Limonium irtaensis P.P.Ferrer, A.Navarro, P.Pérez, R.Roselló, Rosselló, M.Rosato & E.Laguna, 2015

Ferrer-Gallego, P. P., Navarro, A., Pérez, P., Roselló, R., Rosselló, J. A., Rosato, M. & Laguna, E., 2015, A new polyploid species of Limonium (Plumbaginaceae) from the Western Mediterranean basin, Phytotaxa 234 (3), pp. 263-270 : 264-266

Limonium irtaensis P.P.Ferrer, A.Navarro, P.Pérez, R.Roselló, Rosselló, M.Rosato & E.Laguna , sp. nov. ( Figs. 1 – 4 , Table 1 )

Type:— SPAIN. Castellón: Peñíscola, Sierra de Irta, Cerromar , 31SBC5695, 5 m, 29 July 2012, cliffs and coastal rocky outcrops, Navarro, Rosselló, Pérez & Laguna 013001 (holotype VAL-226810 ! , isotype BC-879803 ! ).

Diagnosis: — Planta perennis 40–60(–70) cm alt., glabra, paucicaulis, foliis ovatis–spatulatis orbiculatis, obtusis et apiculatis, inflorescentia triangulatis–lanceolatis et non ramulis sterilis, spiculis (8–) 10–20 mm longis, bractea inferiore 0.9–1.0 × 1.0 mm longa, bractea media 1.0–1.3 × 0.9 mm longa, bractea superiore 3.0–3.2 × 1.9–3. 2 mm longa, calyce 3.6–4.2 mm, calyce ex bractea superiore 1.0– 1.6 mm exserto, petalo violaceo 7.2–7.5 × 2.4–2.5 mm, semina 1.5 × 0.5 mm. Combinatione pollen/stigma “B/papillate”. Chromosomatum numerum 2n=26.

Description: —Perennial plant 40–60(–70) cm tall, with 1(–3) stems, glabrous, caudice thick and woody. Stem (20–) 25–45 cm long, smooth, erect, straight, glabrous, 1.3–1.5 mm thick. Branching starts from the lower third of the total length of the stem. Basal leaves (3–)4–7(–9) × (0.5–)0.7–1.7(–2.5) cm, the upper ones green at anthesis, sometimes withered, the lower ones withered and persistent. Leaf margin ovate-spathulate to orbicular-elliptic, green, surface slightly rough with numerous papillae; marked and visible midrib to the apex of the leaf, 2–3 lateral nerves also visible but slenderer and less marked, reaching the upper third of the blade; apex obtuse to subobtuse; mucro (apiculum) quite visible, up to 2 mm; membranous margin, 0.1 mm; petiole up to 1.2–2.2 mm wide (½‒¾ the length of the blade). Inflorescence (10–) 15–30 cm long, open or with spikelets loosely arranged; shape type C (according to the forms indicated by Erben 1993), triangular-lanceolate, without sterile branches. Spikes (8–) 10–20 mm, loose, straight or slightly arched downwards, erect-patent. Spikelets 1–2(–3) flowered, 4–6 mm long, 3–6 per cm; outer bract 0.9–1.0 × 1.0 mm, ovate to subcircular, blunt and obtuse apex, wide membranous margin; fleshy inner part and apex nearly reaching (occasionally reaching) the upper margin; middle bract 1.1–1.3 × 0.9 mm, oblong, membranous, emarginated; inner bract 3.0–3.2 × 1.9–3.2 mm, obovate to orbicular (occasionally even wider than longer), with blunt to rounded apex; margin widely membranous, central part 2.5 × 1.9–2.0 mm, fleshy, oblong-elliptical, with broad chestnut-coloured margin and apex 0.2–0.4 mm, not reaching the margin. Flowers 3–5 mm diameter; calyx 3.6–4.2 mm, surpassing 1.0– 1.6 mm the inner bract; tube covered with hairs in all sides except in one of them, hairs densely arranged in one side, teeth 0.4–0.5 × 0.6–0.7 mm, widely triangular-ovate, obtuse; tube ribs not reaching the base of the teeth; petals 7.0–7.5 × 1.8–2.5 mm, emarginated, cuneiforms, violet; stigma papillate. Pollen showing a fine reticulum and narrow mesh, B type. Fruit 1.5 × 0.5 mm.

