Ephedra strongylensis Brullo, C. Brullo, Cambria, Ilardi, Siracusa, Minissale & Giusso, 2022

Brullo, Salvatore, Brullo, Cristian, Cambria, Salvatore, Ilardi, Vincenzo, Siracusa, Giuseppe, Minissale, Pietro & Galdo, Gianpietro Giusso Del, 2022, Ephedra strongylensis (Ephedraceae), a new species from Aeolian islands (Sicily), Phytotaxa 576 (3), pp. 250-264 : 251-261

Ephedra strongylensis Brullo, C. Brullo, Cambria, Ilardi, Siracusa, Minissale & Giusso sp. nov. ( Figs. 1–6 )

Type: ITALY. Sicily: Isole Eolie, Stromboli, Ginostra presso S. Lazzaro , 38°46’48” N, 15°11’46”E, 4 July 2022, S. Cambria s.n. (holotype, CAT; isotypes, CAT) .

Diagnosis: — This species is similar to Ephedra aurea , but it differs in its twigs with smaller diameter, leaves with a green triangular rib, male cones with a very longer pedicel and bracts shorter, synangiophore shorter with few synangia, female cones with very longer pedicel and bracts shorter and rounded at the margin, the lower and medium bracts longer connate, the upper one more briefly connate, ovule longer exserted from the upper bract, female strobilus at maturity smaller, with bracts pale red, seeds smaller, ellipsoid, longer exserted from the upper bracts

Description: —Dioecious subshrub, erect, 40–100 cm tall, old stems woody, erect or procumbent, bark brownish-gray. Twigs erect, fasciculate and densely inserted at the nodes, green, cylindrical, finely furrowed and scabrous along the ribs, 0.8–1.2 mm in diameter; internodes 1–3.5(–5)cm long, not easily disarticulating. Leaves opposite, 1–1.25 mm long, membranous, fused for most of their length, briefly free and not recurved at the apex, each with an acute green triangular rib on the back and a coriaceous basal ring, turning brown at maturity. Male cones ellipsoid, 4–7 mm long, 4–7 mm in diameter, long pedicellate, with pedicel 2.5–6 (–10) mm long, usually opposite; bracts binate in 3–6 pairs, ovate, acute, connate per 1/2–3/4, 0.5–1 mm long, 1–2 mm wide, ovate; perianth exserted from the subtending bract, obovate, 2 mm long, deeply bilobed; synangiophore 2–2.5 mm long, long exserted from perianth, with 3–5 synangia, sessile, densely aggregated at top. Female cones uniovulate, ellipsoid, isolated to 4-clustered, 5.5–6.5 mm long, 2.5– 3.5 in diameter, long pedicellate, with pedicel 2.5–10 mm long; bracts green connate in 3 pairs, broadly ovate, rounded at apex, hyaline at the edges, connation ranging 4/ 5 in lower bracts, 1/2–2/ 3 in middle bracts and 2/ 3 in upper bracts; lower bracts 0.5–1 mm long, middle bracts 1.5–2 mm long and upper bracts 4.5–5 mm long, shortly mucronate at the apex; ovule 4–4.5 mm long, ellipsoid, 1.5–2.5 mm exserted from upper bracts; micropilar tube straight, ca 1.5 mm long, exserted 0,7– 1 mm from the ovule. Female strobilus at maturity ovoid to globose-ovoid, 6–7 × 3.5–4 mm, with bracts always pale red. Seeds 5–5.5 × 2.5–2.6 mm, blackish-brown, slightly striated longitudinally, fusiform, exserted 1–2 mm from upper bracts.

Etymology: — The specific epithet refers to “ Strongyle ”, Latin name of Stromboli, island of the Aeolian Archipelago (Sicily).

Phenology: —It is a dioecious plant flowering in April–May and producing seeds from July to August.

Seed micro-morphology:—On the basis of SEM analyzes, the seeds of Ephedra strongylensis have a fusiform shape, with dimensions of 5–5.5 × 2.5–2.6 mm ( Fig. 7A ). The seed testa is differentiated by short longitudinal rectangular cells, 16–28 × 4–6 μm, separated by a slight groove ( Fig. 7B–C ). The anticlinal walls are thin and flat, with a slight central incision, while the periclinal ones are smooth and slightly convex. In relation to Ickert-Bond & Rydin (2011) observations, this type of ornamentation does not seem frequent in Ephedra . Seed coat similar, but with cells clearly longer and characterized by periclinal walls flat and rugose, with anticlinal walls quite raised were detected in E. aurea by Brullo et al. (2022, Fig. 5A ). As concerns the seed coat of E. fragilis , as emphasized by Ickert-Bond & Rydin (2011), it is very different, since the cells are 50–150 μm long with periclinal walls convex.

