Silene melitensis Brullo, C. Brullo, Cambria, Lanfr., S. Lanfr., Miniss., Sciandr. & Giusso, 2017

Brullo, Salvatore, Brullo, Cristian, Cambria, Salvatore, Lanfranco, Edwin, Lanfranco, Sandro, Minissale, Pietro, Sciandrello, Saverio & Galdo, Gianpietro Giusso Del, 2017, A new species of Silene sect. Dipterosperma (Caryophyllaceae) from Malta, Phytotaxa 297 (3), pp. 245-256 : 246-254

Silene melitensis Brullo, C. Brullo, Cambria, Lanfr., S. Lanfr., Miniss., Sciandr. & Giusso , sp. nov. ( Figs. 1 – 2 )

Type: ― MALTA. Gozo: Xlendi Tower, praticelli effimeri, 9 March 2014, Brullo, Lanfranco, Minissale & Sciandrello s.n. (holotype CAT!, isotypes CAT!).

Diagnosis:― A Silene crassiuscula differt scapis ramificatis ad basim, internodiis inferioribus usque ad 4 cm longis, foliis oblanceolatis vel late spathulatis, rotundatis vel obtusis apice, pedicellis floribus 2–8(–10) mm longis, calice 11.5–12.5 mm longo, tomentoso–hirsuto, dentibus 1.3–1.6 mm latis base, petalis 12.0– 13.5 mm longis, limbo petalorum 6.5–7.0 mm longo, lobis petalorum obovato–spathulatis, minoribus, ungue minore, squamis coronulae undulatis inferne, brevioribus, anthera roseo–liliacea, 1.6–1.8 mm longa, ovario 2.2–3.0 mm longo, capsula breviora, carpophoro breviore et seminibus majoribus.

Description:―Annual herb 10–25 cm tall, green, sometimes purple colored, prostrate–ascending, with stems very branched at the base, densely pilose–pubescent (hairs 0.2–0.6 mm long). Lower internodes 5–40 mm long, upper ones 15–60 mm long. Leaves flat, oblanceolate to widely spathulate (15–45 × 5–17 mm), moderately succulent, rounded to obtuse at the apex, shortly petiolate, 1–nerved. Inflorescence lax, (1–2–3(– 5)–flowered. Bracts lanceolate, 3–10 mm long. Flowers erect, arranged in terminal helicoid monochasia. Pedicels 2–8(– 10) mm long. Calyx 11.5–12.5 mm, tomentose–hirsute, subtubulose, purplish–green, 10–nerved, without anastomoses; teeth 2.5–2.7 × 1.3–1.6 mm, ovate–triangular, obtuse, with margin membranous, ciliate at margins. Petals 12–13.5 mm long; limb 6.5–7.0 mm, deeply two–lobed, purplish–pink, with lobes obovate–spathulate (4.8–5.2 × 2.2–2.7 mm), smooth; coronal scales 1.5–1.8(– 2.0) mm, white above and green below, deeply retuse, undulate below; claw 6–7 mm, white, 1–nerved, on the back minutely pubescent along the midrib. Stamens shorter than petals with filament 6.5–9.0 mm long, white and anthers pink–lilac, 1.6–1.8 mm long. Ovary 2.2–3.0 mm, glabrous, green. Styles 3, filiform. Capsule 7.5–8.0 mm, ovoid. Carpophore 4.5–5.2 mm, pubescent. Seeds 1.5–1.7 mm in diameter, dark brown, orbicular–reniform, flat laterally, winged and deeply canaliculate dorsally, and with wings undulate.

Seed micro-morphology:―On the basis of literature ( El-Oqlah & Karim 1990, Hosny & Zareh 1993, Villa 1995, Yildiz & Cirpici 1998, Hong et al. 1999, Yildiz 2006, Perveen 2009, Fawzi et al. 2010, Ocaña et al. 2011, Brullo et al. 2012, 2014a, 2014b, 2015a), seed testa ornamentations have significant implications as concerns the taxonomy of Silene , mainly at specific and infrageneric ranks. Furthermore, it should be noted that seed microsculptures, as constant morphological features, may be used as a further character in the differentiation of the various species, as well as in delimiting the sections.

Silene melitensis shows significant micro-morphological seed differences in comparison with S. crassiuscula and S. nummica (see e.g., Villa 1995, Brullo et al. 2015a, 2015b). Actually, the seeds of S. melitensis ( Fig. 3A ) have similar shape to the two above mentioned species but a larger diameter (1.5–1.7 mm vs. 1.3–1.4 for S. crassiuscula , and 1.0–1.2 for S. nummica ). Seeds are also flat but concave in the center, winged and deeply canaliculate dorsally, besides the wings are more or less undulate as in S. crassiuscula , while in S. nummica they are never undulate. Several micro-morphological features allow to distinguish very well the seeds of S. melitensis from the latter two species. The seed coat of S. melitensis (lateral surface, Fig. 3B ) is characterized by very elongated epidermal cells (100–200 × 20–37 μm), with numerous and spaced tubercles arranged along a central line and regularly lobate-undulate at the margin. The tubercles are densely granulate, while the rest of the outer periclinal wall is laxly and irregularly granulate. The anticlinal walls are very thin and raised with quite regular S-like undulations. At the bottom of the dorsal furrow ( Fig. 3C, D ), the epidermal cells have an elongated shape (80–160 μm long), and they are covered by scattered tubercles with very different size. The anticlinal walls have V–like and very close together undulations.

