Silene isabellae Selvi & Bianchi, 2023

Selvi, Federico, Gonnelli, Cristina & Bianchi, Elisabetta, 2023, Silene isabellae (Caryophyllaceae), a new campion species from serpentine soils of Albania, PhytoKeys 227, pp. 123-134 : 123

Silene isabellae Selvi & Bianchi sp. nov.

Figs 1 , 2 , 3A-C

Type.

Albania, Krujë, verso Qafë Shtamë, pendice ripida del monte sopra la fonte lungo la strada prima del passo, sottobosco della foresta rada di P. nigra , suolo roccioso ultramafico (serpentino), 1100 m elev., 41°31.33'N, 19°53.27'E; F. Selvi, E. Bianchi, I. Colzi & A. Coppi, 12 Jul 2022 (holotype: FI068201 ; isotypes: K, G, TIR) .

Diagnosis.

Silene isabellae differs from S. noctiflora by the perennial habit with stoloniferous stems forming thick mats (instead of annual), the sparsely and shortly glandular-pubescent stem (vs. densely hairy), the basal leaves of the sterile stems present and widely obovate-spathulate (vs. absent), the cauline leaves linear-lanceolate (3-5 mm vs. ovate-lanceolate 25-35 mm wide), with shortly ciliate margins (vs. densely pubescent on both surfaces), the longer calyx teeth (ca. 8.5 vs. 7.0 mm), the corolla unscented and open during daytime (instead of scented and opening at evening), the petal lobes dentate (vs. entire), the fruiting calyx with prominent longitudinal ribs and the longer carpophore (6-7 vs. 2-3 mm).

Description.

Perennial herb forming thick mats, with branched stoloniferous stems thickened at the nodes. Flowering stems up to 40 cm, rigid, usually 1-4 branched in the upper half, rarely simple, shortly glandular-pubescent. Basal leaves mostly appressed to the ground, 30-80 × 8-18 mm, tapering into the petiole, widely obovate-spathulate, apiculate at tip; leaf blade thick, glabrous and finely papillose on both surfaces, shortly ciliate at the margins (hairs ca. 0.15 mm). Cauline leaves in pairs of 4-5, the uppermost narrowly lanceolate to almost linear, 30-50 × 3-5 mm, acuminate, the mid- and upper ones much shorter than the internodes, finely ciliate along margins with glandular and simple hairs on both surfaces. Inflorescence with 1-4 branches each bearing a single flower, rarely simple; branches finely glandular-pubescent, with two linear-lanceolate leaf-like bracts 6-8 mm long. Flowering calyx narrowly cylindrical, 25-30 mm, including teeth 8.2-8.6 mm, linear-lanceolate, surface glandular-pubescent, veins tinged with purplish, reticulate especially in the upper half; fruiting calyx obconical, truncate at the base and swollen at the middle, up to 13 mm wide, with 5-6 prominent longitudinal ribs. Corolla spreading 19-21 mm wide, petals 25-30 mm long (claw 15-20 mm long and slightly exserted), divided to ca. 1/3 in two lobes dentate at the outer margin, pale pink above, tinged with mauve red beneath; coronal scales exserted, truncate, nearly white; styles 3. Capsule smooth and glossy, ovoid-conical, 13-15 × 4-5 mm, dehiscing with 6 teeth curved outwards, carpophore 6-7 mm. Seeds ca. 1.1 × 0.83 mm, reniform, with surface finely papillose-tuberculate in concentric crests around the hilum, dark brown to blackish.

Etymology.

This species is dedicated to the first author’s wife, for her continuous support and advice during many botanical trips across the Mediterranean and the Middle East.

Phenology.

Flowering is from June to early July; fruiting is from end of June to end of July, depending on slope aspect and altitude.

Distribution and ecology.

