43.6613°N, 25.2419°E, Dan- iela Karakasheva & Ivan Kostadnov (01 Aug 2022, pers. obs.); 3) Russia: Astrakhan Province, Kamyzyakskii region, – 20 m alt., 46.1454°N, 48.2589°E, coll. date: 10 Aug 1951, leg. & det.: Proskuryakova & Vostokova (MW0525513, photo); 4) Kazakhstan: coll. date: 9 Aug 1957, leg.: E. Zolotarev (MW0880641, photo); D. lacini- atus: Bulgaria: Sofia, ruderal site near the Central rail- way station, 42.7162°N, 23.3182°E, G. Kunev (05 Aug 2022, fruit sample); D. fullonum: Bulgaria: Sofia, ru- deral site near the Central railway station, 42.7162°N, 23.3182°E, G. Kunev (05 Aug 2022, fruit sample). Dipsacus gmelinii is reported to Bulgarian flora for the first time. Morphological features of the Bulgarian speci- mens were in congruence with the previously published descriptions of this taxon (Marschall von Bieberstein, 1808; Kotov, 1961; Bobrov, 1972; Hansen, 1976) and with the additions of Andrei (1968). According to most recent treatment of the genus Dipsacus for the Bulgarian flora (Petrova, 2013), three taxa have been so far known as native to the country: D. pilosus L., D. laciniatus L., and D. fullonum L. The new addition, D. gmelinii is morphologically well-separated from the above men- tioned taxa by combination of characters as upper leaves not or only slightly connate at base, involucral bracts 23/1 • 2024, 145–150 147 Kunev et al. Dipsacus gmelinii new species to the Bulgarian flora shorter than capitula, and short bluish-lilac flowers. The identification of D. gmelinii at the field may be quite straightforward if mature individuals are available. It is most similar to D. fullonum but it differs from the latter by several conspicuous traits (Table 1). Carpomorphological examination The achenes of D. laciniatus, D. fullonum and D. gmelinii include some common features as rectangular-prismatic shape, sides longitudinally ribbed, covered with minute adpressed bristly hairs, bearing membranous coroniform appendage (corona) at apical end. However, their dif- ferences are more pronounced and could be useful for identification at the field, especially late in the vegetation season when leaves and flowers are completely withered. We performed carpomorphological study that showed the achenes of D. fullonum (Figure 2A) were 3–4 mm in length, light brown, with three primary ribs, each paired with two slender secondary ribs, fissures narrower than in D. laciniatus; corona 0.1–0.2 mm, arcuate, papillate. The achenes of D. gmelinii (Figure 2B) were 5–6.5 mm in length, straw colored, ribs broad, fissures narrow, median rib narrow than lateral; corona 1.4–1.8 mm, somewhat membranous, ribs tapering through corona sides as broad branched veins, ending in gradually diminishing from an- gles to center of achene side spines. The examined achenes of D. laciniatus (Figure 2C) were 3.5–4.5 mm in length, dark brown, with three narrow ribs and broad fissures; corona 0.2–0.3 mm, truncate, ciliate, margins irregularly denticulate or lacerate. Phytosociological notes Dipsacus gmelinii has been observed in two microsites (Figure 3) with overall 20 individuals. The plants partici- pated in plant communities developed in wet depressions along drainage channel. The vegetation at the localities Table 1: Comparative characteristics of D. gmelinii and D. ful- lonum based on specimens from wild Bulgarian populations. Tabela 1: Primerjava znakov vrst D. gmelinii in D. fullonum na osnovi primerkov iz naravnih populacij v Bolgariji. Character D. gmelinii D. fullonum Leaves lower cauline leaves sessile, usually free at base, upper cauline leaves laciniate lower cauline leaves conate, upper cauline leaves usually entire Leaf margin serrate-laciniate crenate-dentate, occasionally irregu- larly prickly-dentate or entire Stem lower portion of stem not or weakly ridged, covered with soft pat- ent bristly spines lower portion of stem more or less ridged, covered with stiff curved prickles along ridges Capitula subglobose to ovoid, 2–5 cm in length ovoid-cylindrical, 4–8 cm in length Involucral bracts normally spreading, similar in length, shorter than capitulum recurved upwards, very unequal in length, the longest up to 3 times longer than capitulum Flower bracts more or less uniform, 8–12 mm in length dimorphic, lower 15–18 mm, apical 25–30 mm in length Flower length 5–6 mm 9–11 mm Figure 1: Morphological characteristics of Dipsacus gmelinii: A) General appearance and habitat; B) Upper stem portion; C) Leaf margin; D) Lower stem portion with soft patent bristly spines; E) Dried specimen deposited at SO (108216). Photos: I. Kostadinov. Slika 1: Morfološke značilnosti vrste Dipsacus gmelinii: A) splošen izgled in rastišče; B) zgornji del stebla; C) rob lista; D) spodnji del stebla z mehkimi, svetlečimi, ščetinastimi bodicami; E) posušen primerek, shranjen v herbariju SO (108216). Fotografije: I. Kostadinov. A B C D E 23/1 • 2024, 145–150 148 Kunev et al. Dipsacus gmelinii new species to the Bulgarian flora were composed of mostly mesophilous and hygrophilous species, typically tall herbs and reeds as Lythrum salicaria L., Chaiturus marrubiastrum (L.) Ehrh. ex Rchb., Lysi- machia vulgaris L., Glycyrrhiza echinata L., Stachys palus- tris L., Thalictrum flavum L., Carex cf. buekii, Euphorbia lucida Waldst. & Kit., Phalaris arundinacea L., Sonchus arvensis subsp. uliginosus (M.Bieb.) Nyman, Bidens sp., Chenopodium