Rubus violaceifrons P. Havlicek, Travn. & Velebil 2022, sp. nov.
Creators: name: Havlíček, Petr
name: Trávníček, Bohumil
name: Velebil, Jiří
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Rosales
Rosaceae
Rubus
Rubus violaceifrons

description: Rubus violaceifrons P. Havlíček, Trávn. & Velebil, sp. nov.
TYPE:— Central Bohemia, Praha-východ distr., Říčany town, clearing along forest road in the Říčanský les wood 40 m S of the Říčanská hájovna gamekeeper‘s lodge and 2.2 km SE of church in the Masarykovo náměstí square, scattered, 49°58’29.2”N, 14°40’13.3”E, 390 m a.s.l., 17 June 2020, J. Velebil 200711 (holotype: PR 973721 – inflorescence, PR 973722 – primocane leaves; isotypes: BRNM 829163; CB 105073; OL 38085; PR 973723, 973724, 973725, 973726, 973727; PRA 20405, 20406). Fig. 1, 2.
DESCRIPTION:—Shrub 30–100 cm tall. Primocane stems low to medium high arching, relatively thin, (4–)5–6.5(– 8) mm in diameter, angled, with flat or slightly furrowed sides, greyish light green (sometimes whitish or purplish pruinous) and sometimes dark purplish spotted in shaded places or intensively suffused with brown-red in sunlit sites, with ca. 50 mainly simple hairs per 1 cm of stem side and with numerous somewhat unequal violet (or olive green and reddish when shaded) stalked glands up to 2 mm long; prickles numerous, (9–)11–20(–28) per 5 cm of stem length, almost equal, quite slender, straight to only very slightly curved, slightly declining, with a slightly compressed base, glabrous or sparsely hairy at the base, suffused red, with a yellowish tip, (2–)2.5–4(–4.5) mm long, with a (2.0–)2.3– 3.3(–3.7) mm wide base.
Primocane leaves pedate, (3–)4–5-foliolate (when 3-foliolate then with basal lobes on lateral leaflets), leaflets usually not contiguous, almost flat, quite stiff, leathery and shiny, deep green, glabrous or with few hairs (near margins), and often with innumerable small sessile glands above, yellowish-green or only slightly greyish beneath, with simple or sometimes also with scattered tufted (mainly on veins) hairs, distinctly hairy to the touch; terminal leaflet with midlong petiolule (petiolule length 25–35% of leaflet lamina length), usually obovate, broadly obovate to suborbicular, most often slightly cordate at the base, with an almost gradually acuminate apex (5–)12–17(–19) mm long, with an almost flat, indistinctly double (periodically) serrate margin, principal teeth apiculate (sometimes with a retrorse apex), usually broader than long, with incisions 1.5–2(–3) mm long; lateral leaves slightly smaller than the terminal one, basal leaflets distinctly smaller, with petiolules 2–4(–6) mm long; petioles usually longer than the basal leaflets, 5–7.5(–9) cm long, densely hairy, with numerous stalked glands and with (5–)10–15(–20) straight or slightly curved, slightly declining prickles, round or only shallowly canaliculated at the base; stipules narrowly lanceolate.
Inflorescence conical, usually short, distal 3–5(–8) cm long part leafless. Inflorescence leaves predominantly ternate (the uppermost 1–2 leaves simple), with scattered adpressed simple hairs and shortly stalked glands above, with numerous simple and tufted (and rarely stellate) hairs beneath; axis slightly flexuous, densely hairy, with numerous stalked glands and with 5–7 prickles on 5 cm axis length, prickles almost straight, slightly declining, 2–4 mm long, inflorescence branches pointing obliquely upwards or patent; pedicels (4–)6–12(–18) mm long, densely hairy, mainly with adpressed tufted hairs, with numerous stalked glands and with 0–2(–4) acicular prickles 1–2 mm long.