Silene isabellae is likely endemic to central Albania, precisely to the ultramafic sectors of the Skënderbëut mountain range running along the border between the districts of Krujë and Mat (Fig. 4 ). We could not observe it in other parts of this mountain range with calcareous soil. Additionally, we could not find it during our botanical trips across other ultramafic mountain areas of the country (amongst which were Tropojë, Pashtrik, Lurë, Bulqizë, Shebenik, Shpat, Moravë and Vallamarë), suggesting a restricted range and, possibly, the reason why this species has remained unknown until present. The plant is found in patches in the understorey of the open Pinus nigra forests and in the rocky grasslands on the mountain slopes around the pass Qafë Shtamë, between 1100 and 1600 m a.s.l., but possibly even higher (Fig. 2A, B ). Slope aspect was prevalently south and south-west. This area is geologically characterised by vast outcrops of ultramafic rocks hosting a rich serpentine flora including remarkable Balkan endemics, such as Forsythia europaea Degen & Bald., Festucopsis serpentini (C.E. Hubb.) Melderis and the Ni-hyperaccumulator Odontarrhena smolikana (Bald.) Španiel, Al-Shehbaz, D.A.German & Marhold, subsp. Odontarrhena smolikana glabra ( Nyár. ex Markgr.) L.Cecchi & Selvi. We assume that S. isabellae is an obligate serpentine endemic.

Conservation status.

Silene isabellae grows in a mountain area which has been subjected for a long time to grazing mainly by sheep and goats. This ancient land use form has implied the creation and conservation of large grassland areas at the expenses of the forest. Fire is also a recurrent disturbance especially to the pine forest on the mountain slopes. Over the area that we could visit (ca. 5 km2), the species was relatively frequent, though discontinuously distributed. Based on the present state of knowledge, its range and extent of occurrence seem quite restricted, suggesting categorising it as "nearly threatened" (NT), mainly according to IUCN criterion B ( IUCN 2012). However, more field studies are needed to define the correct conservation category of this species.

Discussion.

Silene isabellae shows morphological affinities with taxa of Silene subg. Behenantha (Otth) Torr. & A. Gray sect. Silene Elisanthe (Fenzl ex Endl.) Ledeb. and is assumed to belong here. This is a well-defined group supported by molecular evidence ( Jafari et al. 2020) that includes annual, biennial and perennial species with large flowers, solitary or in dichasia, often dioecious, with bifid petal limb, prominent coronal scales, often five styles, capsule without basal septa dehiscing with 6 or 10 teeth and a very short carpophore ( Chater et al. 1993). In Europe, the section includes widespread species, such as S. latifolia Poir., S. dioica (L.) Clairv. and S. noctiflora L. ( Prentice 1978). The latter species, described by Linnaeus (1753) from Sweden and Germany ("Habitat in Suecia, Germania"; see Jonsell and Jarvis (1994)), is apparently the more closely related one to S. isabellae , with which it shares the thick stem, the few-flowered inflorescence, the texture and shape of the calyx, the usually hermaphrodite flowers with three styles and the reniform seeds with a nearly identical ornamentation pattern. On the other hand, S. isabellae differs from S. noctiflora in several striking characters (see Table 1 ). Most importantly, it is a perennial plant forming thick mats with sterile stoloniferous stems and basal leaves (Fig. 1A ), while S. noctiflora is annual with usually a single stem and lacking basal leaves. The latter is also different in the dense and long pubescence of the lower leaves and stems which are lacking in S. isabellae , where the lower leaves are nearly glabrous and the lower stem is very shortly glandular-pubescent. The flowers of S. isabellae are open during daytime and unscented, while S. noctiflora is characterised by scented flowers with petals enrolled during daytime, opening in evening and night. Moreover, the petal lobes of the latter are entire or nearly so, while these are distinctly dentate in the Albanian plant (Figs 1B , 2D, E ). The fruiting calyx is more distinctly truncate at the base and obconical, provided with prominent veins forming longitudinal ribs (Figs 1C , 2D ). The capsule is borne by a longer carpophore (Fig. 1D ). Additional evidence comes from the comparison of the chorological and ecological traits of the two taxa. In fact, S. noctiflora is widespread in Central and Eastern Europe ( Jalas and Suominen 1988), including Serbia, Kosovo and Methojia, where it occurs south of Priština, on the eastern rim of the Kosovo Basin ( Prodanović et al. 2016; Fig. 4 ). The plant is not known from Albania (according to Vangjeli (2015), Pils (2016); Barina et al. (2018)) and there is, thus, no range overlap with S. isabellae . Moreover, S. noctiflora is a weed usually growing in ruderal places, arable fields, cultivated ground and other synanthropic habitats, usually in lowland areas ( Chater et al. 1993).

