﻿Centaurealovricii, a new species of ﻿C. sect. ﻿Centaurea (Asteraceae) from Croatia

﻿Abstract A new species, Centaurealovricii, is described and illustrated from the island of Vis (Dalmatia, Croatia). It occurs on northwest-facing calcareous cliffs near the sea, where it grows with several other rare endemic species. Centaurealovricii is morphologically similar to C.glaberrima and C.divergens of C.sect.Centaurea, from which it differs in having more succulent leaves with larger and less incised leaflets, bigger capitula, larger phyllaries with more developed appendages and denser and undulate fimbriae, larger florets, bigger achenes, and longer pappus. Its morphological features, distribution, ecology, conservation status and taxonomic affinities are examined. In addition, a new iconography and lectotypification for C.glaberrima and C.divergens is provided.


Introduction
The genus Centaurea L. is one of the largest genera in the family Asteraceae. In its current circumscription as a natural group, it includes about 250 species Garcia-Jacas 2007, 2009). It is mainly distributed in the Euro-Mediterranean and
Etymology. This species is dedicated to the Croatian botanist Andrija-Željko Lovrić (1943Lovrić ( -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 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 km 2 , 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.
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 1967Lovrić -1968Dostál 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.
Hayek. Here we select the central specimen, which fits Tausch's description, as lectotype for the name C. glaberrima. One year later, Visiani (1829) described C. punctata from Duare [Zadvarje] in Dalmatia. We consulted the type specimen in PAD (PAD -HD02644), which fits Visiani's description given in the protologue. In fact, the morphology of the specimen perfectly corresponds to Tausch's description of C. glaberrima. Therefore, we here designate this specimen as a lectotype and include the name C. punctata as a synonym of C. glaberrima.