Pollen morphology:—Micromorphological investigations carried out on pollen grains of Ephedra strongylensis emphasized that it belong to type “A” (cf. Bolinder et al., 2016), showing an elliptical shape rounded at the poles, with 12–16 plicae, very compact and rounded on the back, ca. 4–5 μm high, with unbranched and linear line in the groves (pseudosulci), the absolute size (equatorial lenght and diameter) is 46–50 × 20–27 μm ( Fig. 8 ). Therefore, the E. strongylensis pollen shows close relationships with that one of other Mediterranean species, such as E. fragilis Desf. , E. foeminea Forssk. and E. aurea Brullo et al. , though in the latters it is morphologically well differentiated, since usually characterized by 8–12 plicae (see Norbäck Ivarsson 2014, Bolinger et al. 2015, 2016 and Brullo et al. 2022). As regards a possible affinity between E. strongylensis and E. distachya , it must be excluded, since the latter has longer pollen belonging to type “B”, with 4–8 plicae and branched pseudosulci ( Norbäck Ivarsson 2014).

Distribution and ecology: — Currently, Ephedra strongylensis was exclusively surveyed on the island of Stromboli and the nearby islet of Strombolicchio in the Aeolian archipelago (Sicily), where it grows in two limited stands ( Fig. 9 ). Here it is localized on basaltic rocks, originated from ancient lava eruptions, where it is a member of xerophilous maquis characterized by Euphorbia dendroides Linnaeus (1753: 462) , Pistacia lentiscus Linnaeus (1753: 1026) , Olea europaea Linnaeus (1753: 8) , Artemisia arborescens ( Vaillant, 1754: 338) Linnaeus (1763: 1188) , Genista tyrrhena Valsecchi (1986: 145) subsp. tyrrhena , etc. ( Fig. 5 ). It should be noted that the flora of the Aeolian islands (including Stromboli and Strombolicchio) hosts several endemic or rare species, often showing a remarkable taxonomic isolation, whose occurrence has no clear correlation with the relatively recent origin of this volcanic archipelago. Among the most significant taxa, the following can be mentioned: Genista tyrrhena subsp. tyrrhena , Cytisus aeolicus Gussone (1834: 221) , Bituminaria basaltica Minissale, C. Brullo, Brullo, Giusso & Sciandrello (2013: 2) , Centaurea aeolica Gussone ex Lojacono (1903: 136) , Silene hicesiae Brullo & Signorello (1984: 141) , Erysimum brulloi G. Ferro (2009: 298) , Anthemis aeolica Lojacono (1903: 84) , Eokochia saxicola ( Gussone 1855: 275) Freitag & G. Kadereit in Kadereit & Freitag (2011: 72), Dianthus rupicola Bivona Bernardi (1806: 31) subsp. aeolicus (Lojacono 1888: 163) Brullo & Minissale (2002: 539) , Hyoseris taurina Martinoli (1953: 257) and Limonium tenuiflorum ( Gussone 1832: 89) Kuntze (1891: 395) . Therefore, with the addition of Ephedra strongylensis to this list, the degree of biodiversity of this small but interesting satellite islands of the Sicily, is further increased. According to Mercuri et al. (2020), it is interesting to note that for this island the occurrence of Ephedra individuals was recorded in some pollen profiles dating back to the modern era corresponding to the last centuries after the Middle Ages. Basing on this data, it seemed to have a scarce diffusion in the vegetation of the island, as it is currently observable.

Conservation status: − Ephedra strongylensis can be considered a very rare and localized species, recorded only in two locations (Stromboli and Strombolicchio). Based on its narrow distribution and according to IUCN (2012) criteria, the species can be assessed as “Critically Endangered” [CR, B1ab(ii,iii) and B2ab(ii,iii)]. The conservation status was calculated through the GeoCAT (Geospatial Conservation Assessment Tool) programme ( Bachman et al. 2011), which shows an Area of Occupancy (AOO) of 8 km 2. Moreover, the new species fall within a nature reserve named “Riserva Naturale Orientata Isola di Stromboli e Strombolicchio”, as well as in a Special Area of Conservation (SAC ITA030026). In relation to our observations, Ephedra strongylensis can be threatened only by occasional fires or possible lava flows since the island is an active volcano, which could reduce the number of individuals, which are concentrated in two main known populations.

