Typus: Sardinia. Sulcis: Cala Piombo (Teulada - CI), 3 m, 38°53′44.69″N 8°38′ 37.29″E, SW 215°, incl. 45°, panchina tirreniana, termomedit inf./secco inf., 10.V.2007, G. Bacchetta, S. Cinus, D. Cogoni, G. Fenu & S. Pinna 44/07 (holo-: CAT; iso-: CAG, CAT, FI).

Astragalo terraccianoi affinis, foliolis ovato-lanceolatis, stipulis erectis apice, 4.5-5 mm longis, 1-nervatis, dense pilosis exteriori superficie, marginis pilis 0.1–0.3 mm longis, bracteolis 1–1.4 mm longis, base calyce insertis, calyce cylindrico-tubuloso, 6.5–8 mm longo, prufunde inciso dorso, calycis dentibus triangularibus, inferioribus 0.7–0.8 mm longis, vexillo 11.5–15.5 × 5.5–6 mm, alis 14–15 mm longis, carina 11–11.5 mm longa, anther subcirculari, 0.7 mm longa, pistillo 12–12.5 mm longo, ovario sparsim piloso, legumine 10–12 × 3–4 mm, oblongo-ovoideo, rostro recto, 2–2.5 mm longo, semine 2.4–2.5 × 1.5–1.6 mm, testa rugosa differt.

Dwarf shrub forming a dense compact, spiny cushion, 20–40(-60) cm tall. Stems woody, very branched, tough, with persistent stipules and rachis in the old part of the branches. Leaves imparipinnate 2.5–4 cm long, with rachis creamwhitish juvenile covered by scattered hairs that are protracted into a straight spine, shorter than the upper leaflets. Leaflets ovate-lanceolate, green, obtuse to acute at apex, 7–8 paired, 2.5–6 × 1–2.2 mm, covered by appressed medifixed hyaline hairs. Stipules ovate, 4.5–5 mm long, joined to the rachis from about half-way, acute to apiculate and erect at the apex, coriaceous, straw-coloured, uninerved, densely hairy on the outer faces and at the margin with hairs 0.1–0.3 mm long. Raceme 2–4 flowered, with peduncle 5–15 mm long. Bract lanceolate to ovate-lanceolate, hyaline, apiculate, 1.4–1.7 mm long, densely hairy. Bracteoles ovate-lanceolate, densely hairy, 1– 1.4 mm long, inserted at the calyx base. Calyx cylindric-tubulose, two lipped, deeply incise on the back until the middle part, 6.5–8 mm long, 2.5–3 mm in diameter, densely covered by medifixed hyaline and black hairs, teeth triangular, the lower ones 0.7–0.8 mm long, the upper ones 0.6 mm long. Corolla white, tinged with pink-lilac in the keel, 14.5– 16.5 mm long; standard platonychioid, spatulate, flat at the margin, retuse at apex, 11.5–15.5 × 5.5–6 mm. Wings 12– 14 mm long; keel 11–11.5 mm long. Stamen tube (fused region of the filaments) 11–13 mm long. Anther yellow, subcircular, 0.7 mm long. Pistil 12–12.5 mm long. Ovary sparsely hairy. Style glabrous and curved. Stigma slightly papillose, hemispheric. Legume 10–12 × 3–4 mm, hairy, with hairs white and black, 0.3–0.7 mm long, irregularly oblong-ovoid with a long beak straight, 2–2.5 mm long; keel 0.9–1.1 mm wide. Seeds reniform, 2.4–2.5 × 1.5–1.6 mm, brown, laterally compressed, with testa densely rugose.

Etymology. — The specific epithet refers to “Tegula'“, the ancient name of the town and cape of Teulada.

Seed micromorphology. — In A. tegulensis the ornamentation of the testa is well-differentiated from that in A. terraccianoi (Fig. 3). In particular, the seed near the hilum is quite smooth, while the rest of the testa surface is uniformly rugose and cerebriform in shape. In A. terraccianoi the testa is uniformly reticulate.

Distribution, ecology and conservation status. — Astragalus tegulensis is an halophyte occurring in SW Sardinia at an altitude of 1-5 m and localized in the Cala Piombo bay of Capo Teulada (Fig. 4). This species is represented by a small population found in the westen part of the bay on Paleozoic metamorphytes and Tyrrhenian bioclastic calcareous sandstones (panchine). It grows on lithosoils or on developed poorly soils, from a pedogenetic point of view. Astragalus tegulensis is distributed in the Mediterranean xeric-oceanic bioclimate, in the lower thermomediterranean belt and is a lower dry ombrotype. Phytosociologically it is a member of a coastal chasmophytic and chasmo-comophytic communities of cliffs and lithosols that are splashed by marine salt spray, belonging to the Crithmo-Limonietea Br.-Bl. 1952. In this vegetation type halophytes such as Anthemis maritima L., Crithmum maritimum L., Dactylis glomerata subsp. hackelii (Asch. & Graebn.) Cif. & Giacom., Daucus gingidium L., Limonium tigulianum Arrigoni & Diana, Lobularia maritima (L.) Desv. subsp. maritima, Lotus cytisoides subsp. conradiae Gamisans, Scabiosa atropurpurea subsp. maritima (L.) Arcang. and Spergularia media (L.) C. Presl are frequent.

