Solenopsis mothiana C. Brullo, Brullo & Giusso, 2013

Brullo, Cristian, Brullo, Salvatore & Galdo, Gianpietro Giusso Del, 2013, Solenopsis mothiana (Campanulaceae), a new species from Sicily, Phytotaxa 145 (1), pp. 15-26 : 16-20

Solenopsis mothiana C. Brullo, Brullo & Giusso , sp. nov. ( Figs. 1 , 2B–D )

Species annua satis distincta ab aliis speciebus notis generis Solenopsis , a quibus caulibus pluribus, brevissimis, prostrato-ascendentibus, basi ramosis, corolla candida, minuta , 3–3,5 mm longa, lobis sub-conniventibus ad maturitatem praecipue differt

Type:— ITALY. Sicily: Isola Grande dello Stagnone di Marsala ( Prov. di Trapani ), depressioni umide debolmente salse, sommerse nel periodo invernale, 37° 52’ 45’’ N, 12° 26’ 53’’ E, 19. April. 2010, S. Brullo s.n. (holotype CAT!) .

Annual herb, (2) 3–8 cm high, sub-caulescent, glabrous, green. Stems several, contracted, prostrate-ascending, branched at the base. Leaves oblanceolate, 4–20 x 2–6 mm, petiolate, sub-entire to irregularly undulate at the margin, arranged in a basal rosette and also cauline. Petiole 3–6 mm long. Flowers solitary on axillary pedicel, 1–6 cm long, near the middle with a bracteole 2–8 mm long. Calyx 3.8–4 mm long, with lobes lineartriangular, acute, 2.3–2.5 long, uninerved. Corolla white, tubular, 3–3.5 mm long, bilabiate, with lobes subconnivent, subequalling the tube; upper lip with 2 lobes ovate-lanceolate, 1.5–1.7 mm long, acute, leviter tinged with violet in the central part of the nervation; lover lip with 3 lobes oblong, 1–1.2 mm long, obtuse, on the inside provided with numerous papillae clavate, 0.1–0.3 mm long. Staminal filament white, 1.5–1.7 mm long, below fused with the corolla. Anthers violet, upper bearded, connate into a tube 0.7–0.8 mm long, wholly encapsulating the stigma. Ovary included in the calyx tube; style whitish, tinged with brown-violet at the base and apex, 2–2.5 mm long; stigma white, capitate, papillate. Capsule bilocular, loculicide, 2.5–3 mm long, Seeds flat, ellipsoid, brown, shining, 0.4 x 0.2 mm.

Seed micro-morphology:— According to literature ( Murata 1992, 1995, Haridasan & Mukherejee 1993, Serra & Crespo 1997, Crespo et al. 1998), the micro-sculpturing features of the seed coat surface in Campanulaceae subfamily Lobelioideae Burnett (1835: 942) show some diagnostic value. The surface structure of mature seeds is characteristic and constant for a given species or group of allied species. The genus Solenopsis has been investigated by Serra & Crespo (1997) and Crespo et al. (1998), who emphasized that the seed coat sculpturing is quite similar for the species of this genus, since they are all characterized by a testa longitudinally furrowed with very long and smooth cells. Our SEM investigations carried out on S. mothiana , as well as on the most closely allied S. laurentia , confirm what has already been highlighted by the above-mentioned authors, even if some relevant differences can be detected in the testa of the two species. In particular, S. mothiana is characterized by anticlinal walls slightly depressed and periclinal walls rather flat or slightly convex ( Fig. 3B, D ), while S. laurentia has anticlinal walls markedly sulcate-depressed and periclinal walls very convex often slightly keeled ( Fig. 3A, C ).

Phenology:— Flowering March to May, fruiting April to May.

Etymology:— The specific epithet refers to Mozia (Latin: Mothia), a prosperous Phoenician colony founded in the late VII century BC on the islet of San Pantaleo, which is located in the heart of a large lagoon known as “Stagnone di Marsala”.

