Solenopsis corriasii Brullo, Calvia, Cambria, Siracusa, Giusso & Bacchetta, 2024

Brullo, Salvatore, Calvia, Giacomo, Cambria, Salvatore, Siracusa, Giuseppe, Galdo, Gianpietro Giusso Del & Bacchetta, Gianluigi, 2024, Taxonomical remarks on Solenopsis corsica (Campanulaceae) species complex, with the description of two new species from Sardinia, Phytotaxa 677 (3), pp. 233-250 : 242-245

publication ID	https://doi.org/ 10.11646/phytotaxa.677.3.4
persistent identifier	https://treatment.plazi.org/id/03EA6102-FFB7-FF8D-FF3A-FCC8FC6EFBD6
treatment provided by	Felipe
scientific name	Solenopsis corriasii Brullo, Calvia, Cambria, Siracusa, Giusso & Bacchetta
status	sp. nov.

Treatment

Solenopsis corriasii Brullo, Calvia, Cambria, Siracusa, Giusso & Bacchetta sp. nov. ( Fig. 4 View FIGURE 4 , 7C View FIGURE 7 ).

Type: — Italy, Sardinia. Monte Limbara. Rio Pagghjolu (Tempio Pausania), tra il ponte di Sarra lu Tassu e il ponte di Lu Pagghjolu, affioramenti granitici del torrente, 690–725 m, 40°52’44” N - 9°10’28” E, 3 July 2022, G. Calvia & A. Ruggero s.n. (Holotype CAT).

Diagnosis: —This new species is similar to S. bacchettae in having hairy leaves, bracteole lenght, glabrous calyx lobes, corolla colour, lower lip usually without white macula, anther tube without basal papillae, but it differs in smaller rosettes, shape of leaf blade, floral pedicel up to 105 mm with 2 bracteoles provided by a terminal gland and 0–4 lateral hairs, smaller calyx, much smaller corolla, with tube white-greenish, upper lips of the corolla acute at apex with basal macula uniformely yellow-greenish and papillae covering the throat and the lobe base, anther tube shorter and hairy dorsally, shorter style, smaller seeds.

Description: —Perennial herb, acaulescent, rosulate, 2–5.5 cm in diameter, provided with fibrose slender roots, without stolons. Leaves 8–30 mm long, spathulate, with blade crenate, glabrous or scattered hairy above, 2–12 × 1–7 mm, with petiole 3–18 mm long. Floral pedicels 20–105 mm, with 1–2 bracteoles, entire, 2–5 mm long, 0.25–0.5 mm wide, with glabrous apex and provided with one gland, 0–2 hairs per side above and with 3–5 stipulated glands in the lower part. Calyx 3.5–4.5 mm long, with linear˗lanceolate lobes, 2–2.6 mm long, glabrous. Corolla 6.3–6.5 mm long, bilabiate, with tube white-greenish, 2–3 mm long, 1.4–1.5 mm in diameter; upper lip with 2 lobes ovate˗lanceolate, 2.5–3.3 mm long, 1.1–1.4 mm wide, dark bluish˗lilac, acute at apex, without papillae; lower lip trilobed, 3.5–4.5 mm long, usually totally dark bluish-lilac (sometimes white in the central part), with a small yellow-greenish macula at the base, rarely partially bordered by a reddish halo or with three red small triangles, lobes widely ovate and mucronate at the apex, 2.5–3 × 1.5–2.2 mm, covered by quite dense papillae at the throat and base of lobes, 0.05–0.15 mm long. Stamen filaments free, 2.4–3 mm long, anthers violet, connate into a tube 1–1.2 mm long, wholly encapsulating the stigma; the two lower anthers are smaller, without papillae at basis, each appendiculate at the top with a tuft of hairs, closing a narrow fissure; the three upper anthers are curved, hairy dorsally. Ovary fused with the calyx tube; style whitish, 2.5 mm long; stigma pale lilac, bifid, papillate, with a ring of hairs just under the base. Capsule tuberculate, 3–3.2 mm long. Seeds ellipsoid˗fusiform, brownish shining, 0.40–0.44 × 0.24 mm.

Etymology:—The new species is dedicated to Bruno Corrias (1939–2012), botanist from the University of Sassari and expert on the endemic Sardinian flora.

Phenology:—It flowers and fruits from June to October.

