Limonium poimenum Ilardi, Brullo, Cusimano & Giusso, 2014

Ilardi, Vincenzo, Brullo, Salvatore, Cusimano, Dario & Galdo, Gianpietro Giusso Del, 2014, Limonium poimenum (Plumbaginaceae), a new chasmophyte species from Sicily, Phytotaxa 188 (5), pp. 268-274 : 268-273

Limonium poimenum Ilardi, Brullo, Cusimano & Giusso sp. nov. ( Figs. 1 , 2A–C )

Type:— ITALY. Sicily: Monte Pecoraro presso Palermo , versante occidentale, a ca. 700 m di quota, 39° 09′ 48′′ N, 13° 07′ 22′′ E, 11 July 2014, Ilardi & Cusimano s.n. (holotype CAT!; isotypes: CAT!, PAL!)

Diagnosis: — Recedit ab Limonio todaroano habito dense pulvinato, foliis viridibus, 1-nerviis, 10–50 cm longis, 3–8 mm latis, rotundatis vel subobtusis, leviter revolutis margine, scapis rugoso-striatis, ramis sterilibus simplicibus aliquot, spicis 5–20 mm longis, spiculis 5–6 mm longis, 2-floris, ad 6–7 in 1 centimetro dispositis, bractea inferiore 2–2.5 × 1.5–2 mm, bractea media denticulata apice, bractea superiore apiculo centrali attingens marginem superiorem, calyce 4–4.5 mm longo, ex bractea superiore 1.5–1.8 mm exserto, tubo unilateraliter dense piloso et lobis triangularibus.

Description: —Plant perennial, glabrous, forming a sub-shrub densely pulvinate, 30–50 cm tall, with several erect stems and a very robust tap-root. Caudices 10–20 cm long, branched, densely spirally leafy mainly in the upper half, living leaves in apical rosettes. Leaves fleshy, green, slightly rugose, 10–50 mm long and 3–8 mm wide, oblanceolatespathulate, rounded to subobtuse at apex, slightly revolute at margin, uninerved, gradually tapering into the petiole. Stems green, rugose-striate, 12–35 cm long, slightly flexuous, often branched from the base, with several simplex sterile branches, 0.5–5.0 cm long. Inflorescence terminal, few branched, with branches sub-erect, the lower long pedicelled, the upper with pedicel progressively reduced. Spikes 5–20 mm long, straight to slightly curved, erect to directed obliquely upwards; axis of spike rugose. Spikelets 5–6 mm long, 2-flowered, densely arranged, 6–7 per 1 cm. Outer bract 2.0– 2.5 mm long and 1.5–2.0 mm wide at the base, triangular-ovate, acute, with margin broadly membranous and central part fleshy, acuminate up to the apex. Middle bract membranous, 2.0–2.2 × 1.1–1.3 mm, oblong-elliptic, rounded-denticulate at the apex. Inner bract 4.2–5.0 × 2.5–2.7 mm, oblong, rounded, with margin more or less broadly membranous, central part fleshy, lanceolate, acuminate, forming a narrowly triangular tip, 1.0– 1.2 mm long, reaching the upper margin. Calyx 4.0– 4.5 mm long, exceeding the inner bract by 1.5–1.8 mm, with tube densely hairy only from one side and 5 ribs ending at the base of lobes; calyx lobes triangular, 0.6–0.8 × 0.6–0.8 mm. Corolla pale violet.

Chromosome number: —Unknown.

Etymology: —The specific epithet is derived from the ancient Greek “poimen”, which means shepherd. It refers to “Monte Pecoraro” (in English Mt. Shepherd), the locus classicus of L. poimenum .

Phenology: —Flowering July−August, fruiting up to October.

