Centaurea lovricii Bogdanovic , Borsic , Ljubicic , Brullo & Giusso, 2022

Bogdanovic, Sandro, Borsic, Igor, Ljubicic, Ivica, Brullo, Salvatore & Giusso del Galdo, Gianpietro, 2022, Centaurea lovricii, a new species of C. sect. Centaurea (Asteraceae) from Croatia, PhytoKeys 214, pp. 97-114 : 97

1. Centaurea lovricii Bogdanovic, Borsic, Ljubicic, Brullo & Giusso sp. nov.

Figs 1 , 2 , 3B, C, D

Centaurea glaberrima var. issaea Lovrić, Taxon 31(4): 763, 1982 (nom. nud.).

Centaurea issaea Lovrić, Pos. izd. Muz. grada Šibenika 10: 191, 1983 (nom. nud.).

Type.

Croatia. Island of Vis , Blišćevac bay, calcareous rocky slopes, 16 May 2021, 43°4'23.30"N, 16°5'51.59"E, S. Bogdanović & M. Temunović s.n. (holotype: ZAGR-68512; isotypes: CAT, CNHM, ZA, ZAGR) .

Description.

Perennial herb, with several stems, sterile leaf-rosettes and woody rootstock. Stems erect, glabrous, striate, shiny green, 25-50 cm long, not winged, laxly branched. Basal leaves fleshy, shiny green, glabrous, 1-2 pinnatisect, 7-20 cm × 5-40 mm; leaflets 5-15 per side, lanceolate, linear-lanceolate to linear, or oblong lanceolate, 5-30 × 0.8-5(-10) mm, often the terminal ones lanceolate and up to 10 mm wide; young leaves oblong lanceolate with entire margin or with few lateral teeth; petioles 5-55 mm long. Median and upper cauline leaves similar to basal ones, sessile or subsessile, 1(-2) pinnatisect, 1.5-12 × 0.5-3 cm; leaflets 1-12 per side, linear-lanceolate to linear, margins entire. Synflorescence laxly paniculate, with 7-30 solitary capitula. Peduncles 1-20 cm long, apex clavate, bracts 1-8, entire. Involucre ovoid, 13-15 × 8-12 mm. Phyllaries straw-coloured, glabrous, coriaceous, dorsally with 3-7 nerves; the outer ones ovate, 6.5-8 × 2.5-3.5 mm; the median ones ovate-oblong, 10-15 × 3.5-4.5 mm; the innermost linear, 12.5-15 × 2-2.8 mm; phyllary appendages well-developed, triangular to orbicular, dark brown, appressed, densely fimbriate with 7-10 pairs of undulate fimbriae, 0.3-1.7 mm long, ending with a terminal acute tooth. Florets pink-purplish. Outermost florets sterile; corolla tube glabrous, 7.5-9 mm long; corolla lobes linear, irregular, 7.5-11.5 mm long. Disc florets fertile; corolla tube 10-11.5 mm long; corolla lobes linear, equal, 5 mm long. Stamens 12.5-13.5 mm long; filaments 4.5-5 mm long; anthers 8-8.5 mm long, dark violet. Style 16-16.5 mm long, ciliate at apex; stigmas 1.5 mm long. Achenes oblong, 2.6-3 × 1.4-1.5 mm, glabrous, dark brown up to the apex, with several irregular straw-coloured longitudinal ridges. Pappus obscurely biseriate, whitish, with bristles 0.6-2.3 mm long.

Etymology.

This species is dedicated to the Croatian botanist Andrija-Željko Lovrić (1943-2018), who was the first to collect it and consider it as a new species.

Phenology.

Centaurea lovricii flowers from May to late June, and fruits from late June to July.

Distribution and ecology.

This new species grows along the northern coast between Dragodid Bay and Oključina Bay of the island of Vis in Dalmatia, Croatia (Fig. 4 ). It grows on sea facing cliffs constituted of Triassic dolomites ( Lozić et al. 2012) at 10-100 m a.s.l., in rocky crevices together with many other rare or endemic species (Fig. 3A ). The most frequent chasmophytes occurring in this habitat are Aurinia leucadea subsp. scopulorum (Ginzb.) Plazibat, Campanula teutana Bogdanović & Brullo, Centaurea ragusina L., Helichrysum italicum subsp. pseudolitoreum (Fiori) Bacch., Brullo & Mossa, Brassica incana Ten., Limonium issaeum Bogdanović & Brullo, Pimpinella tragium subsp. lithophila (Schischk.) Tutin and Sesleria interrupta Vis. ( Bacchetta et al. 2003; Bogdanović and Ruščić 2011; Bogdanović et al. 2014; Bogdanović and Brullo 2015; Terzi et al. 2019).

