Genista desoleana Valsecchi (1986: 243)

Bacchetta, Gianluigi, Brullo, Salvatore, Chiapella, Laura Feoli, Velari, Tiziana Cusma, Fenu, Giuseppe & Galdo, Gianpietro Giusso Del, 2020, Taxonomic remarks on Genista salzmannii group (Fabaceae) in Sardinia and Corsica, Phytotaxa 449 (1), pp. 31-51 : 37-40

Genista desoleana Valsecchi (1986: 243)

A. subsp. desoleana , Fig. 5

Type:— ITALY. Sardinia: Cuglieri: pianoro roccioso a Badde Urbara , 25 July 1974, F. Valsecchi s.n. (holotype SS!; isotypes: FI, SS) .

Dwarf shrub, pulvinate-erect, robust, 30–60 cm tall, with branches not very rigid, with spiny apex, weakly striate, sericeous. Leaves 1-foliate, sessile, stipulate, linear-oblong, hairy, 5–7 mm, caducous. Inflorescences lax, 1–5-flowered. Bracts linear-oblanceolate, flat, 4–7 mm, longer than the pedicel. Bracteoles linear-lanceolate, acute, 2–3 mm, longer than the pedicel, inserted at the low half part of the pedicel. Pedicel 2–3 mm. Calyx hairy, conic-campanulate, 5.5–7 mm long, with hairs 0.3–0.8 mm long, with veins incrassate and decurrent only in the lips; lower lip 3.5–4 mm with triangular teeth 1-nerved, the central one 1.4–1.6 mm long, the lateral ones 0.9–1.4 mm long; upper lip shorter than the lower one, 2.8–3.5 × 1.6–1.8 mm. Floral buds with wings covered by the standard. Corolla yellow; standard retuse at apex, 9.5–10.5 × 9–9.2 mm, sericeous on the back; wings 9–9.5 mm, with a tuft of hairs on basal gibbosity; keel 9–9.5 mm, sericeous on outer faces. Staminal tube 10 mm long, anthers yellow, apiculate at apex, upper ones elliptical, 1.6–1.8 mm, lower ones ovate-lanceolate, 1–1.1 mm. Pistil 9 mm, stigma papillose, oblique. Pod sericeous, oblong, apiculate, flattened, pale brown, 18–22 mm long, (2)4–7 seeded. Seeds ovate, flattened, brown-olivaceous, maculate, 2.5–3.0 × 2–2.3 mm.

Phenology:— Flowering late April to June, fruiting July to August ( Valsecchi 1993).

Karyology:— The somatic chromosome number of Genista desoleana subsp. desoleana was found 2 n = 2x = 18+0-4 B on material (coming) from Cuglieri, Badde Urbara ( Villa 1988) and Santu Lussurgiu, Punta Badde Urbara ( Villa 1988,) Cusma Velari et al. 2011).

Seed micro-morphology:— Cell boundaries are indistinguishable. Seed coat is homogeneous and appears densely and irregularly rugose-reticulate, bordering minute foveae, rugose at the bottom, with raised and crested wrinkles ( Fig. 4 C–D ).

Distribution and Habitat:— In Sardinia, this plant occurs only in the Goceano-Logudorese biogeographic sector ( Fenu et al. 2014), and in particular in the Montiferru massif (CW Sardinia) on Plio-Pleistocenic volcanic substrates where it grows on summit plateaux with mature soils at an elevation never exceeding 1000 m a.s.l. ( Fig. 1 ). From the bioclimatic point of view, it falls within the upper meso-Mediterranean belt with humid ombrotype ( Bacchetta et al. 2009), where it grows within the dwarf shrubby plant communities floristically characterized by Armeria sardoa Sprengel (1827: 127) subsp. sardoa , Dianthus ichnusae Bacchetta, Brullo, Casti & Giusso (2010: 146) subsp. ichnusae , Helichrysum microphyllum ( Willdenow 1803: 1863) Cambessedes (1827: 272) subsp. tyrrhenicum Bacchetta, Brullo & Giusso (in Angiolini et al. 2005: 272), and Thymus herba-barona Loiseleur (1807: 360) .

Additional specimens examined:— ITALY. Sardinia: Badde Urbara (Montiferru), 3 June 2002, G. Bacchetta, S. Brullo, M. Casti & G. Giusso del Galdo s.n. ( CAT!) ; Punta Badde Urbara, Santu Lussurgiu (Oristano), 3 June 2002, G. Bacchetta s.n. ( TSB 91817-8 !) ; Montiferru, Badde Urbara , 30 May 2004, G. Bacchetta, S. Brullo & M. Casti s.n. ( CAT!) .

B. subsp. martellii Bacchetta, Brullo & Giusso , subsp. nov., Fig. 6

Type:— ITALY. Sardinia: Badde Salighes, Bolotana, 3 June 2002, S. Brullo , M. Casti & G. Giusso del Galdo s.n. (holotype CAT!; isotypes CAG!, CAT!) .