Silene isabellae shows a weak morphological affinity also with the taxa of the S. vallesia group [sect. Silene Auriculatae (Boiss.) Schischk.]. This group includes taxa endemic to some mountain regions of southern Europe (Fig. 4 ), in France ( S. petrarchae Ferrarini & Cecchi), the western Alps ( S. vallesia L. subsp. vallesia ), the Apuan Alps in Italy ( S. pichiana Ferrarini & Cecchi), the central Apennines ( S. cattariniana Ferrarini & Cecchi) and the Balkan massifs [ S. vallesia subsp. graminifolia (Vis ex. Rchb.) Nyman, Ferrarini and Cecchi 2001]. Similarities are in the perennial habit with stoloniferous stems forming mats, the glandular-pubescent stems and leaves, the few-flowered inflorescence, the large flowers with narrowly cylindrical and reticulate-veined calyx, truncate at base, the corolla with bifid petals, the conical-ovoid capsule and the reniform seeds with a similar surface ornamentation. However, the only taxon of this group occurring in the Balkans and Albania, S. vallesia subsp. graminea , is strongly differentiated from S. isabellae in the much smaller size of the plant, the shape of the leaves (narrowly linear-lanceolate), the usually single flower per stem and other features of the calyx teeth and capsule (Table 1 , Fig. 3G ). Moreover, this taxon is only found in the Alpine massifs of the north-east of the country in the district of Kükes and close to the border with Kosovo and Macedonia, such as Mt. Pashtrik, Mt. Gjallica and Mt. Koritnik, where it reaches the southern limit of its distribution. This taxon is, thus, likely to be allopatric and geographically isolated with respect to S. isabellae , which is found over 80 km to the southwest (Fig. 4 ). Based on Vangjeli (2015), S. vallesia subsp. graminea is found in the alpine belt at 1700-2000 m a.s.l., thus, at higher elevation than S. isabellae and is typical of calcareous substrates especially limestone ( Ferrarini and Cecchi 2001; Pils 2016).

Silene isabellae is apparently found only on serpentine soils. Thanks to this specialisation, the plant can be categorised as a “metallophyte”, being able to cope with the typical chemical and physical anomalies of the serpentine soils and especially the poverty in nutrients, the high levels of Mg and in trace metals like Ni, Zn and Cr ( Wójcik et al. 2017). We plan further studies to assess the concentration of these metals within the plant and, consequently, the strategies that it adopts to thrive on such hostile soils. Adaptation to serpentine soils is not uncommon in the genus Silene , being found in several other taxa of especially the Balkan flora. According to Stefanović et al. (2003), the Balkan countries host seven taxa of this genus that can be classified as obligate serpentine endemics, while others are found on serpentine as well as non-serpentine soils (the so-called "facultative serpentinophytes"). The distant phylogenetic position of these species suggests that ecological speciation driven by the "serpentine factor" has occurred through multiple and independent events, as in other plant groups of the Mediterranean and Balkan flora ( Cecchi and Selvi 2009; Cecchi et al. 2011, 2013). Remarkably, some of the serpentine-tolerant species were also found at the same locality of S. isabellae , such as S. paradoxa L., S. italica L., S. saxifraga L., S. vulgaris L. subsp. prostrata (Gaud.) Schinz & Thell. and S. damboldtiana Greuter.

Silene isabellae shows some variation in quantitative characters associated with site conditions. Plants from the coniferous forest at lower altitude (1000-1200 m a.s.l.) were characterised by taller flowering stems and larger leaves, in particular those of the sterile stems. In plants from open and rocky sites, we observed a general reduction in the size of the plants, also associated with altitude (above 1400 m a.s.l.), while qualitative characters remained constant.

Additional specimens examined.

Silene isabellae : Albania. District of Kruje , Qafë Shtamë, rocce di serpentino nella foresta di Pinus nigra , ca. 800 prima del passo, 41°31.35'N, 19°53.32'E, 1100 m elev., 30 Jun 2018, F. Selvi & I. Bettarini ( FI053966 ); District of Krujë, Qafe Shtamë, pascoli rupestri e margini di boscaglia rocciosa lungo la pista che sale dal passo verso Nord, suolo ultramafico (serpentino), 41.5251°N, 19.5251°E, 1150-1450 m elev., 12 July 2022, F. Selvi, E. Bianchi, I. Colzi & A. Coppi ( FI068202 ) .

