Astragalus bartinense (Fabaceae), a new species from Turkey

Introduction

The genus Astragalus L. (Fabaceae) is represented by 2,398 taxa in the Old World, which are classified into 10 subgenera and 136 sections (Maassoumi 1998,Podlech and Zarre 2013). In Turkey, the genus is represented by 476 taxa in 63 sections with 51% endemism (Maassoumi 1998,Aytaç 2000, Aytaç et al.2012,Ekici et al. 2015, Dönmez andAydin 2018).

In the Old World 86 taxa are annual within 21 sections, and 2297 taxa within 115 sections are perennial, 97 sections are simple and 39 sections are bifurcate or bifid hairy (Podlech and Zarre 2013). In Turkey, 18 taxa are annual within 9 sections and 458 taxa perennial within 54 sections; 34 sections are simple hairy and 29 sections medifixed or bifid hairy (Aytaç et al. 2012).

Astragalus is the biggest genus in the world in terms of number of species and is dominant in the steppes, in Central Asia, Iran (Ghahremaninejad 2015) and Turkey (Irano-Turanian Region), which are suggested to be centers of diversification of the genus (Maassoumi 1998). Recently, the morphologically based classification of the genus has been shown to be artificial and does not correspond with the phylogenetically recovered clades (Azani et al. 2017,2019).

The section Tapinodes is represented by three species in the Old World, A. depressus, A. tetuanensis and A. froedinii (Podlech and Zarre 2013).

The specimen collected from Bartın was compared with A. depressus and A. froedinii (sect. Tapinodes) and we decided to describe it as a new species.

Materials and methods

Flowering and fruiting materials of the new species were collected in June 2016 at an elevation of 550 m in limestone rocky areas above Abdurrahman village in the Küre Mountains National Park in Ulus County, Bartın Province. The location of the new species in Bartın Province falls within the A4 grid square (Davis 1965).

The types and images for Astragalus depressus, A. froedinii and A. tetuanensis were examined from different herbaria, such as E, K, M, MSB, P, RAB and W. On the other hand, many specimens of A. depressus were investigated in the ANK, GAZI and HUB herbaria.

Pollen slides were prepared using the technique ofWodehouse (1935). Light microscope (LM) studies were made using a Leica ICC50 HD microscope. Measurements were based on 30 or more pollen grains for A. bartinense and A. depressus. For scanning electron microscope (SEM), dry pollen grains were mounted on stubs and coated with gold. Morphological observations were made with a JSM 6060 electron microscope. The terminology used is mainly that ofFaegri and Iversen (1992), andPunt et al. (2007). The pollen shape class based on the polar axis to equatorial axis (P/E) was identified using Erdtman’s system (1969).

Research materials were collected during the flowering and fruiting periods.

Macromorphological observations of the seeds were carried out using a stereoscope microscope. Axis parameters were measured with the aid of an ocular micrometer. For SEM, dry seeds were directly mounted on stubs using double-sided adhesive tape.

The leaflets were investigated with the same methodology as the seeds using a stereo microscope and SEM.

The SEM photomicrographs were taken with the JEOL JSM 6060 SEM at the Gazi University Electron Microscopy Unit.

Based on this information, and using the relevant literature (i.e.,Chamberlain and Matthews 1970,Podlech and Zarre 2013,Ekici et al. 2015) we decided that this specimen is new and have described it as a new taxon.

The specimens were deposited in the GAZI herbarium. The plant names mentioned here follow the International Plant Names Index (IPNI 2020).

Results

Astragalus bartinense Aytaç, Tunçkol et N. Aksoy sp. nov., sect. Tapinodes Bunge (Fig. 1).

Fig. 1 Astragalus bartinense, A – habit, B – upper surface of leaflet, C – lower surface of leaflet, D – flowers, E – calyx, F – standard, G – wing, H – keel, I – stamens, J – fruit (Photo: Hacer Muslu Çelik).

Type: Turkey. A4 Bartın, Ulus, Küre Mountains National Park, above Abdurrahman village, 550 m a.s.l., limestone rocky areas, 11 June 2016, Tunçkol 2271. (Holotype: GAZI!; Isotypes: ANK!, DUOF!).

Diagnosis: The new species is very similar to A. froedinii and A. depressus, however, it is different from A. froedinii, with hairy fruit, recurved pedicel, 10–12 mm long stipules (not 2–5 mm), 10–25 mm long peduncle (not 2–5 cm) and 5-7 mm long bracts (not 1–1.5 mm). Also, it is distinguished from A. depressus by 10–12 mm long stipules (not 2–10 mm), distinctly hairy stem and 10–25 cm long peduncle (not 0.3–8 cm) and a stipitate and glabrous ovary (not sessile and short hairy). The other distinctive character is the pale pink corolla (not whitish or yellow).

