Hieracium racemosum subsp. spinidentatum Gottschl. & M.Villa, 2022

Gottschlich, Günter & Villa, Milena, 2022, Hieracium racemosum subsp. spinidentatum (Asteraceae), a new hawkweed from Lombardy, Italy, Phytotaxa 531 (1), pp. 78-82 : 78-82

Hieracium racemosum subsp. spinidentatum Gottschl. & M.Villa , subsp. nov. ( Figs. 1–3 ).

Type:— ITALY. Lombardy: province of Lecco, Parco Regionale di Montevecchia e della Valle del Curone, Missaglia , Via Montevecchia , 450 m s. m. (45.724637° N, 9.351219° E), 14.8.2021, M. Villa (holotype FI!; isotypes MSMN, Hb. Gottschlich 78583) .

Diagnosis:— Margine foliorum propter dentes spinosiformes Hieracio racemoso subsp. leiopsi similia sed folia caulina angustiora basin versus longe petioliformiter contracta, involucri phyllis pilis glanduliferis luteis modice densis obsitis differt.

Perennial, hemicryptophyte. Rhizome stout, vertical. Stem erect, vertical, cylindrical, stout (3–5 mm in diam.), 80– 110 cm tall, dark to reddish green, striated, aphyllopodous, with moderate to subdense, 2–3 mm long, whitish, soft, dentate simple hairs and sparse to moderate stellate hairs. Cauline leaves 20–30, the lower ones 15–18(–20) cm long and 4–5 cm wide, with a winged petiole 2–3 cm long, ovate-lanceolate, margin spine-like dentate especially in the lower part, dark green, lower surface sometimes slightly reddish green, glabrous or with a few whitish, soft, dentate simple hairs 1 mm long, leaf vein of the lower surface with moderate to subdense white simple hairs 1–2 mm long, gradually decreasing in size upwards, the upper cauline leaves only 3–5 cm long and 0.5–1 cm wide, denticulate, sessile. Inflorescence paniculate, branches 10–15(–20), straight or laxly curved, 4–10(–15) cm long, each with 1–3(–5) capitula; capitula (10–)15–25(–30); acladium 1–2 cm long. Peduncles with 3–5 linear, light green bracts near the capitulum, with sparse white simple hairs 1–1.5 mm long, a few yellow glandular hairs 1 mm long and dense stellate hairs. Involucre almost ovoid, 9–10 mm long. Involucral bracts in a few series, light to olive green, linear-lanceolate, 1.2–1.5 mm wide, subacute, with moderate glandular simple hairs 0.2–0.4 mm long with yellow glands on white peduncles, few simple and few stellate hairs. Corolla limb ligulate, yellow, glabrous. Styles yellow with black papillae. Margins of alveoli with short broad teeth. Achenes 3.5–4 mm long, reddish-brown.

Etymology:—The epithet spinidentatus refers to the conspicuous spike-like perforation of the leaf margins.

Phenology: —Flowering August to September. Fruiting September to October.

Distribution and ecology:—The new taxon was found in a single locality, with a few individuals (15–20), a few meters away from each other.

The plants grow on a pre-quaternary outcrop made up of sedimentary rocks from the Cretaceous-Eocene. The sediments were formed on the seabed, mainly due to turbid currents (flysch or turbidites) and are made up of sandstones, pelites and marls that take on horizontal, oblique and vertical geometries with a thickness varying from a few centimeters to one meter.

Conservation status:—The new taxon is currently known only from one restricted locality covering about 80– 100 m 2. The upper part of the rocky outcrop (about 4–5 m high) is currently covered with a vegetation that could hide or suffocate other plants. It is therefore necessary to study conservation and reinforcement actions for the plants present today.

Furthermore, monitoring and research actions are needed to better understand the real population size and demographic trends of the taxon in similar environments of the Park.

Taxonomic relationship:—In respect of the spike-like dentate leaf margin, H. racemosum subsp. spinidentatum resembles H. racemosum subsp. leiopsis Murr & Zahn in Koch (1902: 1927), but its leaves are narrower and long constricted into an indistinct petiole or into the base. Also there are differences in the indumentum: the phyllaries of H. racemosum subsp. leiopsis are nearly glabrous, whereas the phyllaries of H. racemosum subsp. spinidentatum bear a moderate amount of glandular hairs and some few simple and stellate hairs.

Other specimen examined (paratype): — ITALY. Lombardy: Parco Regionale di Montevecchia e della Valle del Curone, Panoramica , 450 m s. m. (45.724517°N, 9.351200°E), 4/8/2021 and 27.8.2014, M. Villa ( Hb. Parco di Montevecchia e della Valle del Curone) .

Acknowledgements: —The authors would like to thank Dott. Gabriele Galasso and Dott. Enrico Banfi of the Natural History Museum of Milan for their constant collaboration and valuable suggestions.

Special thanks go to Giuseppe Sardi (member of the board of the Park) for his support and practical help in the field research.

The authors warmly thank Dr. Alexander Sennikov for helpful comments to the manuscript.

Figures

FIGURE 1. Hieracium racemosum subsp. spinidentatum: holotype (FI).

FIGURE 2. Hieracium racemosum subsp. spinidentatum: single capitulum.

FIGURE 3. Hieracium racemosum subsp. spinidentatum: indumentum of the stem and leaves.