Flowers mid-sized, (1.7–) 2.1–2.3 cm in diameter; sepals long pointed, 6–7 mm in length (including appendix), often with a lanceolate appendix (1.7–)2.2.–2.7(–3.2) mm long, usually reflexed after anthesis, on the back greyish, tomentose, with a white felted margin, and with numerous dark red stalked glands which are a little shorter than protruding simple hairs, sometimes also with whitish pricklets; petals white, obovate elliptical, emarginate, not contiguous, (9.0–)9.2–9.6(–10.4) mm long, (4.7–)5.3–5.7(–6.1) mm wide; stamens longer than styles, filaments white, anthers glabrous; carpels with tufted to stellate (rarely simple) hairs or glabrescent, styles distinctly dark red-violet; receptacle glabrous or with few short hairs. Collective fruit mostly well developed, subglobose, (0.7–)0.9–1.2(–1.4) cm long, 1.1–1.3 cm wide, blackish and shiny when mature, with small, numerous, (16–)20–34(–49) drupelets.
Phenology: —Flowering: June and July.
DNA-ploidy level: —Tetraploid, 2n = 4x (~28); the ploidy level was determined by Michal Hroneš at the Department of Botany of Palacký University in Olomouc. Voucher specimen: Ráby village (distr. Pardubice), forest clearing near a crossroad N of the village, 50°04’52”N, 15°48’12”E, leg. B. Trávníček, 13 Aug 2020, OL (under collection code R64/20). This ploidy level is typical of Rubus ser. Pallidi, all karyologically examined taxa of the series (twelve species) were tetraploids (Kurtto et al. 2010, Krahulcová et al. 2013, Sochor et al. 2019).
Ecology: — Rubus violaceifrons most often grows in margins, clearings and openings of coniferous and mixed woodlands and forest plantations, usually in somewhat shaded places. It is clearly a nemophilous bramble species according to the concept of Weber (1995: 296). It is usually found on permeable, moderately humid to slightly dry soils that neutral to slightly acidic. The elevation range of the species spans from 175 m a.s.l. (Káraný and Nový Vestec villages) to 590 m a.s.l (Otradovice village).
Distribution: —According to the concept of Weber (1996), Rubus violaceifrons is a “regional” bramble species: the longest diameter of its distribution area is about 150 km (Fig. 4). Currently, it is known from 42 localities dispersed in central and eastern Bohemia in the Czech Republic. The species is possibly an endemic taxon of the country, but it could be found also in southern Poland (particularly in the Kłodzko County or in Silesia). In terms of the grid system of the Atlas Florae Europaeae (for the genus Rubus, see Kurtto et al. 2010), R. violaceifrons is present in the following units: 33UWS4, 33UVR1, 33UVR3, 33UVR4, 33UVQ3, 33UWR1, 33UWR2, 33UWR3, 33UWR4.
Etymology: —The epithet “ violaceifrons ” is a reference to the intense colouration of stem parts and their stalked glands, as well as to the very conspicuous red-violet colour of styles in open flowers.