Description: Plants 15–30 cm long, shortly to distinctly caulescent and caespitose, covered with white, also black hairs in the inflorescence. Stems 5–15 cm long, glabrous at base, sparsely hirsute towards tip. Stipules 10–12 mm; free from stem and covering the internodes, lanceolate–acuminate, sparsely hairy below, ± glabrous upper side, ciliate at margin. Leaves 10–20 cm long; petiole at least 1/3 times longer than lamina and sparsely hirsute. Leaflets 5–15 × 3–10 mm long, 8–14 pairs, oblong to obovate, glabrous on upper side, sparsely hairy on underside and long ciliate at margins. Peduncles 10–25 cm long, shorter or longer than leaves and densely spreading hairy. Raceme 5–10 cm long, cylindrical, 10–30– flowered. Bracts 5–7 mm long, white membranous, triangular to linear, acuminate at apex, completely black hairy. Bracteoles 1–2 mm long, narrowly triangular to linear, covered with black spreading hairs. Pedicel 0.5–1 mm long, recurved, covered with spreading black hairs. Calyx 3–4 mm long, campanulate, covered with spreading black hairs outside; teeth 2–2.5 mm long and linear. Petals pale violet bluish pink; standard ca. 12 mm long, rounded at apex; wings 8–9 mm long, whitish-pink; keel 7–8 mm long, whitish – pink. Staminal tube slightly obliquely at apex. Ovary stipitate, glabrous. Legume 15–16 mm long, nodding, linear, slightly falcate, with short (2–3 mm) curved beak at tip, bilocular, white simple hairy, 3–5– seeded. Seeds, 2–3 × 1–1.5 mm long, reniform reddish brown, rugulose.

Flowering and fruiting: June.

Pollen structure: Polar axis (P) varies from 28.8 to 32.6 µm, while equatorial axis (E) varies from 22.1 to 25.7 µm in A. bartinense (Tab. 1). The shapes of the pollen grains are subprolate and tricolporate. Exine sculpturing (ornamentation is microreticulate-perforate in A. bartinense.

The polar axis (P) varies from 32.6 to 38.5 µm, while the equatorial axis (E) varies from 21.1 µm to 25.2 µm in A. depressus (Tab. 1). The pollen grains are prolate tricolporate. Exine sculpturing (ornamentation) is microreticulate-perforate in A. depressus.

Exine thicknesses are very close to each other and range from 0.7 to 1.4 µm (Tab. 1). The exine is 0.7–1.4 µm in A. bartinense and 0.72–1.2 µm in A. depressus (GAZI H. Duman 4462). The intine thickness average is 0.6 µm in both taxa (Fig. 2).

Fig. 2 Pollen and seed structure. Polen of Astragalus bartinense (A, B), A. depressus (C, D), and seed of A. bartinense (E, F). Scale bars: 2 µm (B, D), 5 µm (A), 10 µm (C, F), 200 µm (E).

Leaflet structure: 5–15 × 3–10 mm, oblong to obovate, glabrous on upper side, sparsely simple hairy on underside and ciliate at margin. The hairs on the lower surface and sides of the leaflets are 1–2-celled and simple. Epidermal cells have bifurcated hair-like (epicular wax) protrusions bending the membrane structures. Stomas are amphistomatic (Fig. 3).

Fig. 3 The leaflets of Astragalus bartinense: A-C – upper surface, B and C – stomata and cuticle crease, D-F – flower surface, E and F – stomata and cuticle crease. Scale bars: 10 µm (C, F), 100 µm (B, E), 500 µm (A, D).

Etymology: The name is derived from name of the city where plant was collected. The Turkish name of this new species has been proposed as “Bartın geveni” (in English: Bartın milkvetch).

Distribution and ecology: A. bartinense is only known from the type location. It is endemic to the northwestern Black Sea Region of Turkey and belongs to the Euxine element. It grows in open limestone rocky areas with the following taxa: Fritillaria pontica Wahlenb., Lathyrus setifolius L., Aristolochia pallida Willd., Tripleurospermum oreades (Boiss.) Rechf., Sedum pallidum M. Bieb. var. pallidum, Asphodeline lutea (L.) Reichb., Isatis buschiana Schischk. and Alyssum repens Baumg. ssp. trichostachyum (Rupr.) Hayek.

Astragalus depressus is generally distributed in the western and southern regions of Anatolia (Mediterranean Region) on high mountain steppes at elevations between 1500-2800 m a.s.l. (Fig. 4). It is also distributed in Europe and on the island of Cyprus. Astragalus bartinense is distributed in a different region from the other, related, taxa (Fig. 4).

Fig. 4 Distribution of Astragalus bartinense and A. depressus in Turkey.

Conservation status: The new species was collected from a single location and the IUCN assessment was not evaluated, because there was not much information about the population. With the available data, it should be kept in the NE category (IUCN 2020).

Discussion

The characteristic features of the section are acaulescent to caulescent, scapose habit with basifixed hairs; stipules obliquely, adnate to the petiole or free from it; bracts and bracteoles are present; legume usually bilocular. The new species is evaluated in section Tapinodes because of the section’s characters.