Conservation status.

The single population of C. lovricii is composed of fewer than 1000 scattered mature individuals, so it can be considered Vulnerable (VU D1) according to the IUCN Red List Categories and Criteria ( IUCN 2022). It is currently distributed in a very narrow coastal belt of ca. 0.5 km2, so it has a restricted area of occupancy and only one location, but as its growing site is very steep and quite inaccessible, which makes the population unthreatened by any human disturbance, it does not qualify for subcriterion D2.

Chromosome number.

According to Lovrić (1982, 1983) and Van Loon (1987) the ploidy level of C. lovricii , previously attributed to " C. glaberrima var. issaea ", is tetraploid with 2 n = 4 x = 36 chromosomes, similarly to that of the allied species C. glaberrima and C. divergens ( Siljak-Yakovlev et al. 2005). According to Boršić (2013) the estimated ploidy level for " C. issaea " is also tetraploid.

Discussion.

Within Centaurea subsect. Centaurea , C. lovricii is most similar to C. glaberrima , particularly in the morphology of its capitula and phyllaries. Centaurea glaberrima is a species occurring in several localities in the north-western Balkans ( Nikolić et al. 2015). However, these two species show some significant differences in habit and the morphology of their leaves, capitula and achenes (Table 1 ). In particular, C. glaberrima (Figs 5 , 6 ) has a more robust and rigid habit, stems with up to 80 capitula, rigid basal leaves with leaflets linear-filiform (0.5-2 mm wide), involucre 6-10 mm long, with phyllaries up to 8 mm long, appendages straw-coloured, often tinged with pale-brown, with sparse fimbriae, outermost sterile florets with corolla tube 6-6.5 mm long and pappus bristles 0.2-0.8 mm long. In addition, the two species have different ecological requirements. Centaurea glaberrima usually behaves as a ruderal plant growing along roadsides, in dry rocky grasslands and occasionally also in rupestrian stands, whereas C. lovricii is a true chasmophyte in coastal stands. A population genetic study of some endemic Adriatic species of Centaurea using AFLPs was carried out by Boršić (2013), who showed the distinctness of the population from the island of Vis (sub C. issaea ) from C. glaberrima , but also concluded that this population shows evidence of introgression with C. glaberrima and C. spinosociliata . A phylogeny based on nrDNA internal transcribed spacer sequences revealed that C. lovricii still has an unclear phylogenetic position among the species of C. sect. Centaurea included in this study ( Boršić 2013).

Another morphologically similar species is C. divergens (Fig. 6 ), which is often treated as a subspecies or variety of C. glaberrima ( Malý 1928; Hayek 1931; Lovrić 1967-1968; Dostál 1976; Gavrilović and Janaćković 2022), but its treatment as a distinct species, as proposed by Visiani (1847) and Hayek (1901), seems to be more appropriate (see Table 1 ). It differs from C. lovricii in having a hispid stem, rigid and dull green basal leaves with linear-filiform leaflets (0.5-2 mm wide), a 6-10 mm long involucre, phyllaries that are up to 8 mm long, with up to 2 mm long fimbriae, outermost sterile florets with a 5.5-6 mm long corolla tube, and up to 1.1 mm long pappus bristles. They are also ecologically well differentiated, because C. divergens is usually a typical ruderal species, while C. lovricii is a chasmophyte.

A nomenclatural overview and lectotype designation for C. glaberrima and C. divergens , species closely related to C. lovricii , are here provided:

Figures

Figure 1. Habit of Centaurea lovricii sp. nov. Drawn by Salvatore Brullo.

Figure 2. Centaurea lovricii sp. nov. A capitulum B phyllaries C outermost sterile florets D disc florets E stigma F achenes G stamens upper part. Drawn by Salvatore Brullo.

Figure 3. Centaurea lovricii sp. nov. A habitat B plant growing in natural habitat C capitulum D basal leaves; C. glaberrima E plant growing in natural habitat F capitula G basal leaves; C. divergens H plant growing in natural habitat I capitulum. Photographed by Sandro Bogdanovic.

Figure 4. Distribution of Centaurea lovricii sp. nov. (green dots), C. glaberrima (red dots) and C. divergens (blue dots).

Figure 5. Habit of Centaurea glaberrima. Drawn by Salvatore Brullo.

Figure 6. Centaurea glaberrima (1) and C. divergens (2) A capitula B phyllaries C outermost sterile florets D disc florets E stamens upper part F style.