Additional specimens examined (paratypes): — BOHEMIA, phytogeographical region 6. Džbán: Kladno, v lese Milíř záp. žel. nádraží na jihozápadním okraji města, kulturní smíšená smrčina [Kladno, in the wood called Milíř W of the railway station on the SW edge of the town, mixed spruce plantation, 405 m a.s.l., 50°7‘50.0“N, 14°5‘3.0“E], 26 Jul 1980, Skalický V. (PRC!).— 7d. Bělohorská tabule: Kladno, Kožová hora jižně od města [Kladno, Kožová hora hill S of the town, 425 m a.s.l., 50°7’17.0”N, 14°6’16.0”E], 26 Jul 1980, Holub J. (PRA!); Kladno town, forest margin NNE of Kožová hora hill, [435 m a.s.l.] 50º07’06”N, 14º06’26”E, 23 Aug 2000, Trávníček B. (OL, sub coll. no. R245/00!); Kladno, j. [Kladno, S], 420–430 m a.s.l., 50º07’11”N, 14º06’28”E, 23 Aug 2000, Havlíček P. (herb. P. Havlíček!); Kožová hora [Kožová hora hill, 425 m a.s.l., 50°7’17.0”N, 14°6’16.0”E], 6 Oct 2005, Hadinec J. (PRC!); Bohemia centralis, oppidum Kladno, pagus Pletený Újedz: ad marginem silvae, ca 1.5 km situ bor.-bor.-occid. a pago [central Bohemia, Kladno town, Pletený Újezd village: on the edge of a wood ca. 1.5 km NNW of the village, 425 m a.s.l., 50°7’17.0”N, 14°6’16.0”E], 24 Jul 2007, Žíla V. (herb. V. Žíla!); Kladno town, forest margin N of Kožová hora hill, 440 m a.s.l., 50º07’17”N, 14º06’16”E, 24 Jul 2010, Trávníček B. (OL, sub coll. no. R15/10!); Kladno, při lesní cestě na Kožovou horu (modrá turist. značka), J od železničního přejezdu, ca 0.8 km Z–ZJZ od želez. stanice Kladno [Kladno, along forest road in the direction of Kožová hora hill (blue marked tourist path), S of the railroad crossing, ca. 0.8 km W to WSW of Kladno railway station, 415 m a.s.l.], 50º07’36”N, 14º06’06”E, 24 Jul 2010, Hlaváček R. (HOMP!); Kladno, ca. 0.2 km NW of the summit of Kožová hora hill, on the edge of a road, 450 m a.s.l., 50º06’55.2”N, 14º06’09.2”E, 24 Jul 2010, Lepší M. (CB 79125!); Kladno, ca. 0.8 km NNE of the summit of Kožová hora hill, an edge of a road, 430 m a.s.l., 50º07’16.9”N, 14º06’16”E, 24 Jul 2010, Lepší M. (CB 79126!); Kladno, ca. 1 km NNE of the summit of Kožová hora hill, the edge of a forest road, 420 m a.s.l., 50º07’21.4”N, 14º06’19.4”E, 24 Jul 2010, Lepší M. (CB 79127!); Malé Číčovice [Malé Číčovice village], 290–300 m a.s.l, 50º09’17”N, 14º15’22”E, 15 Sep 2001, Havlíček P. (herb. P. Havlíček!).— 11a. Všetatské Polabí: Čelákovice, Káraný, bor 0.5 km J od osady [Čelákovice town, Káraný village, pine growth 0.5 km S of the village, 175 m a.s.l., 50°10’44”N, 14°44’50”E], 25 Aug 2002, Havlíček P. (PRC!); Lysá nad Labem, Karlov, bor 0.5 km SV od osady [Lysá nad Labem town, Karlov village, pine growth 0.5 km NE of the village, 180 m a.s.l., 50°11’35”N, 14°48’25”E], 25 Aug 2002, Havlíček P. (PRC!); Stará Boleslav, Nový Vestec, bor SZ od obce [Stará Boleslav town, Nový Vestec village, pine growth NW of the village, 175 a.s.l., 50°11’16”N, 14°42’51”E], 25 Aug 2002, Havlíček P. (PRC!).— 11b. Poděbradské Polabí: Poříčany, sz. [NW of Poříčany village], 240 m a.s.l., 50º06’40”N, 14º53’43”E, 12 Oct 2000, Havlíček P. (herb. P. Havlíček!); Zvěřínek, sv. [NE of Zvěřínek village], 185 m a.s.l., 50º09’34”N, 15º00’54”E, 5 Sep 2000, Havlíček P. (herb. P. Havlíček!); Kolín, Záboří nad Labem, ca 650 m VSV kostela v Záboří [Kolín town, Záboří nad Labem village, ca. 650 m ENE of the village church], 200 m a.s.l., 50º01’30,0”N, 15º21’26,6”E, 5 Jul 2002, Lepší M. (herb. P. Lepší); Velký Osek, Veltruby, bor a lemy u železniční zastávky V u obce [Velký Osek village, Veltruby village, pine growth and belts of vegetation around railway stop E of the village, 195 m a.s.l.], 50°04’24”N, 15°12’01”E, 31 Oct 2002, Havlíček P. (PRC!).