Distribution and ecology: — Solenopsis corriasii grows along the banks of a stream at an altitude of 520–800 m a.s.l., in the crevices of granitic outcrops of stands flooded from winter to early summer ( Fig. 7C View FIGURE 7 ). The populations of this species were observed in partially shaded or sunny growing sites, close to acidophilous holm oak woods dominated by Quercus ilex , Erica arborea , Fraxinus ornus , Arbutus unedo , and sometimes Taxus baccata Linnaeus (1753: 1040) , or riparian woodlands with Alnus glutinosa and Salix atrocinerea . Several shrubs and tufted grasses are frequent in these habitats, e.g. Erica terminalis , Hypericum hircinum subsp. hircinum , Osmunda regalis , Carex panormitana , C. pallescens Linnaeus (1753: 977) , Scirpoides holoschoenus ( Linnaeus 1753: 49) Sojàk (1972: 127) , Brachypodium sylvaticum ( Hudson, 1762: 38) P. Beauvois (1812:101) , etc. Based on the current knowledge, the species is circumscribed to a single site, known as “Riu Lu Pagghjolu” near Tempio Pausania (northern slope of Mt. Limbara), between the locality Li Reni and the artificial lake of Monti di Deu ( Fig. 3 View FIGURE 3 ).

Specimens examined (Paratypes):— Sardinia: Lungo i ruscelli sul Limbara , 16 July 1887, A. Fiori s.n. (FI, RO) ; Monte Limbara, Rio Pagghjolu, tra il ponte di Sarra lu Tassu e il ponte di Pagghjolu, affioramenti granitici del torrente, 690–725 m, 40°52’44” N ˗ 9°10’28” E, 27 August 2022, G. Calvia s.n. (CAT) GoogleMaps ;

Seed micromorphology: —As emphasized by Brullo et al. (2013, 2022. 2023a, 2023b), in the genus Solenopsis the seed testa of the several taxa examined result characterized by quite similar ornamentations. In particular, it is possible to observe very long and narrow cells, anastomosate in the terminal part and separated from each other by more or less deep furrows. Despite a certain similarity in the cell shape, there are also significant differences in morphology and size, providing additional support for the taxonomic identification of the investigated species. The analysis of the morphological features regarding the seed coats of the two new species, reveals significant differences than allied species S. corsica and S. bacchettae . In particular, the seed of S. limbarae ( Fig. 5B View FIGURE 5 ), shows periclinal walls rather flat, 4.4–7.7 μm wide, in the central part crossed along their entire length by a raised and convex band, 1.1–1.3 μm wide, while the anticlinal walls are represented by fairly superficial grooves. As concerns the seeds of S. corriasii ( Fig. 5C View FIGURE 5 ), they have periclinal walls more convex 5.5–8.8 μm wide, in the central part crossed along their entire length by a raised and convex band 1.1–1.5 μm wide, while the anticlinal walls are represented by deeper grooves. In contrast, S. corsica shows more significant differences compared to the two new species ( Fig. 5A View FIGURE 5 ), since it is characterized by periclinal walls convex and smooth, 4.4–7.1 μm wide, rarely crossed along their entire length by an evanescent and thin band, while the anticlinal walls are represented by shallow grooves. Finally, the seeds of S. bacchettae , as illustrated in Brullo et al. (2022, Fig. 6A View FIGURE 6 ), are larger in size than the three previous species. In particular, the periclinal walls are very flat and broad, 5–6 μm wide, and the anticlinal walls are shallow and often inconspicuous, ending near the anastomosis with a marked small elongated pit.

Pollen grains micromorphology: —Based on literature, the pollen grains in Solenopsis were hitherto examined by Dunbar (1975) and Brullo et al. (2022, 2023a), who stressed that they are always 3˗colporate with a perplorate shape. In particular, the pollen of S. corsica is fusiform, measuring 35.7–37.7 μm in length and 18–19.5 μm in width ( Fig. 6 View FIGURE 6 , A 1 View FIGURE 1 , 3 View FIGURE 3 ); the sexine ( Fig. 6 View FIGURE 6 , A 2 View FIGURE 2 ) is slightly reticulate-striate, characterized by rather flattened and not overlapping branched lirae, with a thickness of 0,34–0,75 μm, delineating irregular small lumina (0.17–0.55 μm in diameter). As concerns the pollen of S. limbarae , it is fusiform, with a length of 35.4.7–38.8 μm and a width of 17.1–17.8 μm ( Fig. 6 View FIGURE 6 , C1,3); the sexine ( Fig. 6 View FIGURE 6 , C 2 View FIGURE 2 ) is rather reticulate-striate, characterized by slightly raised and slightly overlapping branched lirae, with a thickness of 0,41–0,68 μm, delimiting irregular small lumina (0.17–0.75 μm in diameter). Conversely, the pollen of S. corriasii is long ellipsoid, measuring 35.7–38.5 μm in length and 15–19.1 μm in width ( Fig. 6 View FIGURE 6 , B 1 View FIGURE 1 ); the sexine ( Fig. 6 View FIGURE 6 , B 2 View FIGURE 2 ) is manifestly reticulate˗striate, characterized by quite raised and markedly overlapping branched lirae, with a thickness of 0,27–0,38 μm, delimiting irregular small lumina (0.10–0.41 μm in diameter). According to Brullo et al. (2022, Fig. 5A View FIGURE 5 ), the pollen of S. bacchettae is fusiform or occasionally long ellipsoid, 39–41 μm in length and 15–16 μm in width; the sexine is slightly reticulate-striate, characterized by rather flattened and not overlapping branched lirae, with a thickness of 0,43–0,71 μm, delimiting irregular small lumina (0.14–1.07 μm in diameter).