Etymology: —The specific epithet refers to the locus classicus, Irta mountains ( Spain).

Phenology: —Flowering time: June‒September. Fruiting time: July‒October.

Chromosome number: —2 n = 26.

Taxonomic remarks: — Limonium irtaensis is closely related to the polyploid species L. perplexum , L. virgatum , L. thiniense , and to some members of the L. delicatulum (Girard 1844: 327) Kuntze (1891: 395) complex.

On the basis of the cytogenetic grounds, the new species shows the same chromosome number of L. thiniense only, while L. delicatulum has 2 n = 25 and L. perplexum , and L. virgatum have 2 n = 27. According to Palacios et al. (2000) the 2 n = 25, 2 n = 26 and 2 n = 27 chromosome complements did not arise by aneuploidy events in Limonium , but from a contrasting hybrid origin involving reduced and unreduced x =8 and x = 9 gametes. Thus, the origin of the new species should be traced from ancient hybridogenic processes (diploids with 2 n = 16 and 2 n = 18 are absent from the area where L. irtaensis occurs) or from anagenetic events involving 2 n = 26 ancestors. However, no closely related species having 2 n =26 chromosomes has been identified. Morphological features from the related L. thiniense , L. girardianum and L. gibertii (Sennen 192 3: 113) Sennen (1936: 271) (all with 2n = 26 chromosomes) did not support a progenitor-derivative origin from any of these species.

From the morphological point of view, L. irtaensis can be distinguished from the related species by 1) its orbicular elliptical leaves, always green at anthesis, and with an obtuse apex, tapering in a long and conspicuous apiculum, and 2) a different inflorescence shape (type C), triangular–lanceolate, with first order branches up to 15 cm long, forming an angle of 50º–90º ( Table 1 ). On the other hand, Limonium irtaensis is morphologically close to L. delicatulum , an endemic species from south-eastern Spain. The aggregate of L. delicatulum is highly diversified in the western Mediterranean region and specifically in the Iberian Peninsula ( Erben 1993; Palacios et al. 2000; Lledó et al. 2005). Limonium irtaensis can be distinguished from L. delicatulum by the inflorescence type and its smaller size, as well as by the outer, middle and inner bracts which are always less. Therefore, both morphological and cytogenetical differences allows recognition of L. irtaensis at specific rank ( Table 1 ).

Distribution, habitat and ecology: — Limonium irtaensis was found for the first time in July 2012, at Cerromar cliffs (Peñíscola), about 200 m northward to the site where specimens attributed to L. perplexum were formerly recorded (F. Royo, pers. comm.). It grows on an outcrop of calcareous conglomerate belonging to the Quaternary alluvian fans of gravels and clays ( IGME 1973) rich in fossils and finely angulated gravels.

Conservation status: —During field investigations (2013‒2014), a total of 19 individuals of Limonium irtaensis were found. Furthermore, a new growing site with 3 specimens was found in 2013 in Cala Ordí (Peñíscola), growing on a similar geological substrate but less rich in gravels. Taking into account the very scarce number of specimens and populations, both located a few meters from buildings or roads, the species is here classified as “Critically Endangered” (CR) according to IUCN Red List Category and Criteria (2001, 2011). According to the Valencian threatened species list provided by Aguilella et al. (2009), it should be added to the Valencian vascular species facing an extremely high risk of extinction. It should also be listed at first place according to the absolute Valencian endemism. In order to ensure its surviving, the Centre for Applied Forest Research (CIEF) started in 2012 a recovery programme for this species through the propagation by seeds in order to obtain new seeds/plants for its conservation in the Germplasm Bank at the CIEF.

Figures

FIGURE 1. Habitus of Limonium irtaensis.

FIGURE 2. Limonium irtaensis: (a) spikes; (b) leaves; (c–d) outer bract, adaxial and abaxial surfaces; (e) middle bract; (f) inner bract; (g–h) calyx; (i) fruit. Voucher: A. Navarro, J.A. Rosselló, P. Pérez Rovira & E. Laguna 013001 (Castellón: Peñíscola, Sierra de Irta, 31SBC5695, Castellón, Spain, VAL-226810, holotype). Illustration by Roberto Roselló.

FIGURE 3. Distribution map of Limonium irtaensis; natural plant in the Irta mountains.

FIGURE 4. Somatic metaphase plate of Limonium irtaensis. Scale bar 5 μm.