— 12. Dolní Pojizeří: Stará Lysá (Lysá nad Labem), bor (s akátem) 1.3 km s. od obce [Starý Lysá village (Lysá nad Labem town), pine growth (with black locust) 1.3 km N of the village], 210 m a.s.l., 50º14’14”N, 14º48’06”E, 7 Aug 2001, Havlíček P. (herb. P. Havlíček!); Kochánky (Benátky nad Jizerou) [Kochánky village (Benátky nad Jizerou town)], 240 m a.s.l., 50º17’12”N, 14º47’08”E, 8 Aug 2001, Havlíček P. (herb. P. Havlíček!); Stará Boleslav, paseka při trati pod vedením vysokého napětí V od železniční stanice [Stará Boleslav town, clearing near the railway under power lines E of the railway station], 180 m a.s.l., 50º12’36,9”N, 14º41’37,1”E, 3 Jul 2002, Lepší M. (herb. P. Lepší!); Benátky nad Jizerou, Luštěnice, les při silnici [Benátky nad Jizerou town, Luštenice village, wood along road, 225 m a.s.l., 50°19’08”N, 14°54’08”E], 28 Aug 2002, Havlíček P. (PRC!); Milovice, Všejany, les při cestě 1.5 km JZ od obce [Milovice town, Všejany village, wood along road 1.5 km SW of the village, 210 m a.s.l., 50°15’06”N, 14°56’19”E], 28 Aug 2002, Havlíček P. (PRC!).— 13a. Rožďalovická tabule: les při silnici mezi obcemi Lišice a Chlumec nad Cidlinou [wood along road between Lišice village and Chlumec nad Cidlinou town, 265 m a.s.l., 50º10’45”N, 15º24’51”E], 1 Aug 1988, Holub J. (PRA!); Lišice (Chlumec nad Cidlinou), les u obce [Lišice village (Chlumec nad Cidlinou town), wood next to the village, 265 m a.s.l., 50º10’45”N, 15º24’51”E], 10 Jul 1989, Holub J. (PRA!); Lišice (Chlumec nad Cidl.), les u silnice při jv. okraji obce [Lišice village (Chlumec nad Cidlinou town), wood along road on the SW edge of the village], 260–270 m, 50º10’45”N, 15º24’51”E, 29 Sep 2000, Havlíček P. (herb. P. Havlíček!); Chlumec nad Cidlinou: podél plotu uzavřeného vojenského prostoru na okraji lesního komplexu u silnice JV obce Lišice [Chlumec nad Cidlinou town: along a fence of a restricted military area in woods along a road SW of the village, 265 m a.s.l., 50º10’45”N, 15º24’51”E], 29 Sep 2000, Hadinec J. & Havlíček P. (PRC!); Nymburk, Chudíř u Jabkenic, při silnici na Loučeň, v lese nad Novým rybníkem [Nymburk town, Chudíř u Jabkenic village, along road in the direction of Loučeň town, in wood above Nový rybník pond], 230 m, 50º18’04,5”N, 15º00’56,1”E, 3 Jul 2002, Lepší M. & Lepší P. (herb. P. Lepší!). — 14a. Bydžovská pánev: Nechanice, Třesovice, doubrava 0.5 km JV od obce [Nechanice town, Třesovice village, oak wood 0.5 km SE of the village, 275 m a.s.l., 50°15’31”N, 15°41’50”E], 28 Aug 2002, Havlíček P. (PRC!); Cerekvice nad Bystřicí, doubrava SV od obce [Cerekvice nad Bystřicí village, oak wood NE of the village, 290 m a.s.l., 50°20’12”N, 15°43’53”E], 28 Sept 2002, Havlíček P. (PRC!); Hradec Králové, Libčany, doubrava při silnici SV od obce [Hradec Králové town, Libčany village, oak wood along road NE of the village, 290 m a.s.l., 50°11’45”N, 15°42’18”E], 28 Sept 2002, Havlíček P. (PRC!); Nechanice, Horní Dohalice, les SV od obce [Nechanice town, Horní Dohalice village, wood NE of the village, 280 m a.s.l., 50°17’09”N, 15°42’52”E], 28 Sept 2002, Havlíček P. (PRC!); Nechanice, Zavadilka, smrčina 0.7 km JZ od osady [Nechanice town, Zavadilka village, spruce wood 0.7 km SW of the village, 275 m a.s.l., 50°17’N, 15°39’05”E], 28 Sept 2002, Havlíček P. (PRC!).