Silene noctiflora : Austria. Kärnten. Lavanttal: auf dem Autobahn-Rastplatz in St. Andrä, Bezirk Wolfsberg , Gemeinde Sankt Andrae , Katastralgemeinde Kollegg , 46°47'08"N, 14°48'46"E, 450 m elev., 27 May 2008, Helmut M. s.n. (GJO 0041410); Österreich, Steiermark; Steirisches Randgebirge, Westliches Grazer Bergland; Bezirk Graz (Stadt); Gösting, Ruine Gösting, 47°06'13.44"N, 15°22'48.28"E, 541 m elev., 6 September 2010, Leonhartsberger S., (GJO 0062960); Windische Bühel, Kreuzberg bei Leutschach, Oberfahrenbach - Gamlitz - Karnerberg, Gasthof Eichbergho, 46.725°N, 15.45833°E, 07 November 1989, Maurer W. s.n., (GZU 000239138) ; Belgium. Moissons, Hackerinver , July 1863, Thieleus Armand; cultivè de cinq pieds sauvages trouvés en 1865 entre Haekendover (Brabant) et Overhespen ( Liège), July 1866, (FI) . Czech Republic. Bohemia, distr. Český Krumlov. VÚ Boletice: Nová Víska, okraj cesty přes louky 6 km JV od kostela v Křišťanově, 48.86556°N, 14.07°E, 14 July 2017, Grulich V. (BRNU 636522); Moravia centr., distr Brno : inter segtes ad pedem collis Zlobica dicti situ septentr-orientali ad oppido Kuřim, 280 m elev., 23 July 1974, Dvořàk F. (FI) . France. Environs de Strasbourg, 1805, Nestler C. G. sn, (G00215384); Douai (Nord), abondant dans un jardin où il a peut-être ètè introduit accidentallement, 26 July 1882, Maugin (FI); Versailles, 17 August 1853, Caruel L. (FI) . Germany. Thuring, 1822, Wallroth K.F.W. sn, (G00215386) . Italy. Luoghi erbosi presso Cretone di Tornimparte ( L’Aquila), 1200 m elev., 10 September 1971, Pelliccione G. (FI), Valle del Lagaccio , Liguria, June, Baglietto (FI); Cult. nell’Orto Botanico Sperimentale di Vallombrosa , 29 August 1894, Solla n. 1413 (FIAF); Giardino dei Semplici, 1830, Ricasoli (FI) .

Silene vallesia subsp. graminea : Albania. Velika Golia , 1700 m elev., 17 July 1904 (FI); Hais Patrik An Felsen in der Gipfelregion , 1800 m elev., 24 July 1877, I. Dolfler (W); Aufdem Berge Patrik bei Prizzen , 1900 m elev., 20-21 July 1936, O.V.E. Behr (FI); Prizren : Mt. Pastrik in graminosis alpinis, 21 July 1936, Skrivanek ( BP591483 ); Distrikt Hasi, Pastrik, An Felsen in der Gipfelregion, 24 July 1918, Dörfler & Ignaz ( BP455289, BP455288 ) . Bosnia and Herzegovina. Gipfelregion der Golia: Sudskamn (?) der Velica Golja, 1700 m elev., 18 July, J. Stdlmann & F. Faltis (FI); KameKnica bai Livno, 1800 m elev., 27 July 1897, E. Brandis (PAD) . Croazia. Ex rupibus Dinaricis ad … Dalmaticae , Herb Levier (FI); In saxosis apricis, Dinara , Ghnjat , Prologh , Visiani (PD); Mont Ghnjat (PAD); In dorso apricot et saxoso Mts. Dinara , July , 51K (Jos. Kargl) (PAD); Am Chemeschniza am Prolog , 18 July 1868, Th Pichler (PAD); Dalmatien M. Prolog, 18 July 1868, Th. Pichler (TSB); Croatia. Velebit in lapidosis herbosis m. Risioica supra Allau, alt. ca. 1400 m, 1908, G. Lengyel ( PI042104 ); In montib. Dalmatia, s.d., R. Visiani (HAL0012278) . Montenegro. In saxosis excelsioribus M. Durmitor, 870, J. Panic (PAD) .

Figures

Figure 1. Silene isabellae A whole plant B flower with calyx and corolla C fruiting calyx D capsule and carpophore E seed. Original drawing by Laura Vivona.

Figure 2. Field photos of Silene isabellae A habitat B, C whole plants in natural habitat D inflorescence with flowers and fruiting calyces E flower F basal leaves G flowers at late stage H seed.

Figure 3. Calyx teeth, capsule, and margin of basal leaves of Silene isabellae (respectively A-C), S. noctiflora (respectively D-F) and S. vallesia subsp. graminea (respectively G-I).

Figure 4. Distribution of Silene isabellae, S. noctiflora (partial) and the taxa of the S. vallesia L. group.