At present the only known population of this new species is unfortunately threatened by the military activity (rifle drilling, tank movements and mock battles). Thus, A. tegulensis may be considered, based on the regional red lists of the IUCN, as an endangered species (EN). In particular, based on the IUCN criteria (2001, 2006), the following specific category is proposed: EN B1ab(ii,iii, v) + 2ab(ii,iii,v).

Taxonomical notes. — Astragalus tegulensis belongs clearly to sect. Melanocercis Bunge of subgen. Cercidothrix Bunge (Chater, 1968; Chamberlain & Matthews, 1969) based on its spiny suffruticous habit, mediafixed black and hyaline hairs, imparipinnate leaves with a spine-like rachis, stipules adnate to the petiole, flowers joined in racemes, tubular calyx, and legume exceeding calyx. In this section, described by BUNGE (1868, 1869), A. tragacantha L. and its allied species (A. balearicus Charter, A. terraccianoi and A. thermensis Vals.) should be included.

In particular, A. tegulensis shows a close relationship to A. terraccianoi based on the habit, leaves, corolla size and stamen tube, but it differs in numerous other features that are listed in Table 1. The differences concern mainly the colour, shape and size of leaflets; the size and insertion of the bracteoles; upper lip sinus of the calyx; shape and size of the standard, wings and keel; shape, size and beak of the legume; shape, size and testa of the seed (Fig. 5).

From taxonomical and ecological point of view, A. tegulensis and A. terraccianoi are closely related to A. tragacantha, species distributed along the coast of Provence (France), Catalonia (Spain) and Algarve (Portugal), as emphasized by Valsecchi (1994) and Podlech (2008). In fact, A. tragacantha can be considered as a species complex represented by taxa with scattered and but circumscribed distribution in the western Mediterranean area, where they grow in rocky or sandy places. At present, they are represented by relict populations dating back to the Tertiary, linked to habitats characterized by a humid sea wind (Fig. 6). In these particular ecological conditions species having pulvinate and thorny habit are favourized (Pignatti & al., 1980). The communities growing in these places are very specialized, showing a tolerance to sea spray. Phytosociologically, they are usually included in the Chritmo- Limonietea or sometimes in the class of AmmophyleteaWesth., Dijk & Passchier 1946.

According to Bacchetta & Brullo (2006), in Sardinia there are other species belonging to sect. Melanocercis, such as A. genargenteus Moris and A. gennarii Bacch. & Brullo, but they fall into the A. sirinicus Ten. group. Both species are orophytes, found on the top of Gennargentu massif (granitic substrates) and Mt. Albo (limestone), respectively. Note worthy morphological differences distinguish these species from A. tegulensis, even if it shares some similarities with A. gennarii. In particular, the latter species differs in it larger size (up to 80 cm tall), leaflets 6-11 pairs, oblong, stipules widely triangular, 5-6 mm long, longer bracts (1.5-3 mm), calyx not incised in the back, longer calyx teeth (1–1.5 mm), bigger standard (14–18 × 7–8 mm), longer keel (12–15 mm), bigger seeds (2.6–2.9 mm × 1.6–1.7 mm) with a reticulate testa.

Basing on morphological, chorological and ecological data, A. tegulensis can be considered a vicariant of A. terraccianoi arose from the old geographical isolation of the Sulcis-Iglesiente plate (Cherchi & Montadert, 1982). It is important to emphasize that the SW Sardinia is very rich in rare and endemic taxa, exclusive to this biogeographic sector, many of which are paleoendemics (Bacchetta & Pontecorvo, 2005; Bacchetta, 2006; Bacchetta & al., 2007).

Additional material examined. — SARDINIA: Spiaggia di Cala di Piombo, Capo Spartivento, 24.IV.1897, U. Martelli s.n. (M); Punta della Torre, C. Teulada, 08.XI.1981, M. Ballero & E. Bocchieri s.n. (CAG); Punto Cogodulos, C. Teulada, 08.XI.1981, M. Ballero & E. Bocchieri s.n. (CAG); Cala Piombo (Teulada — CI), 2.5 m, 38°53′42.20″N 8°38′43.77″E, SW 215°, incl. 10, panchina tirreniana, termomedit sup./secco sup., Crithmo-Limonietea, 16.VI.2006, G. Bacchetta, G. Fenu, P. Cuccus & G. Mandis 138/06 (CAG).