— 14b. Hořické chlumy: Dachovy 2 km S od Hořic, u lesní cesty 600 m JJV od křižovatky v Dachovech (JJZ od pramene “ Kalíšek ”) [Dachovy village 2 km N of Hořice town, along a forest road 600 m SSE of crossroad in Dachovy (SSW of Kalíšek spring)], 370 m a.s.l., 50º22’46”N, 15º38’32”E, 7 Aug 2005, Ducháček M. (PR 679759!); Hořice, Holovousy, les SZ od obce [Hořice town, Holovousy village, wood NW of the village, 335 m a.s.l., 50°22’44”N, 15°34’09”E], 2 Dec 2002, Havlíček P. (PRC!).— 15a. Jaroměřské Polabí: Vilantice (Dvůr Králové n. L.), smrčina při silnici zsz. od obce [Vilantice village (Dvůr Králové nad Labem town), spruce wood along road WNW of the village], 310–320 m, 50º22’14”N, 15º46’10”E, 10 Aug 2001, Havlíček P. (herb. P. Havlíček!); Velehrádek (Dvůr Králové n. L.), křoviny u silnice a paseka 0.3 km sz. od osady [Velehrádek village (Dvůr Králové nad Labem town), scrub along road and clearing 0.3 km NW of the village], 310–330 m a.s.l., 50º23’38”N, 15º45’15”E, 10 Aug 2001, Havlíček P. (herb. P. Havlíček!).— 15b. Hradecké Polabí: Hradec Králové, Dolní Přím, les 1 km V od obce [Hradec Králové town, Dolní Přím village, wood 1 km E of the village, 300 m a.s.l., 50°14’20”N, 15°43’45”E], 28 Sept 2002, Havlíček P. (PRC!); Hradec Králové, Těchlovice, les při silnici SV od obce [Hradec Králové town, Těchlovice village, wood along road NE of the village, 285 m a.s.l., 50°12’38”N, 15°43’22”E], 28 Sept 2002, Havlíček P. (PRC!); Nové Město nad Metují, Velká Jesenice, les 0.9 km JZ od kostela v obci [Nové Město nad Metují town, Velká Jesenice village, wood 0.9 km SW of church in the village, 275 m a.s.l., 50°21’08”N, 16°02’08”E], 13 Oct 2002, Havlíček P. (PRC!).— 15c. Pardubické Polabí: Časy (Holice), les 0.9 km s. od osady [Časy village (Holice town), wood 0.9 km N of the village, 230 m a.s.l., 50º04’45”N, 15º53’41”E], 27 Oct 2000, Havlíček P. (herb. P. Havlíček!); Pardubicko: obec Časy: okraje silnice a v borovém lese u silnice do obce Choteč ca. 1.5 km SSZ obce [Pardubice region: Časy village: ditches along a road and in a pine wood along a road in the direction of Choteč village ca. 1.5 km NNW of the village, 230 m a.s.l., 50º04’45”N, 15º53’41”E], 27 Oct 2000, Hadinec J. & Havlíček P. (PRC!); Týnec nad Labem, dispersim in colle Šibeník (236.5 m), in vicinitate oppiduli orient. [Týnec nad Labem town, scattered on Šibeník hill (236.5 m), to the E in the vicinity of the town], 225 m a.s.l., 50º02’56”N, 15º22’24”E, 10 Sep 2002, Marek M. (PR 683630!); Ráby, s. [Ráby village, N of the village, 235 m a.s.l., 50º04’52”N, 15º48’12”E], 16 Aug 2000, Havlíček P. (herb. P. Havlíček!); Ráby village, forest margin near crossroad N of the village [235 m a.s.l., 50º04’52”N, 15º48’12”E], 13 Jul 2015, Trávníček B. (OL, sub coll. no. R2/15!); Ráby village, forest margin near crossroad N of the village [235 m a.s.l., 50º04’52”N, 15º48’12”E], 13 Aug 2020, Trávníček B. (OL, sub coll. no. R64/20!). — 41. Střední Povltaví: Radlík (Praha-západ distr.), scrub along a forest road 230 m SSW of summit of Spáleniště hill (421 m) NW of the village, 405 m a.s.l., 49º54’49.6”N, 14º29’14.2”E, 3 Jan 2021, Velebil J. (herb. J. Velebil, 210101!). — 43b. Miličínská vrchovina: Neustupov, Otradovice (Votice), lem silnice a smrčina 0.4 až 1 km j. (jjv.) od obce [Neustupov town, Otradovice village (near Votice town), ditches and spruce wood along a road 0.4–1 km S (SSE) of the village], 570–600 m a.s.l., 49º38’06”N, 14º41’01”E, 17 Aug 2001, Havlíček P. (herb. P. Havlíček!); Otradovice (Benešov distr.), scrub along a road in a wood on the S margin of the village, 570 m a.s.l., 49º38’08.5”N, 14º40’55.1”E, 17 Jul 2020, Velebil J. (herb. J. Velebil, 1707113!).