The section is represented by three species in the Old World, A. depressus, A. tetuanensis and A. froedinii.

Astragalus bartinense is close to A. froedinii in leaflet pairs and stem structure, but has longer stipules (10–12 mm long, not 2–5 mm); peduncle 10–15 mm long (not 2–5 cm); flowers spreading to nodding with age, (not erect); fruit nodding, sessile, linear, slightly falcate and hairy (not glabrous). On the other hand, it is close to A. depressus, but leaves shorter or longer peduncle; flowers pale violet or pink bluish, neither white nor yellow, usually cream when in dried condition; spike raceme cylindrical, not globose to shortly cylindrical.

Astragalus depressus is a polymorphic species. Astragalus depressus is a common species of the genus Astragalus in Europe, Turkey and Morocco. Therefore, its variations are quite wide. Over time, these differences were expressed and published as different taxa and in fact it has eight synonyms in recent studies ofPodlech and Zarre (2013). While this new species was being described and after a review of the differences and synonyms, it was given as a new taxon. There are three important differences that distinguish this new species from the others. The first is the stipitate and glabrous ovaries, the second long spike inflorescence and the third one is the petals, pale violet to bluish pink. Other variations are given inTab. 2. In the future, phylogenetic research on all the taxa of the section (Tapinodes) will contribute to the solution of these problems.

However, the distribution of A. depressus is generally of Mediterranean phytogeographical origin and distributed in the southern part of Anatolia (in the Mediterranean Region), while the new species is in the North of Anatolia (Euro-Siberian Region,Fig. 4).

The identification key of the section Tapinodes species

Comparison of diagnostic characteristics of the taxa is given inTab. 2.

Specimens examined: Turkey: A. depressus: 29.06.1952, Davis, P.H., Dodds, J.G. & Çetik, R., 19526 (E-image: E00343338!); 12.05.1965, Coode, M.J.E. & Jones, B.M.G., 877 (E-image: E00343344!); Adana: Karsantı-Torasan Dağı, Kanlıkavak District, Kepirlik, 2150 m, 15.06.1977, Ekim 1578 (ANK!); Antalya: Gömbe-Uçarsu, 10 km, meadows, 1260 m a.s.l., 18.05.2011, F. Taeb 1016 (GAZI!); Alanya: Aktaş plateau, forest scree, 1700-1750 m a.s.l., 15.05.2006, B. Bilgili 1799 (GAZI!); Akseki, Güzelsu village, scree of forest, 1450 m a.s.l., 16.05.1995, A. Duran 2465 (GAZI!); Mersin: Mut, Kırobası-Silifke, scree of forest, calcareous rocks, 19.05.2011, Z. Aytaç et al. 9777 (GAZI!); Isparta: Gelendost, Gelendost-Akşehir, W Passhöhe, bergrücken mit fels, 1850 m, 29.05.1992, M. Nydegger 46119 (GAZI!); Beyşehir, Kurucaova, Radar-Karagöl, calcareous rocks, alpine, 2000-2500 m a.s.l., 24.07.1975, Peşmen 1976 (ANK!). Kahramanmaraş: Engizek Dağı, around Kavurmaçukuru, alpine steppe, 2200 m a.s.l., 17.06.1987, H. Duman 3402 (GAZI!); Kayseri: Pınarbaşı, Mezgitli-Değirmentaş villages, Soğanlı Dağı, Aslanbeyli plateau, Kurubel-Kırınsivri hills, 1800 m, 27.5.2008, B. Bani 5967 (GAZI!); Karaman: Ermenek-Kuruseki, 1200-1300 m a.s.l., rocky places, 29.04.1990, H. Duman 4462 (GAZI!).

Other countries: A. depressus: 05.13.1965, Coode, M.J.E. & Jones, B.M.G., 945 (E-image: E00343340!); Grisebach, H.R.A., Greece (M-image: M0174795); 15.06.1895, Siehe, 262 (W-image: W0025424!); 15.06.1912, Siehe, 395 (E-image: 00343345!); Linnean Society of London Herbarium (LINN), LINN–HL 926–53, (original elements) Anon., Sweden (LINN-image: LINN2081514!); 04.1836, Chesney, F.R., 66, Syria (K-image: K000895621!); 07.1924, Embegrer, L., Morocco (RAB-image: 182782!); 19.5.1883, Mouillefarine, E., France (RAB-image: 182782!); 20.5.1851, Bourgeau, Spain (RAB-image: RAB008703!). A. froedinii: 06.05.1921, Frödin, J., ca. 1350 m, Lund University Botanical Museum (LD), (LD-image: 1085572!), Morocco (RAB-image: RAB0405097!); 1921.6.8., Jahandiez, E., 666 Morocco (RAB-image: RAB0405097!); 1921.7.13., Maire, R.P., (MPU-image: MPU132107!). A. tetuanensis: 30.05.1981, Castroviejo, S., Fernández Casas, J., Muñoz Garmendia, F., Susanna, A., 5379, Morocco (MSB-image: MSB348321!).