Type:— HUNGARY. Vas County, Szentpéterfa (Petrovo Selo), 2.6 km E of the village along the road to Ják, ”Szentpéterfai-erdő” forest, Scots pine plantations; N47.097500°; E16.523889°; 240 m, 16.9.2013, fruiting, G. Király (holotype: BP732260 and BP732261 (parts of the same specimen); isotypes: BP733730, BP733731, GJO, GZU, LJU, OL, W)

Description: Shrub, usually up to 80 cm tall. First-year stems low-arching, rooting at apex, bluntly angled, 3–7 mm in diameter. Sides ± flat or infrequently slightly convex, green or only slightly reddish when exposed to sun, with few 0.2–0.3 mm long hairs (later often glabrescent) and with 0–7(–12) stalked glands (0.3–0.5 mm long) per 1 cm length of stem side. Prickles 8–14(–18) per 5 cm length of stem, usually on angles, compressed and abruptly broadened at the base, straight or indistinctly curved, declining, (1–) 2.5–6 mm long, yellowish with sometimes purplish tip. Leaves pedate, 5-foliolate, usually dark green, smooth to the touch, almost glabrous above (with few adpressed hairs on the veins), and with scattered 0.2–0.5 mm long hairs on the leaf margin; grayish-green and dense tomentose beneath, with felted hairs. Leaflets slightly imbricate, terminal ones with petiolules 17–31% as long as its lamina, ovate, slightly cordate or rounded at the base, gradually tapering to an acuminate apex 15–20 mm long. Basal leaflets ovate, (0.75–)0.9–1.1× as long as the petiole; petiolules 2–5 mm long. Indentation markedly uneven, teeth cuspidate, distinctly broader (2–4 mm) than long (1–2 mm). Petioles sparsely hairy, with many ± sessile and few stalked glands and with 14–20 curved prickles. Stipules filiform, ca. 0.5 mm broad, with sparse pilose hairs and stalked glands. Inflorescence paniculate, truncate near apex, conspicuously few-flowered, with patent branches, distal 2–8 cm leafless, below with 3-foliolate leaves; indumentum of inflorescence leaves is similar to those of the sterile stems. Inflorescence axis densely pubescent, with (5–)15–50 stalked glands per 1 cm length. Prickles 4–18 per 5 cm length of axis, slender, subulate, slightly curved or straight, declining, 2–5 mm long. Pedicels 0.5–1.5 cm long, densely pubescent, with 3–30 stalked glands; prickles 5–20, ± straight, 0.5–2 mm long. Sepals 6–9 mm long, greyish-felted with scattered stalked glands and slender pricklets, entirely reflexed after anthesis. Petals early falling, not touching each other, light pink, ± spathulate, (5–)6–7(–8) mm broad and (9–)10–13(–15) mm long, emarginate or sometimes rounded at the apex. Stamens somewhat longer than the light green styles; anthers glabrous, yellow; filaments whitish. Carpels and receptacle glabrous. Flowering VI–VII.

Iconography and photos of the species are shown in Figures 1 and 2.

Taxonomical remarks: Rubus gayeri is easily distinguishable from the majority of the representatives of ser. Micantes in the region (R. balatonicus, R. clusii and the newly described R. slavonicus) by the strongly different shape of leaves and by pink petals. It also differs from R. balatonicus and R. slavonicus by having reflexed sepals after anthesis, from R. clusii by the considerably lower number of stalked glands on the sterile stems. Nevertheless, R. liubensis W. Maurer 1979: 142 is separable from R. gayeri only on the basis of substantial morphological analysis (see Table 1). The main diagnostic characters of R. gayeri against R. liubensis are the higher number of prickles on the petiole, the density of stalked glands on the pedicel and on the surface of the sepal, and the glabrous ovary. R. liubensis was described as a member of ser. Rhamnifolii (Bab.) Focke (1877: 125) by Maurer (1979), but later it was transferred to ser. Discolores (P. J. Müll.) Focke (1914: 152) by Weber & Maurer (1991). However, due to its stalked glands on sterile stem, inflorescence axis and stipules, its proper position is undoubtedly in ser. Micantes.

Etymology: The name “ gayeri ” refers to Gyula Gáyer (1883–1932), outstanding botanist coming from western Hungary; expert in Rubus, author of the first complete Hungarian identification key of blackberries (Gáyer 1924 –25).

Distribution: We could not find any former collection of the species in herbaria examined, thus, we describe its range solely based on own collections and observations. Rubus gayeri is a regional bramble species with main part of the distribution area in western Hungary (“Nyugat-magyarországi peremvidék” macroregion), also occurring in south-eastern Austria and northern Slovenia. The range of the species is approx. 120 km long and 80 km broad in SE-NW direction on the eastern foothills of the Alps, its southernmost record is located near the town Lenti along the Hungarian-Slovenian borderline, whereas, the northernmost one is located near Fertőszentmiklós at the periphery of Lesser Plain (“Kisalföld”) (Figure 5a, Appendix 1). It is widespread in western Hungary, where it is abundant in Őrség and Göcsej Hills, scattered in the Kemeneshát and Sopron –Vasi-sík regions. In Austria, R. gayeri was recorded in southern Burgenland, and at a single locality south of Graz in Styria. In Slovenia it is scattered in the Goričko region. In terms of altitude, R. gayeri grows only in hilly environment and is missing in the submontane belt of the region; the recorded localities range from 143 to 380 m a.s.l.

Ecology and biogeography: R. gayeri is moderately thermophilous and often strikingly suffers from heat stress and low relative air humidity in summer. It prefers nutrient-poor, acidic, semi-dry to moist or occasionally waterlogged soils, it is most abundant in areas covered by tertiary clayey and gravelly sediments; whereas it is absent both from nutrient-rich soils of higher altitudes and base-rich soils of loess-covered areas. Originally, it was connected with acidophilous oak-hornbeam and beech forests and forest fringes, expanding later to secondary coniferous woods of base-poor soils (Figure 6a). Typical companion species of bramble are R. bifrons Vest 1821: 163, R. clusii, R. holosericeus Vest 1821: 163, R. radula Weihe (in Boenninghausen 1824: 152), and R. styriacus. The considerably rapid increase of coverage of Scots pine plantations in western Hungary from the 1950 s has presumably played a prominent role in the migration of the species; the most abundant stands were found in this habitat type. According to our data, R. gayeri belongs to the few native brambles in the Pannonian Basin which migration and recent distribution was highly influenced by modern-day anthropogenic land-use modifications.