— 55e. Markvartická pahorkatina: Vrch Loreta mezi obcemi Podhradí a Hlásná Lhota [Loreta hill between the villages of Podhradí and Hlásná Lhota, 380 m a.s.l., 50°25’23.0”N, 15°17’46.0”E], 28 Jul 1987, Holub J. (PRA!).— 56c. Trutnovské Podkrkonoší: Svoboda nad Úpou, smrčina 1.5 km JJZ od kostela v obci [Svoboda nad Úpou town, spruce wood 1.5 km SSW of the village church, 575 m a.s.l., 50°36’39”N, 15°48’35”E], 25 Nov 2002, Havlíček P. (PRC!).— 56e. Červenokostelecké Podkrkonoší: Červený Kostelec, jv. [Červený Kostelec town, SE of the town, 425 m a.s.l., 50º28’15”N, 16º05’51”E], 31 Oct 2001, Havlíček P. (herb. P. Havlíček!).— 57a. Bělohradsko: Hořice, Lukavec u Hořic, les při silnici 0.7 km JV od obce [Hořice town, Lukavec u Hořic village, wood along road 0.7 km SE of the village, 370 m a.s.l., 50°23’07”N, 15°37’32”E], 2 Dec 2002, Havlíček P. (PRC!).— 64a. Průhonická plošina: Klánovice: PR Klánovický les, u lesni cesty (červená turistická značka), ca 0.5 km VJV od budovy železniční stanice Praha-Klánovice, ca 1.5 km J–JJZ od kostela Nanebevzetí Panny Marie, na okraji lesní paseky, u příkopu lesní cesty [Klánovice village: Klánovický les Nature Reserve, along a forest road (red-marked tourist path), ca. 0.5 km ESE of the Praha-Klánovice railway station building, ca. 1.5 km S–SSW of the Nanebevzetí Panny Marie church, margin of a forest clearing, along ditch of forest road], 255–260 m a.s.l., 50º05’07,1”N, 14º40’11,3”E, 15 Oct 2019, Hadinec J., Hlaváček R. & Trunečková L. (HOMP!); Praha-Klánovice: Klánovický les; v porostech ostružiníků v okrajích duboborového lesa podél protihlukové stěny u žel. trati na žluté značce východně žel. nádraží Praha-Klánovice [PrahaKlánovice village: Klánovický les wood; bramble scrub on the edge of an oak-pine wood along an anti-noise barrier and railway on the yellow-marked tourist path E of Praha-Klánovice railway station, 255 m a.s.l.], 50º05’16,1”N, 14º40’02,3”E, 15 Oct 2019, Hadinec J., Hlaváček R. & Trunečková L. (PRC!); Říčany (Praha-východ distr.), along a forest road in the part of the Říčanský les wood called K Srnčímu palouku, about 200 WNW of the Říčanská hájovna gamekeeper’s lodge, S margin of the town, 380 m a.s.l., 49º58’33.5”N, 14º40’04.7”E, 19 Oct 2018, Velebil J. (herb. J. Velebil, 181012!); Praha-Újezd (Hlavní město Praha distr.), light mixed wood in the W part of the Milíčovský les Nature Monument, 290 m a.s.l., 50°01’14.2”N, 14°31’44.0”E, 20 Oct 2021, Velebil J. (herb. J. Velebil, 211025!).— 64b. Jevanská plošina: Světice (Praha-východ distr.), along a forest road near the Říčanská hájovna gamekeeper’s lodge 400 m NE of the football field (situated on the N margin of the village), 390 m a.s.l., 49º58’28.8”N, 14º40’12.6”E, 30 Sep 2017, Velebil J. (herb. J. Velebil, 170942!); Říčany (u Prahy): v okrajích červ. znač. turistické cesty v mladé smrkové výsadbě na SV okraji města [Říčany town (by Prague): along a red-marked tourist path in a young spruce planting on the NE edge of the town, 365 m a.s.l., 49°59’56.0”N, 14°40’59.0”E], 20 Aug 1999, Hadinec J. (PRC!).