A typo habitu erecto, altiorem, bracteolis brevioribus, pedicello subequalibus vel brevioribus, calyce breviore, labio inferiore breviore, dente centrali longiore, dentibus lateralibus brevioribus, labio superiore breviore, vexillo angustiore, antheris rotundatis apice, brevioribus, legumine breviore, seminibus diametro minore differt.

It differs from the typical subspecies in having habit erect, up to 90 cm tall, bracteoles 1.5–2 mm, subequal or shorter than the pedicel, calyx 5–5.5 mm long, with lower lip 2.5–3 mm long, central tooth 1.6–2 mm long, the lateral ones 1.4–1.6 mm long, upper lip 2–2.5 mm long, standard rounded to slightly retuse at apex, 7.2–8.2 mm wide, anthers rounded at apex, upper ones 1–1.2 mm long, lower ones 0.7–0.8 mm, pods 10–17 mm long, 3–5-seeded, and seeds 1.5–2 mm in diameter.

Phenology:— Flowering late May to July, fruiting August to September.

Karyology:— The somatic chromosome number of Genista desoleana subsp. martellii was found 2 n = 2x = 18+2 B on material from Bolotana, Badde Salighes and Bono, M. Rasu ( Cusma Velari et al. 2011), sub G. desoleana .

Seed micro-morphology:— Cell boundaries are indistinguishable. Seed coat is homogeneous and it appears loosely and irregularly rugose-reticulate, bordering wide foveae, densely rugose at the bottom, with smoothed and corrugated wrinkles ( Fig. 4 A–B ).

Distribution and Habitat:— This subspecies is distributed only in the Goceano-Logudorese biogeographic sector ( Fenu et al. 2014), along the Marghine-Goceano range (CN Sardinia) on Paleozoic metamorphic rocks ( Fig. 1 ). It grows on cacuminal stands with undeveloped soils at an elevation of 900–1250 m a.s.l. From the bioclimatic point of view, this area falls within the lower supra-submediterranean humid belt ( Bacchetta et al. 2009) and is characterized by the dominance of dwarf shrubby plant communities with Armeria sardoa subsp. sardoa , Bunium corydalinum Candolle de (1830: 117), Dianthus ichnusae subsp. toddei Bacchetta, Brullo, Casti & Giusso (2010: 147) , Galium corsicum Sprengel (1827: 39) and Thymus herba-barona .

Notes:— Genista desoleana , morphologically quite related to G. lobelii Candolle de (1805: 499) from SE France, is distributed in the northern part of the Tyrrhenian sea (Sardinia, Elba and Liguria) as already highlighted by Valsecchi (1986, 1993). As concerns the Sardinian populations, it is possible to distinguish two subspecies that can be considered as geographical vicariants linked to different ecological conditions. Actually, subsp. martellii grows on metamorphic substrata at higher elevations, in an area characterized by mesic conditions, while subsp. desoleana in Sardinia occurs at lower elevation on volcanic substrates, in an area characterized by mesomediterranean climatic conditions ( Bacchetta et al. 2009). As concern the populations from Elba and Liguria, we deem that more in-depth surveys would be necessary in order to verify their taxonomical position.

Additional specimens examined (paratypes):— ITALY. Sardinia: Monte Rasu ( C.na del Goceano), 30 May 2002, G. Bacchetta, S. Brullo , M. Casti & G. Giusso del Galdo s.n. ( CAT!) ; Monte Rasu, Bono ( SS), 19 May 2004, M. Casti & G. Senis s.n. ( CAG!) ; Monte Rasu, Bono , 20 June 2004, M. Casti s.n. ( CAT!, CAG!) ; Badde Salighes , 20 June 2004, M. Casti s.n. ( CAT!, CAG!) ; Badde Salighes, Bolotana ( NU), 20 June 2004, M. Casti & G. Senis s.n. ( CAG!) .

Figures

FIGURE 1. Distribution map of Genista sect. Erinacoides in Sardinia and Corsica.

FIGURE 4. SEM micrographs of seed testa of Genista desoleana subsp. martelli (A–B), G. desoleana subsp. desoleana (C–D), G. nuragica (E–F), and G. pichisermolliana (G–H).

FIGURE 5. Diagnostic features of Genista desoleana subsp. desoleana. A. Flowers. B. Open calyces with bracteoles and bract. C. Standard (ventral view). D. Standard (dorsal view). E. Wings. F. Keel (ventral view). G. Keel (dorsal view). H. Staminal tube (open). I. Anthers. J. Pistil. K. Stigma. L. Pods. M. Seeds. N. Bracteoles. O. Bracts. Illustration by S. Brullo based on living material coming from the type locality (CAT).

FIGURE 6. Diagnostic features of Genista desoleana subsp. martellii. A. Flowers. B. Standard (ventral view). C. Standard (dorsal view). D. Wings. E. Keel (ventral view). F. Keel (dorsal view). G. Open calyces with bracteoles. H. Staminal tube (open). I. Anthers. J. Pistil. K. Stigma. L. Pods. M. Seed. N. Bracts. O–P. Bracteoles. Illustration by S. Brullo based on living material coming from the type locality (CAT).