Limonium rhodense M.B. Crespo & Pena-Martín, 2013

Crespo, Manuel B. & Pena-Martín, Carolina, 2013, Two new species of Limonium (Plumbaginaceae) from Rhodes Island (eastern Aegean area, Greece), Phytotaxa 94 (2), pp. 30-40 : 35-38

Limonium rhodense M.B. Crespo & Pena-Martín , sp. nov.

Type :— GREECE. Dodecanese Islands, Rhodes, between Mandriko and Kalavardha, S of Kamiros , 36º19’21”N, 27º52’42”E (UTM: 35SNA788200), in low maritime cliffs, 3 m a.s.l., 10 September 2011, Crespo & Pena-Martín s.n. (holotype ABH!)

( Figs. 4 , 5 A–F ).

Diagnosis: — Species notabilis ad Limonium roridum et L. ammophilonem affinis sed eis multo discrepat. A priore insuper spiculis dense pilosis, superioribus bracteis spicularum longioribus, et ramis sterilibus nullis vel solum 1–2 facile distinguitur. A posteriore insuper differt foliis densioribus dispositis et magis numerosis, fere omnibus per anthesin viridibus; caulibus valde tuberculato-asperis, tuberculis majoribus densioribusque, ramis sterilibus nullis vel 1–2 brevioribus a basi munitis; bractea superiore angustiora (3–4 mm lata); costis calycum supra basin dentium desinentibus et post anthesin limbo non vel brevissime lacerato, lobis non curvatis. Ab L. subg. Limonium pertinent.

Description: —Perennial plant, 10–35 cm tall, with many or few stems, very rough, densely covered with large whitish crateriform tubercles which are depressed in the central part. Caudicles 3–10 cm long, densely branched with many short branches, and densely leafy in the upper part. Most leaves of the rosette green during the anthesis phase, only lowermost ones brownish and persistent after withering, (10–)20–35(–40) × 2– 5 mm, mostly oblanceolate to subspathulate, obtuse, shortly awned (awn up to 0.2 mm long), with margins sinuose-crenate (because of abundant tubercles), 1-nerved, tapering into a long petiole 1–2 mm wide, 1/2–3/4 as long as the blade. Lower cauline leaves scale-like, dark brown, 2–3 mm long, triangular-acuminate. Stems stout, (5–) 10–25 cm long, erect, branched almost from the base. Branches distichously arranged, numerous, up to 5 cm long, erect-patent to subarched, with short secondary branchlets, sometimes proliferous (with small leaf rosettes), all fertile or rarely 1–2-lowermost sterile and shorter. Inflorescence paniculate, subarticulate, obtrullate or rhombic in shape, rarely subsecund. Spikes 15–30 mm long, commonly secund. Spikelets 8–10 mm long, hairy (hairs 0.2–0.5 mm long), 3–4(–5)-flowered, in groups of 2–3 per cm. Outer bract densely hairy, 1–2.2 × 1–2 mm, broadly triangular-ovate, dark brown, acute, acuminate in the middle part, with a narrow membranous margin including the acumen. Middle bract sparsely hairy at the base and on ribs, 2.5–3.0 × 2.0– 2.5 mm, oblong, hyaline-membranous. Inner bract densely hairy, 7–8 × 3–4.3 mm, broadly elliptic-obovate, green with brownish margin, shortly acuminate in the middle part (acumen up to 0.2 mm long), with a narrow margin (0.2–0.4 mm) including the acumen. Calyx 5.5–7 mm long, exceeding inner bract about 1–2 mm; tube hairy all around, mostly on ribs, with long and sparse hairs; limb as long as the tube or a little shorter, not or very slightly lacerate after anthesis with lobes not curved; teeth about 0.5 mm long, broadly semielliptic; tube ribs ending above the teeth base. Corolla infundibuliform, 3.5–4.5 mm in diameter. Petals 6–8 × 1.5–2 mm, cuneate, emarginate at the apex, pale violet. Stigmata filiform, covered with long, conical papillae [type “papillate” according to Baker (1948, 1953)]. Pollen grains very narrowly reticulate [type “B” according to Baker (1948, 1953)].