Taxonomy: —Most of the morphological characters of Rubus violaceifrons classify this species as a member of R. ser. Pallidi, although it shares a few features with members of R. ser. Glandulosi (see the characterizations of these series, for example, in Weber 1995, Zieliński 2004). The classification into R. ser. Pallidi is supported by only slightly unequal shapes of stalked glands and almost uniform prickles, without shape transitions between them (particularly on primocane stems), by leaves on primocanes usually 4–5-foliolate (not 3-foliolate as is typical in R. ser. Glandulosi) and by sepals usually reflexed after anthesis. On the other hand, the only two characters that this species shares with members of R. ser. Glandulosi are a greater density of stalked glands on stems than is usually present in R. ser. Pallidi and relatively thin prickles. Moreover, the presence of hairs on primocane stems and the absence of a tomentose indumentum on leaves beneath in R. violaceifrons are not in conflict with the characterization of R. ser. Pallidi. Rubus violaceifrons has leaves almost without hairs above (or these hairs are rare), which is the only character that does not match the delineation of R. ser. Pallidi (leaves usually with scattered hairs).
There are three bramble species that are morphologically similar to and sympatric with Rubus violaceifrons: R. scaber Weihe in Bluff & Gingerhuth (1825: 683), R. josholubii (both from R. ser. Pallidi) and R. guentheri (R. ser. Glandulosi). The most similar species to R. violaceifrons in most characters of stem indumentum is R. josholubii. These two species have quite similarly shaped prickles and stalked glands on stems, but R. josholubii clearly differs in having a smaller density of these stalked glands (only 20–30 per 1 cm of stem side length) on primocane stems, which are usually round or obtusely angled (not distinctly angled as in R. violaceifrons), with longer (5–7 mm) prickles, leaves with scattered hairs above (10–30 per cm 2 of leaf surface) and longer sepals (7–12 mm), which mostly embrace the fruits. Similar to R. violaceifrons in the shape of leaves is R. scaber; however, the latter is easily identifiable based on its different shape of prickles (distinctly more declining and usually also more curved), shorter stalked glands (only up to 0.6 mm long) on primocane stems, leaves with numerous hairs above (20–100 hairs per 1 cm 2 of leaf surface) and styles yellowish-green (not reddish as in R. violaceifrons); R. scaber most often has only 3-foliolate primocane leaves whereas those of R. violaceifrons are usually 4–5-foliolate. Rubus violaceifrons somewhat resembles stouter individuals of R. guentheri, mainly in the intensity of the red-violet colouration of its stalked glands and styles in open flowers as well as the shape of the terminal leaflet. However, R. guentheri has thinner and prostrate primocane stems which are usually round, without or with sparse hairs only; it also differs in mostly having only 3-foliolate primocane leaves with scattered hairs above (10–40 hairs per 1 cm 2 of leaf surface), not hairy to the touch beneath, sepals often embracing the fruits, and stamens shorter than styles. For detailed comparison see Table 1.
description: Published as part of Havlíček, Petr, Trávníček, Bohumil & Velebil, Jiří, 2022, Rubus violaceifrons (Rosaceae), a new bramble species from Bohemia (Central Europe, Czech Republic), pp. 241-254 in Phytotaxa 568 (3) on pages 242-249, DOI: 10.11646/phytotaxa.568.3.1, http://zenodo.org/record/7223616