Allium dinaricum Bogdanović, Anačkov, Ćato, Borovečki-Voska, Salmeri & Brullo, 2024

Bogdanović, Sandro, Anačkov, Goran, Ćato, Sebastian, Borovečki-Voska, Ljiljana, Salmeri, Cristina & Brullo, Salvatore, 2024, Allium dinaricum (Amaryllidaceae), a new species of A. sect. Codonoprasum from the Balkan Peninsula based on morphology and karyology, Willdenowia 54, pp. 183-196 : 184-189

Allium dinaricum Bogdanović, Anačkov, Ćato, Borovečki-Voska, Salmeri & Brullo , sp. nov. – Fig. 1–6.

Holotype: Croatia, Mt Velebit , above Velike Brisnice, in calcareous rocky crevices along mountain path, 44°46'44.26"N, 14°55'55.9"E, c. 800 m, 13 Sep 2023, S. Bogdanović & V. Lopac s.n. (ZAGR 78944!; isotypes: B!, BUNS!, CAT!, ZA!, ZAGR!).

– Allium fuscum var. gracile Anačkov, Takson. Horol. Roda Allium Srbiji : 132. 2009, nom. inval., not effectively published ( Turland & al. 2018: Art. 30.9 and 32.1(a)).

Diagnosis — Allium dinaricum is similar to A. fuscum but differs from the latter in having outer bulb tunics slightly fibrous (vs coriaceous), stems often geminate (vs single), leaf cross-section semi-circular (vs flat), leaf blade narrower, with 2 prominent ribs, spathe valves usually shorter and erect (vs longer and divaricate or reflexed), inflorescence few-flowered (vs many-flowered), tepals smaller, outer stamen filaments shorter, annulus shorter, anther apex apiculate (vs rounded), and ovary smaller.

Description — Bulb ovoid to ovoid-subglobose, 8–20 × 6–14 mm, sometimes with some bulbils at base of stem; outer tunics slightly fibrous, greyish brown, inner ones membranaceous, whitish. Stem 15–40 cm tall, cylindric, glabrous, erect, covered by leaf sheaths for 1/3–1/2 of total length, often with 2 stems, one inserted externally to bulb, and second one in centre of leaf sheaths. Leaves 3–5, green, glabrous, with blade rigid, semi-cylindric, compact or slightly fistulous, with 2 prominent ribs, 7–25 cm × 1.5–2.5 mm. Spathe persistent, with two valves unequal, opposite, erect to slightly divergent at flowering and often divaricate at fruiting, much longer than inflorescence, larger 7-nerved and 4–16 cm long, smaller 5- or 6-nerved and 2–6 cm long. Inflorescence lax and hemispherical, 10–30(–45)-flowered; pedicels erect or curved, unequal, 7–25 mm long. Perigone campanulate, with tepals equal, greenish yellow tinged with purplish brown, elliptic, rounded at apex, 4.5–5.5 × 2–2.4 mm, midrib purplish green. Stamens included in perigone or slightly exserted, with simple filament, white or pinkish, unequal, outer ones 1.5–2.4 mm long, inner ones 2–4 mm long, connate below into an annulus 1–1.2 mm high; anthers white to straw-coloured, oblong, c. 1.2 × 0.7 mm, slightly apiculate at apex. Ovary cylindric, greenish yellow, minutely tuberculate above, 3–3.5 × 1.7–2 mm; style white, 0.7–2.2 mm long. Capsule 3-valved, obovoid, green 4–5 × c. 4 mm.

Phenology — The flowering period of Allium dinaricum starts in late July and extends until mid-October, while fruiting is completed in October and November.

