Trifolium aybarsii M.Keskin & Sonay, sp. nov.

(Subgen. Trifolium sect. Trifolium subsect. Aybarsii), Fig. 1, 2

Type: — TÜRKİYE. Elazığ: Yaylım mountain, upper part of BaltaŞı village, meadow, ca. 1200 m, 29 vi 1983, H.Evren (FUH 4359!).

Diagnosis: —It is closed to T. ochroleucon Hudson (Table 1), but stipules 20–30 mm (vs. 40–45 mm), upper leaves 20–30 × 8–12 mm (vs. 10–22 × 5–7 mm), calyx tube patent or subpatent hairy (vs. adpressed hairy), calyx length 11–15 mm (vs. 10–12 mm), calyx short teeth 3–4 mm, all equals and equal to tube (vs. 1.5–4 mm, two type; shorter than tube), long tooth 8–11 mm, 3 × longer than others, clearly diffused; purple at tips (vs. 6–8.5 mm, 2 × longer than others, strict or subpatent; colorless at tips), fruting calyx closed by ring (vs. closed 2-lipped callosity).

Description:—Perennial plants with a hard, woody base, up to 45 cm tall; with a distinctly diffused hairy appearance at the bottom of the stem; and with a hairy appearance at the top, slightly away from the stem. The stipules are spreading hairy and veined; the tube part is whitish, the veins are green, shorter than the free parts; the free parts are green, thin and long, narrowly elongated, narrowing slightly towards the upper part, blunt at the tip, with few but distinct veins, 20–30 mm. The leaves are opposite at the top and alternate below. Lower leaf petiole 40–100 mm, diffused hairy; middle leaflets up to 40 mm petiolate; upper ones up to 10 mm hairy. Lower leaflets 8–20 × 4–6 mm, hairy diffused along the margin, retuse-emarginate at the apex; middle leaflets 30–50 × 8–12 mm, obtuse at the apex, slightly indented, surface almost adpressed hairy; upper leaflets 20–30 × 8–12 mm; the margins of the leaflets are finely serrated, finely veined and forked at the margins. Peduncles 8–35 mm, with adpressed hairs. The inflorescence is almost spherical to ovoid, many-flowered; 15–25 mm in diameter, slightly flattened at the top. The flowers 13–15 mm long. The corolla is slightly longer than the calyx; vexillum dark brown when dry, the other parts are light yellowish brown. The calyx is 5–toothed, all teeth with purple tips and hairless, lower parts long diffused haired, one of them three times as long as the other and slightly wider, shorter teeth 1(–3)–veined and long tooth 3–nerved at base, densely hairy and erect. Flowering calyx 11–15 mm, tube 10–veined, 3.5–4 mm, diffused or almost densely hairy; long tooth 6–8 mm, apex sharp, glabrous and erect; four short teeth 3–4 mm long, pointed at the tip, almost the same length as the tube. Fruiting heads 25–35 mm, slightly elongated and ovoid. Fruiting calyx 12–15 mm, somewhat swollen, throat part closed by a hairy callus ring; tube part 4–4.5 mm; long teeth 8–11 mm, diffused laterally, short teeth 3.5–4 mm. Ovary 1–1.1 mm, glabrous. Young seed up to 1.3 mm in diameter, reddish.

Etymology: —The specific epithet of the new species refers to “Aybars” who is son of first author.

Vernacular name: —Since no local name can be observed, the name “Hilal yonca” is suggested as new Turkish scientific name (Menemen et al. 2016).

Ecology and habitat: —The Yaylım Mountain is an important area in terms of its species richness. Two doctoral theses have been written about this area. Evren (1985) identified 663 taxa in his study titled “The Flora of the Mastar, Kup, and Yaylım Mountains (Elazığ)”. Sinan (2024) reported 990 taxa in his thesis titled “The Flora of the Yaylım Mountains and Surroundings (Solhan-Genç/ Bingöl)”. Both have emphasised the habitat richness of these areas.

The habitat of the new species is not clearly indicated on the herbarium label. On the other hand, during the field studies carried out in the area, species that coexist in possible type areas were identified and these can be stated as follows: Allium ampeloprasum L, A. trachycoleum Wendelbo, Trifolium arvense L., T. campestre Schreber, T. pauciflorum d’Urv., T. pratense var. pratense, Lotus corniculatus L., Lathyrus roseus Steven, Medicago lupulina L., Vicia cracca L., Astragalus microcephalus Willd., Geranium tuberosum L., Lamium amplexicaule L., Lallemantia iberica (M.Bieb.) Fisch. & C.A.Mey., Marrubium astracanicum Jacq., Salvia multicaulis Vahl, Gundelia tournefortii L., many members of Poaceae and Cypraceae.

Phenology: —The sample collection period is at the end of the sixth month. This indicates that the specimen most likely entered its flowering and fruiting period during the sixth and seventh months. Indeed, no specimen was found during a field survey conducted in the eighth month.

Conservation status: —As there is insufficient data to determine the conservation status of the specimen, it is appropriate to retain it in the DD category.

Taxonomic comments:— Trifolium aybarsii is a new species of the Anatolian diagonal. Many endemic plants are noteworthy in the provinces located along this diagonal. Although many studies have been conducted along the diagonal, the number of endemic species in the area remains unclear and is constantly changing (Ekim & Güner 1986, Gür 2016 & 2017).

T. aybarsii resembles the species T. ochroleucon, but it is nonetheless a distinct species with its own characteristics (Table 1). The flowers are slightly longer than the calyx and are probably two-coloured. During the flowering period, one calyx tooth is approximately 2–2.5 times longer than the others, increasing to about three times longer during fruiting. The base of all teeth is triangular and broad. It is nearly 1 mm thick and long in fruiting period, with three veins at the base and one vein towards the tip. Again, all teeth are hairless at the tip and purplish. The short teeth are almost equal in size and triangular at the base, which is a special feature. In addition, the teeth begin to narrow abruptly from the base. In contrast, the long teeth are slightly wider at the base but never like the short teeth. They gradually narrow towards the tip but acute at the tip.

T. aybarsii is considered within the Trifolium section of the Trifolium subgenus. This unique calyx morphology justifies the establishment of a new subsection within Trifolium section Trifolium, highlighting the distinct evolutionary lineage of T. aybarsii. Therefore, a new subsection (Subsect. Aybarsii M. Keskin) has been defined, and this species has been classified within it.