Habitat:— Solenopsis mothiana is an ephemeral hygrophyte growing on flat surfaces periodically submerged in winter by slightly salty shallow water ( Fig. 2A ). Such depressions may occupy rather wide areas and, being localized very close to the sea, they are covered with a thin layer of sodium chloride when completely dried up. Usually, this species is rather spread in its growing sites where it occurs together with other hygrophilous therophytes such as the Isoeto-Nanojuncetea class ( Brullo & Minissale 1998), including Polypogon subspathaceus Requien (1825:386) , Lythrum hyssopifolia Linnaeus (1753: 447), Juncus bufonius Linnaeus (1753: 328) , Anagallis parviflora Hoffmannsegg & Link. (1813: 325) , among others. Less frequently, it is found on shady, humid and sub-nitrophilous habitats, such as under the canopy of the dwarf shrubs, where it has been previously recorded by Brullo et al. (1994) as Solenopsis minuta subsp. annua , an annual species characterizing a sciaphilous micro-coenosis of the Geranio-Cardaminetalia hirsutae class. Solenopsis laurentia , a closely allied species, frequently occurs on the same island. However, this species is ecologically distinct from S. mothiana . As observed by Brullo et al. (1994), S. laurentia is typically localized on small ponds within the dry grassland dominated by Lygeum spartum Linnaeus (1954: 522) .

Distribution:— Solenopsis mothiana appears to be a very rare species found exclusively in the Stagnone islands, near Marsala (NW Sicily). This archipelago consists of four islets, from the largest to the smallest, Isola Grande, Mozia (also known as San Pantaleo), Santa Maria and La Schola ( Fig. 4 ). S. mothiana was found only at “ Isola Grande”, and its occurrence on the other islets is rather unlikely, due to a lack of suitable ecological conditions. According to Brullo et al. (1995), this species represents a punctiform Sicilian endemic, belonging to the Drepano-Panormitano biogeographic sector.

Conservation status:— The area where Solenopsis mothiana was found falls within a Natural Reserve of north-western Sicily, established in 1984 and named “Riserva Naturale Regionale delle Isole dello Stagnone di Marsala”, ( Fig. 4 ). The islet Isola Grande extends for 1.2 km ², and it is geologically characterised by low calcarenitic outcrops, interspersed with more or less large sandy-silty marshes periodically flooded by rainwater and seawater, some of which have been turned into salines for salt production. All the islets of the archipelago are just few tens to a maximum of 200 meters from the Sicilian coastline, and they form a lagoon system whose deepest point is 2 meters. Although the few growing sites of S. mothiana are not particularly threatened, it must be stressed that the new species is a microphyte forming ephemeral populations of about 200–300 individuals, whose habitats could be potentially destroyed by drainage works or even by small roads located close to the salines. In addition, according to European Commission (1992, 2007), these really peculiar environments are classified as priority habitats, being included in the "standing water group". In particular, the growing sites of S. mothiana are classified as Mediterranean temporary ponds (“habitat 3170”) ( Bagella et al. 2007, Ruiz 2008). Considering its rarity and low number of individuals linked to threatened habitats of great relevance for biodiversity conservation, Solenopsis mothiana should be classified as an endangered species. In particular, based on the IUCN criteria ( IUCN 2010), we propose to include this species in the following category: EN D (endangered with very small populations or very restricted distributions).

Figures

FIGURE 1. Diagnostic features of Solenopsis mothiana. A. Habit. B. Flower (lateral view). C. Flower (dorsal view). D. Flower (ventral view). E. Open calyx. F. Open corolla. G.Corolla papillae. H. Style and stigma. I. Anthers. J. Capsule. K. Seeds. L. Leaves. Illustration by Salvatore Brullo based on S. Brullo s.n. (CAT).

FIGURE 2. Phenological features of Solenopsis mothiana. A. Sub-salty depressions colonized by S. mothiana (Isola Grande). B. Habit of S. mothiana (cultivated material). C. B. Habit of S. mothiana (natural stands). D. Flower detail of S. mothiana. Photos by G. Giusso del Galdo (B, D) and S. Sciandrello (A, C).

FIGURE 3. SEM micrographs of seed coat of Solenopsis laurentia (A, C) and S. mothiana (B, D) at low magnification (A, B x 250) and at high magnification (C, D x 1000) from material of Isola Grande, S. Brullo s.n. (CAT).

FIGURE 4. Geographical distribution of Solenopsis mothiana (full dots). “Riserva Naturale delle Isole dello Stagnone di Marsala limits (red line).