ALLIUM OPORINANTHUM (ALUACEAE), A NEW SPECIES FROM THE NW MEDITERRANEAN ÁREA

BRULLO, S.. P. PAVONE & C. SALMERI (1997). Allium oporinanthum (Alliaceae), a new species from the NW Mediterranean área. Anales Jard. Bot. Madrid 55(2): 297-302. A new species Allium oporinanthum is described from some localities of the NW Mediterranean área. The new species belongs to A. sect. Codonoprasum and is usually localized on limestone in shady rocky places. It is an autumnal species with a tetraploid chromosome number (2n = 32). Its old origin and its taxonomic relationships are examined too.


INTRODUCTION
In the context of cytotaxonomic research on the populations belonging to Allium sect.Codonoprasum Reichenb, in the Mediterranean área, a very interesting autumnflowering taxon has been found.

HABITAT AND DISTRIBUTION
Allium oporinanthum grows, together with other chasmophytes, on calcareous shady rocks or, more rarely, in semirupestrian places where it is a member of garigues.It occurs in some localities of the NW Mediterranean área, extending from Denia near Valencia to Saint Tropez near Toulon (fig.2).Its populations are small, isolated and very localized, which gives support to a relictual character of this taxon at present.

KARYOLOGY
The karyological investigation was carried out on living material coming from Cap de Sant Antoni (Denia), Montserrat (Barcelona) and Saint Baume (Marseille).Bulb root tips were pre-treated with 0.3 % colchicine, fixed in Carnoy and stained using the Feulgen method.
All the examined populations of Allium oporinanthum have a tetraploid chromosome complement with 2n = 32 (fig.3).The karyotype analysis revealed that it is arranged in pairs instead of four chromosome sets.
The chromosome nomenclature follows LEVAN & al. (1964).Specifically, there are 15 metacentric pairs, the smallest of which is always macrosatellited on the short arm, and by one submetacentric macrosatellited pair; some metaphasic plates show 2-4 pairs microsatellited on the short arm or macrosatellited on the long arm too (fig.4).This variance in the number of satellites may be due to the squashing technique, sometimes unable to reveal them.
On the whole, the chromosome complement of A. oporinanthum is quite homogeneous and symmetrical.This is also confirmed by computing the asymmetry degrees proposed by STEBBINS (1971), from which the karyotype of A. oporinanthum falls within the type 2A, as the difference between the largest and the smallest chromosomes is < 2:1 and the proportion of chromosomes with an arm ratio < 2 ranges from 0.06 to 0.12.

LEAF ANATOMY
The histological study of the Allium oporinanthum leaves was made on living material from Cap de Sant Antoni (Denia) and Saint Baume (Marseille); the transversal sections were fixed in Karpetschenko, embedded in paraffin and stained with ruthenium-red and yellowish-lightgreen.
The leaves have a semicylindrical outline and many ribs.The epidermis has bigger cells on the top of the ribs and is covered by a well developed cuticle.The stomata are distributed on the whole surface.The palisade tissue is regular and onelayered with cylindrical cells.The spongy tissue is compact with bigger cells in the centre; in the peripheral portion there are several secretory cañáis and 9-14 vascular bundles, 4-7 of which are adaxial (fig.5).

TAXONOMIC RELATTONSHIPS
The occurrence of a two-valved spathe longer than the inflorescence, simple stamens and ovary with inconspicuous nectaries allow the inclusión of Allium oporinanthum into A. sect.Codonoprasum Reichenb, which includes many complex species, most of them taxonomically not well investigated up to now.
Moreover, for some remarkable morpho-  logical features, such as the spathe valves with a long appendage, the campanulate perigon and the stamens not exserted from perigon, A. oporinanthum is more related to the taxa of A. paniculatum L. group.Within this group, it shows closer resemblance to two other autumn-flowering tetraploid species, distributed in the N Tyrrhenian área, namely A. savii Parí, and A. anzalonei Brullo & al. (BRULLO & al., 1994, 1997).These three species share several morphological characters, such as big size, bulbiliferous bulbs, strong and erect stem, very long spathe valves, erect or suberect and often unilateral white oblong-elliptical anthers, apically papillose ovary, but they differ in the ecological requirements and some flower features.Allium savii occurs on marshes or damp soils and shows bulbs with fibrous outer tunics, 5-6 leaves, up to 25 cm long and 1-2 mm wide, 20-28-flowered inflorescence, larger spathe valve up to 16 cm long, the smaller one up to 11 cm long, perigon 6-7 mm long, white-pinkish to pink-purplish tepals, oblong ovary, obovate capsule.Allium anzalonei is a nemoral species which grows in underwood places and is characterized by 2/3 of the stem length covered by the leaf sheaths, fistulous leaves up 25 cm long and 1-2 mm wide, flower pedicels max.20 mm long, 12 bostryces, by a spathe with 10-11-nerved larger valve, 7-14 cm long, and smaller one 6-9 cm long, by whitish tepals suffused with green, stamen annulus 1 mm high, apically rounded anthers, ovary up to 3.2 mm long, obovate-subglobose capsule 5x4 mm.Significant differences also result from the chromosome complement analysis.In particular, A. savii has three submetacentric pairs and three satellited metacentric pairs, while A. anzalonei shows only one submetacentric pair and one satellited metacentric pair.As to the asymmetry degrees of their chromosome complements (STEBBINS, 1971) both species fall within the type A, like A. oporinanthum.The latter, however, is more closely related to A. anzalonei than to A. savii.In fact, the karyotype of A. anzalonei has a proportion of chromosomes with arm ratio < 2 equivalent to 0.06 (type 2A), while that of A. savii is more symmetric and can be included in the type 1A, having such valué equivalent to 0.0.
These three species are circumscribed in the NW Mediterranean área, but have a distinct geographical distribution (fig.2).
Allium oporinanthum appears to be taxonomically quite isolated from the Iberian taxa belonging in Allium sect.Codonoprasum, showing some resemblance only with A. stearnii Pastor & Valdés, on the basis of its big size, the very long spathe valves and the tetraploid chromosome number 2n = 32 (PASTOR & VALDÉS, 1983;PASTOR, 1985).These two species, however, differ substantially in many morphological features as well as in ecology and flowering time.Allium stearnii has a dense globose inflorescence with patent spathe valves, white or rarely yellow-pinkish perigon 4-4.5 mm long and stamen filaments exserted from perigon.Moreover, it normally grows in synantropic habitats where it flowers in late spring.
In the E Mediterranean área there are other autumn-flowering Allium species, also related to the A. paniculatum group.They are A. euboicum Reich, fil., A. tardans Greuter & Zahar., A. platakisii

Fig. 5 .
Fig. 5. -Leaf cross sections of Allium oporinanthum from Cap de Sant Antoni (A) and Saint Baume (B).See specimens examined for details.