Habitat and distribution —It is a rare endemic chasmophyte restricted to the calcareous cliff facing the airport of Palermo near Punta Raisi (NW Sicily, Fig. 3 ). This new species grows in the crevices of more or less vertical surfaces at an elevation of 650−750 m a.s.l. The cliff has a western aspect, and is usually affected by a regime of dense fog due to the humid winds coming from the Tyrrhenian Sea. L. poimenum is a member of a rupestrian plant community characterized by numerous endemics linked to these habitats, such as Centaurea panormitana Lojacono (1903: 137) , Helichrysum panormitanum Tineo ex Gussone (1844: 467) subsp. panormitanum , Lomelosia cretica ( Linnaeus 1753: 100) Greuter & Burdet (1985: 74) , Seseli bocconei Gussone (1821: 80) , Dianthus rupicola Bivona (1806: 31) subsp. rupicola , Iberis semperflorens Linnaeus (1753:648) .

Conservation status: —According to the IUCN Red list category and criteria ( IUCN 2014), Limonium poimenum should be treated as Endangered: EN (criterion D), because of the low number of individuals (less than 100) and the very limited distribution (less than 1 km 2).

Taxonomical notes: — Limonium poimenum belongs to the subgenus Limonium and it is morphologically well different from other species by a pool of diacritical characters: the dense shrubby pulvinate habit, few branched and poor inflorescence, leaves densely arranged along the caudices, dense and very short spikes. Among the Limonium occurring in Sicily, this new species shows some relationships mostly with L. todaroanum , which grows at Mt. Passo del Lupo (San Vito Lo Capo, NW Sicily) not far from Mt. Pecoraro ( Fig. 3 ). L. todaroanm also grows in the crevices of a calcareous cliff of a mountain near Trapani at a elevation of about 700 m a.s.l., together with several other endemic chasmophytes. Despite this L. todaroanum clearly differs from L. poimenum in having a habit lax not pulvinate, leaves dark green, (1–)3-nerved, obtuse (rarely rounded or retuse), (20–)30–70 × 7–12 mm, flat, stems slightly scabrous, sterile branches absent o rare, spikes longer and lax, 2–6 cm long, with 2–4(–5) spikelets per 1 cm, spikelets (2–)3- lowered, 7–8 mm long, outer bract 1.5–2 × 1.3–1.5 mm, middle bract smooth at the apex, inner bract with central tip 0.9–1.0 mm long, not reaching the upper margin; calyx 5–7 mm long, exceeding the inner bract by 2–3 mm, with tube sparsely hairy at the base and lobes subrounded ( Figs. 2D , 4 ). Besides, both species behave as true chasmophytes linked to unsalted substrates and growing in mountain stands. For their peculiar morphological features, unusual ecological requirements, isolated and well circumscribed distribution, as well as for the low number of individuals, these two species must be considered as relicts, similarly to many other rupestrian species occurring in this habitat.

Figures

FIGURE 1. Diagnostic features of Limonium poimenum. A. Habit. B. Leaves. C. Inflorescence. D. Spikelet. E. Outer bracts. F. Middle bracts. G. Inner bracts (dorsal view). H. Inner bract (lateral view). I. Calyx. J. Calyx teeth. Illustration by S. Brullo based on living material coming from the type locality (CAT).

FIGURE 2. Phenological features of Limonium poimenum and L. todaroanum. A. Rupestrian habitat of L. poimenum (Monte Pecoraro). B. Habit of L. poimenum. C. Inflorescence of L. poimenum. D. Inflorescence of L. todaroanum. (A–C: photos by V. Ilardi, D: photo by S. Brullo).

FIGURE 3. Geographical distribution of Limonium poimenum (circle) and L. todaroanum (square).

FIGURE 4. Diagnostic features of Limonium todaroanum. A. Habit. B. Leaves. C. Inflorescence. D. Spikelet. E. Outer bracts. F. Middle bracts. G. Inner bract (dorsal view). H. Inner bract (lateral view). I. Calyx. J. Calyx teeth. Illustration by S. Brullo based on living material coming from Mt. Passo del Lupo (type locality, CAT).