Distribution and ecology — Based on field surveys and herbarium investigation, Allium dinaricum is distributed across several Balkan countries: Croatia, Bosnia and Herzegovina, Serbia and Montenegro ( Fig. 2). It usually grows in rupestrian habitats, primarily on carbonate substrates, occasionally on siliceous and serpentinites rocks. Usually, this species inhabits shaded rock crevices within woodlands, especially in coastal and hilly regions, and also on sunny rocky outcrops in mountainous areas up to an elevation of 1400 m ( Fig. 3A, C). In Croatia, A. dinaricum is accompanied by many other chasmophytes, many of which are often endemic, such as Allium horvatii Lovrić , Asperula scutellaris Vis. , Astragalus muelleri Steud. & Hochst. , Campanula fenestrellata subsp. istriaca (Feer) Damboldt , Campanula pyramidalis L., Centaurea dalmatica A. Kern. , Centaurea spinosociliata Seenus , Inula verbascifolia Poir. , Iris illyrica Tomm. ex Vis. , Micromeria croatica Schott , Satureja subspicata Bartl. ex Vis. , Seseli tomentosum Vis. and Sesleria juncifolia Suffren. In Serbia and Montenegro, A. dinaricum grows together with other endemics, among them Allium serbicum Vis. & Pančić , Bupleurum karglii Vis. , Campanula secundiflora Vis. & Pančić , Centaurea derventana Vis. & Pančić , Euphorbia spinosa subsp. glabriflora (Vis.) Frajman , Linaria rubioides Vis. & Pančić , Ramonda serbica Pančić , Reichardia macrophylla Vis. & Pančić , Silene serbica Adam. & Vierh. and Stachys anisochila Vis. & Pančić. Overall , A. dinaricum is ecologically well differentiated from the other species within A. sect. Codonoprasum , especially those with autumnal flowering pattern. Allium dinaricum is an obligate chasmophyte, growing almost exclusively on rock faces, whereas the other taxa usually grow in meadows, shrublands, underwood and in salt marshes.

Etymology — The specific epithet refers to the Dinaric Alps, where the new species is distributed.

Leaf anatomy — The leaf cross-section of Allium dinaricum exhibits a semi-circular outline, characterized by two prominent ribs in the abaxial surface. The epidermis consists of small cells covered by a thin cuticle, with numerous stomata distributed along the whole leaf surface. The palisade tissue is regular and compact, forming a single external layer with larger cells, while a second layer with smaller cells is present only in the adaxial surface. The spongy tissue is compact in the peripheral part and/ or slightly fistulous, constituted by small cells, while it is rather lax in the central part, therefore the mesophyll appears slightly fistulous. Many secretor canals occur beneath the palisade tissue. The vascular bundles are 16 (in the largest leaves), consisting of 13 variable-sized bundles in the adaxial surface, with only 3 small-sized bundles in the abaxial surface ( Fig. 4).

Seed morphology and microsculpturing — According to the literature data ( Fritsch & al. 2006; Neshati & Fritsch 2009; Celep & al. 2012; Salmeri & al. 2016; Lin & Tan 2017), the microsculpturing of the seed testa in Allium is a conservative and stable character, which provides relevant information regarding the taxonomic treatment of this genus. The seeds of A. dinaricum are semi-ovoid in outline (3.8–4 × 2–2.1 mm), with a weakly rugose surface ( Fig. 5A, B). Observations under SEM at high magnification (500× and 1000×) show irregularly polygonate testa cells, 28–65 μm in diam. ( Fig. 5C–F). The anticlinal walls appear flat, straight to curved, and are covered by raised strap-like sculptures forming a widened intercellular region. The anticlinal walls of the seedbed are characterized by a long connection in the form of the Ω-S connection model according to Fritsch & al. (2006). A similar form of undulation is also present in A. fuscum and other possibly related species ( Anačkov 2009). The periclinal walls are slightly raised, with several granulose verrucae; the central is larger, accompanied by smaller and irregularly shaped verrucae distributed along the cell edges. These micromorphological seed ornamentations closely resemble those observed in other species of A. sect. Codonoprasum ( Češmedžiev & Terzijski 1997; Neshati & Fritsch 2009; Celep & al. 2012; Brullo & al. 2013; Salmeri & al. 2016; Özhatay & al. 2018).

Karyology — Allium dinaricum has a diploid chromosome complement with 2 n = 16 ( Fig. 6A). The karyotype ( Fig. 6B) is regular, composed mainly of metacentric (m) chromosomes, with only three pairs slightly asymmetric and belonging to the meta–submetacentric (msm) type ( Tzanoudakis 1983). One msm chromosome pair is microsatellited on the short arm. The karyotype formula can be resumed as 2 n = 2 x = 16: 10 m + 4 msm + 2 msmsat. Absolute chromosome length ranges from 11.7 ± 1.5 μm for the longest chromosome to 8.6 ± 1 μm for the shortest, while the relative length varies from 7.4 ± 0.2 % to 5.45 ± 0.3%. Chromosome measures and symmetry indices ( Table 2) indicate a high degree of homogeneity and symmetry of the A. dinaricum karyotype.