Etymology:—The epithet rhodense refers to the island of Rhodes.

Ecology and distribution:— Limonium rhodense grows on gravely soils and crevices of low maritime cliffs, also in a first-line topographical position enduring very stressful conditions, due to the combined effect of the abrasive wind and the spray of sea water. Flowering from July to September; fruiting from August to October. The species is only known from the coast line between Mandriko and Kalavardha, in the western part of Rhodes Island, Greece, and it can be considered endemic ( Fig. 3 ).

Breeding system:—The analysis of pollen-stigma combinations showed that L. rhodense is monomorphic. Contrarily to L. quinnii , the only found combination was ‘ type B’, with ‘B’ pollen grains and ‘papillate’ stigmata, which is also a self-incompatible one ( Baker 1948, 1953; Erben 1978, 1979). As in the latter species, this breeding system together with an abundant seed-set in wild populations, indicates that L. rhodense most probably is also apomictic.

Taxonomical notes:— Limonium rhodense can be included in subgenus Limonium (sensu Lledó et al. 2005) and particularly in the L. palmare aggregate (sensu Greuter et al. 1989: 335–336), which is easily distinguished by the presence of whitish crateriform tubercules on leaves and stems, and the production of small leaf rosetes in the axil of lower branches. This new species is closely related to L. ammophilon . Both taxa are clearly recognized by the densely hairy bracts, a diagnostic character not found in the rest of representatives of the L. palmare aggregate ( Papatsou & Phitos 1975), namely in L. roridum ( Sibthorp & Smith 1821: 91) Brullo & Guarino (2000: 267) , a morphologically close allied widely distributed in the eastern Aegean area which has been usually included in L. graecum ( Poiret 1817: 237) Kuntze (1891: 395) , but which deserves recognition at the species rank ( Brullo & Guarino 2000). However, remarkable distinctive characters are found in L. rhodense , mostly concerning the general habit and spikelet characteristics that allow differentiation from L. ammophilon ( Table 1 ). Stems are more densely and long branched, and the sterile branches are completely lacking or are reduced to 1–2 short branchlets at the base of the inflorescence, they all being more densely covered with larger crateriform tubercles that give a strongly rough touch and appearance. Leaves are mostly green at the anthesis and they are more numerous and very densely disposed at the top of shorter caudicles, which produce more compact, shorter and broader rosettes. The inner bract is usually narrower, and the calyx limb is sometimes very weakly lacerate after anthesis, with lobes not curved ( Figs. 4– 5 ). It is important to note, however, that contrarily to data shown in the protologue ( Papatsou & Phitos 1975), leaves in both L. rhodense and L. ammophilon seem to be mostly oblanceolate to subspathulate, obtuse and shortly mucronate, they being not always linear-lanceolate, as can be deduced from type material of the latter (preserved in UPA and E). Nevertheless, in L. rhodense they are broader and lack a prominent keel beneath.

Additional specimen examined:— GREECE. Dodecanese Islands, Rhodes, between Mandriko and Kalavardha, S of Kamiros , 36º19’21”N, 27º52’42”E (UTM: 35SNA788200), in low maritime cliffs, 3 m a.s.l., 10 September 2011, Crespo & Pena-Martín s.n. (isotypes: ABH! num. 68188, MA!) .

Figures

FIGURE 3. Distribution map of Limonium quinnii M.B. Crespo & Pena-Martín (circle) and L. rhodense M.B. Crespo & Pena-Martín (square) in Rhodes Island (Greece).

FIGURE 4. Holotype of Limonium rhodense M.B. Crespo & Pena-Martín (ABH58286).

FIGURE 5. Limonium rhodense M.B. Crespo & Pena-Martín. A. Detail of a rosette leaf. B. Spike with spikelets. C. Outer bract. D. Middle bract. E. Inner bract. F. Calyx. G. Detail of the calyx limb showing the ending ribs. Scale bars: A–B, 5 mm; C–F, 1 mm (drawings by C. Pena-Martín).