Additional specimens of Ephedra strongylensis examined (Paratypes):— ITALY. Sicily: Isole Eolie, Strombolicchio , sulla sommità, 38°49’01” N, 15°15’06” E, 27 May 2021, D. Azzaro, S . Cambria & V . Ilardi s.n. ( CAT!); Stromboli, Ginostra presso S . Lazzaro , su substrati basaltici, 27. May 2021, D. Azzaro, S . Cambria , V . Ilardi & R . Zaia s.n. ( CAT!); Stromboli, Ginostra presso S . Lazzaro , su substrati basaltici, 15 July 2021, R . Zaia s.n. ( CAT!); Stromboli, Ginostra presso S . Lazzaro , su substrati basaltici, 6 August 2021, S . Cambria s.n. ( CAT!) .

Taxonomic remarks: —From the taxonomical viewpoint, Ephredra strongylensis is rather isolated morphologically from the other currently known Mediterranean species of this genus. This new species shows some relationships mainly with E. aurea , especially in sharing twigs not easily disarticulating at the nodes, finely furrowed and scabrous, leaves opposite, very short and fused for most of their length, turning brown at maturity, female cones uniovulate and pollen grains of type “A”, but significant features hallow to distinguished very well the two species. In particular, E. aurea shows twigs, pedicels of male cones, male cones bracts, synangiophore, synangia, pedicels of female cones, female cones bracts, micropilar tube, fruiting strobilus, and seeds well differentiated from those ones of E. strongylensis (see Tab. 1 ).In addition, they also differ in the seed coat ornamentations, since E. aurea is characterized by very larger cells (170–250 × 28–35 μm) bordered by a prominent reticulum, with periclinal walls flat more or less rugose and anticlinal walls quite raised (see Brullo et al. 2022), while E. strongylensis has smaller cells (16–28 × 4–6 μm) separated by slender grooves, with periclinal walls sligtly convex more or less smooth and anticlinal walls thin and flat. Some differences was observed in the size and shape of pollen grain, since E. aurea has the pollen fusiform acute at the poles (43–48 × 17–20 μm) with 11–12 plicae acute on the back (see Brullo et al. 2022), conversely E. strongylensis has pollen elliptical rounded at the poles (46–50 × 20–27 μm) with 12-16 plicae rounded on the back.

On the basis of field and herbarium investigations, in Sicily there are certainly only 3 species of Ephedra , in addition to that new one here described, they are: E. nebrodensis , E. fragilis , E. aurea and E. strongylensis . Besides, according to literature data ( Conti et al. 2005, Giardina et al. 2007, Pignatti 2017) E. distachya is also recorded from Sicily, according mainly to old reports in sandy coastal areas, where it was probably present in the past, but where it is completely disappeared today, due to anthropogenic factors. It is therefore included in the analytical key that is here provided:

Figures

FIGURE 1. Ephedra strongylensis. A. Twig with female cones. B. Female cones. C. Median longitudinal section of a female cone. D. Habit of a twig with female cones. Illustration by S. Brullo based on living material coming from type locality.

FIGURE 2. Ephedra strongylensis. A. Twig with male cones. B. Male cones. C. Habit of a twig with male cones. D. Male perianth and synangiophore. E. Internode with scale-leaves. F. Detail of internode bark. Illustration by S. Brullo based on living material coming from type locality.

FIGURE 3. Ephedra strongylensis. A. Ripe female cones. B. Seeds. C. Habit of a twig with ripe female cones. Illustration by S. Brullo based on living material coming from type locality.

FIGURE 4. Ephedra strongylensis. A. Habit of a plant with female cones. B. Habit of a plant with ripe female cones. C. Habit of a plant with male cones. Illustration by S. Brullo based on living material coming from type locality.

FIGURE 5. Phenological features of Ephedra strongylensis. A. Stromboli near Ginostra (locus classicus), individual in natural habitat with ripe strobili. B. Strombolicchio, male individual in natural habitat. C. Twigs with male cones. D. Twigs with female cones. E. Detail of a ripe strobilus. cones. F. Twigs with ripe strobili. (Photos by S. Cambria).

FIGURE 6. Twigs of Ephedra strongylensis with leaves

FIGURE 7. SEM micrographs of the seed coats of Ephedra strongylensis: A. Seed at low magnification (× 15). B. Seed testa at medium magnification (× 50). C. Seed testa at high magnification (× 300). From type material (CAT!).

FIGURE 8. SEM micrographs of pollen grain of Ephedra strongylensis A. Equatorial view (x 2000). B. Polar view (x 2000).

FIGURE 9. Distribution map of Ephedra strongylensis (red dots) in Sicily based on herbarium materials.