Nomenclatural notes:—According to Crespo et al. (1998) and Tison & De Foucault (2014), the proper name of the perennial species of Solenopsis growing in Corsica is S. corsica , which was initially treated by Meikle (1979) as S. minuta (L.) C. Presl subsp. corsica , name used also by Gamisans & Jeanmonod (1987), Gamisans (1999) and Jeanmonod & Gamisans (2007). Previously, the populations of this species were referred by Loiseleur Deslongchamps (1806) and Lamarck & Candolle (1815) to Laurentia minuta ( Linnaeus 1771: 291) A. de Candolle (1839: 410) , while other authors ( Candolle 1839; Coste 1903; Rouy 1908; Litardière 1922; Bouchard 1968) attributed it to Laurentia tenella A. de Candolle (1839: 410) . Actually, Candolle de (1839) describing Laurentia tenella attributed this name to populations occurring in Sardinia, Corsica, Sicily, Crete, Cyprus and also Portugal, mentioning in the protologue several binomials published previously by various authors, which therefore are to be considered as syntypes of this name, quoting also two polynomials, one published by Tournerfort (1700) sub “ Rapuntium Creticum minimum Bellidis folio flore maculato ” and another by Boccone (1697) sub “ Rapunculus aquaticus minimus , etc.”. Furthermore, Candolle de (1839), in the protologue of Laurentia tenella , did not make any reference to Lobelia tenella Linnaeus (1767: 120) , while he considered Laurentia minuta (= Lobelia minuta L.) as a distinct species growing at the Cape of Good Hope ( South Africa), highlighting that in the Linnaean Herbarium he did not find any specimen identified with this name. Besides, he mentioned as synonym of Laurentia minuta also Solenopsis minuta , name proposed by C. Presl (1836) as a new combination based on Lobelia minuta L., without specifying its distribution. Later, Meikle (1979) neotypified Solenopsis minuta with the specimen (n. 861, P!) collected in Crete by Tournefort (1700), based on an interpretation of Lamarck (1792), who considered Lobelia minuta L. as a plant growing in Crete and Minorca, cultivated in the Botanical Garden of Paris, without any justification regarding the origin of the Linnaean material. This treatment was accepted by Crespo et al. (1998), who considered S. minuta as a species distributed in Crete, Sicily, and Sardinia. Even though we do not agree with this treatment, especially due to the ambiguity of the name Lobelia minuta , it is evident that the Corsica populations should be attributed to Solenopsis corsica . Regarding the perennial populations of Solenopsis occurring in Sardinia on granitic substrata of Mt. Limbara, they were reported for the first time by Nicotra (1896), who attributed them to Laurentia tenella , while Moris (1840 –1843) mentioned with the same name only the populations occurring on the carbonate substrata of the central-eastern part of the island, which are currently referred to S. bacchettae . Recently, the Limbara populations were referred by some authors ( Conti et al. 2005; Arrigoni 2013; Pezzetta & Ceschetti 2018) to Solenopsis minuta subsp. corsica , while others ( Crespo et al. 1998; Brullo & Guarino 2018; Calvia & Ruggero 2020, 2023) referred it to Solenopsis corsica . Based on field surveys and morphological investigations on living plants, as well as on micro-morphological analyses of seeds and pollen grains, the northern Sardinian populations are quite well diversified from the Corsica ones. The differences concerning both vegetative and reproductive structures allowed to recognize 3 taxa separable at specific level ( Tab.1). They are: Solenopsis corsica exclusively occurring in Corsica, S. limbarae growing on Mt. Limbara and nearby Mountains of Alà, and S. corriasii circumscribed to a small and isolated stand in the northern part of Mt. Limbara. In particular, S. limbarae , due to its very small flowers with a bicoloured corolla, shows closer relationships mainly with S. corsica and for this reason it was previously attributed to the last species (cf. Crespo et al. 1998). Conversely, S. corriasii in having bigger flowers and often uniformly colored corolla appears more similar to S. bacchettae , species occurring in central-eastern Sardinia ( Brullo et al. 2022). As previously emphasized, significant differences were observed in the size and shape, as well as in the microsculptures, of the seeds and pollen grains of these species.