ficifolium Sm., Echinocystis lobata (Michx.) Torr. & A.Gray, Xanthium orientale subsp. italicum (Moretti) Greuter, Typha latifolia L., Allium angulosum L., Salix alba L., and Amorpha fruticosa L. At present, we could not identify the phytosociologi- cal affinities of D. gmelinii. The vegetation at the locali- ties is complex and composed of species characteristic for various high-ranked syntaxa. According to Golub et al. (2015), D. gmelinii is a diagnostic taxon for the associa- tion Calystegio-Phragmitetum Golub et Mirkin 1986 of the alliance Phragmition communis Koch 1926 and the class Phragmito-Magnocaricetea Klika in Klika et Novák 1941 described from the lower Volga Valley, SE Russia. At Belene Island the species shows similar affinities. The species pool was influenced by surrounding vegetation, generally reed communities dominated by Typha sp. and Phragmites australis (Cav.) Steud. and stands of the associ- ation Amorpho–Salicetum albae Tzonev 2009 nom. prov. of the class Salicetea purpureae Moor 1958 (Tzonev, 2009; MoEW, 2016). However, due to the hydrological regime of seasonal floods, the vegetation at the sites of D. gmelinii was ad- ditionally influenced by taxa characteristic for tall herb fringe communities; for example, such are some taxa of the alliance Veronico longifoliae–Lysimachion vulgaris (Passarge 1977) Balatová-Tulačková 1981 of the class Figure 3: Distribution map of Dipsacus gmelinii in Bulgaria. Yellow dots showing the two microsites observed on Belene Island in 2022. Slika 3: Karta razširjenosti vrste Dipsacus gmelinii v Bolgariji. Rumeni točki prikazujeta lokaciji mikrorastišč, ki smo ju zabelelžili na otoku leta 2022. Figure 2: Carpomorphological comparison of achenes: A) Dipsacus fullonum; B) D. gmelinii and C) D. laciniatus. Photo: I. Kostadinov. Slika 2: Primerjava karpomorfoloških znakov rožk: A) Dipsacus ful- lonum; B) D. gmelinii and C) D. laciniatus. Photo: I. Kostadinov. 23/1 • 2024, 145–150 149 Kunev et al. Dipsacus gmelinii new species to the Bulgarian flora Molinio–Arrhenatheretea Tuxen 1937 already reported from the same region (see Tzonev, 2009). Geographic range The geographic distribution of D. gmelinii includes Eastern Europe and Western Asia: Romania, Ukraine, Eastern Russia, Northern Caucasus, Western Siberia, Ka- zakhstan, and Altay (POWO, 2023). According to our knowledge, its closest occurrence lies near Jijila, Tulcea County, Northern Dobrudzha, Romania (Andrei, 1968). It has been known also from the Danube Delta Biosphere Reserve (Doroftei et al., 2011). We assume that D. gmelinii is recently introduced to Belene Island since the flora and vegetation of the island has been extensively studied in the last 20 years and this particular location was visited repeatedly for monitoring of the critically endangered in Bulgaria Allium angulosum (Tzonev, 2009, 2015; MoEW, 2016). However, up to now, only D. laciniatus has been registered at the studied area. D. gmelinii inhabits damp shores of lakes and rivers and moist depressions across its range (Bobrov, 1972; Hansen, 1976). The species produce abundant number of seeds that fall mostly close to the parent plants and has great expansion potential (Andrei, 1968), in the same way as D. laciniatus and D. fullonum. The latter two species are dispersed mostly through anthropochory, including outside their native range (Daddario et al., 2017). How- ever, D. gmelinii is more restricted globally and has nar- row habitat range, so its dispersal strategy is most prob- ably different. Belene Island, as an important bird area, is connected with the Danube Delta through migratory pathways of many waterfowl birds. Therefore, we assume that most probable way of introduction of D. gmelinii to the Belene Island is through migratory waterfowl, simi- larly to many wetland plant species inhabiting temporary flooded habitats (Salisbury, 1970; Deil, 2005). The finding of D. gmelinii on the island of Belene is interesting and significant from biogeographical point of view because it is the westernmost disjunct occurrence of the species within its global range. In Romania, it was evaluated as Vulnerable (Dihoru & Negrean, 2009) and it is possible to show same trait also in Bulgaria. Due to its single locality in the country and relatively distant (approximately 300 km in NE) neighboring populations of the species in Romania, we assume there is a high ex- tinction risk for of its Bulgarian population. Therefore, some measures should be taken in this regard as regular monitoring of its population, search for new localities in available suitable habitats, and control of some aggressive competitors as Amorpha fruticosa, Phragmites australis and Phalaris arundinacea at the known localities. Acknowledgements We are grateful to Chavdar Gussev from the Institute of Biodiversity and Ecosystem Research at the Bulgarian Academy of Sciences and Rosen Tzonev from Sofia Uni- versity for providing some of the references cited here. Georgi Kunev  https://orcid.org/0000-0002-3172-8518 References Andrei, M. (1968). Dipsacus gmelini M.B., specie nouă pentru flora României. Studii si cercetari de Biologie, Seria Botanica, 20(2), 107–111. Bobrov, E. G. (1972). Dipsacus L. In B. K. Shishkin & E. G. Bobrov (Eds.), Flora of the U.S.S.R. 24 (pp. 16–20). Israel Program for Scientific Translations. 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