Etymology: ––The specific epithet refers to the Latin “Melita”, old name of Malta archipelago where this species grows.

Phenolgy: ––Flowering time March–April, fruiting time April–May.

Distribution and ecology: –– Silene melitensis grows on dry stands along the calcareous rocky coast of Maltese archipelago (central Mediterranean basin). It is usually localized on flat surfaces with limestone outcrops covered by a very thin layer of soil and featured by marked halo - xeric edaphic conditions. The new species is a member of a annual plant community ( Fig. 4 ) characterized, for instance, by Anthemis urvilleana Sommier & Caruana (1915: 178) , Catapodium balearicum ( Willkomm 1890: 184) Scholz (2000: 96) , Parapholis incurva ( Linnaeus 1753: 1051) Hubbard (1946: 14) , Silene sedoides Poiret (1798: 164) , Plantago coronopus Linnaeus (1753: 115) , Romulea melitensis Bèguinot (1907: 327) . In the Maltese Archipelago, this species is usually replaced in synanthropic and sandy habitats by S. colorata , which is widespread all over the islands. As concerns its distribution, S. melitensis occurs in several localities of Gozo and Malta ( Fig. 5 ).

Conservation status: –– Silene melitensis shows a distribution restricted to few stands of the Maltese Archipelago, where it is always represented by small populations, usually not exceeding some hundred individuals. Besides, being exclusive of coastal habitats under severe anthropogenic pressures, the species may be subject to a progressive impoverishment of its populations. According to the IUCN criteria ( IUCN 2014), S. melitensis may be assessed as “Vulnerable” [VU, criterion B2ab(ii+iii)].

Taxonomic remarks:–– According to Brullo et al. (2015b), S. nummica and S. crassiuscula are well differentiated from the other species belonging to Silene sect.Dipterosperma by some significant diagnostic characters, and particularly for the leaves which are moderately succulent and not thin. This feature is also detected in S. melitensis which similarly to the previous cited species grows in rocky places near the sea. On the basis of the results obtained in the present work, S. melitensis seems to be more related with S. crassiuscula , mainly for the bigger size, few-flowered inflorescences (rarely 1-flowered), calyx teeth ovate-triangular and obtuse, petal claw pubescent in the midrib, seed wings undulate. Whereas, it differs from both species for the longer internodes, shorter pedicels, petals, ovary and carpophore and larger seeds ( Table 1). As concerns S. nummica , this species shares with S. melitensis the stems branched at the base, calyxes tomentose-hirsute, petal lobes obovate-spathulate and smaller, while it differs in having flower solitary, petal with limb larger and claw totally hairy on the back, capsule smaller, carpophore longer and seed with wings flat. Other relevant differences regard the seed coat ornamentations, which allow to distinguish very well these three species (Tab.9). Therefore, since these species showing close relationships and similar ecological requirement, it is possible presume that the speciation processes were favored by their geographic isolation.

Identification key to the species belonging to Silene sect. Dipterosperma :–– It follows:

1. Carpophore less than 4 mm ................................................................................................................................................................2

- Carpophore more than 4 mm ..............................................................................................................................................................3

2. Carpophore 0.5–1.5(–2.5) mm long. Calyx 6–9 mm long. Petal rudimentary or absent, rarely with limb up to 3 mm long.............. .............................................................................................................................................................................................. S. apetala

- Carpophore 1.5–4.0 mm long. Calyx 10–13 mm long. Petal well developed with limb 6–10 mm long............................ S. gracilis

3. Calyx with nerves markedly anastomosed ................................................................................................................... S. secundiflora

- Calyx with nerves not anastomosed...................................................................................................................................................4

4. Calyx 18–22 mm long........................................................................................................................................................................5

- Calyx 10–16 mm long........................................................................................................................................................................6

5. Flowers solitary. Leaves lanceolate, sericeous. Capsule 10–11 mm long. Carpophore 12–14 mm long............................. S. sericea

- Flowers arranged in monochasia. Leaves spathulate, setose. Capsule 8–9 mm long. Carpophore 7–8 mm long .......... S. morisiana

6. Petal with limb lobes 1.5–2.0 mm wide ......................................................................................................................... S. kemoniana

- Petal with limb lobes more than 2 mm wide......................................................................................................................................7

7. Stems erect (rarely erect-ascending)..................................................................................................................................................8

- Stems prostrate–ascending...............................................................................................................................................................11

8. Stems branched at the nodes. Leaves linear to linear-lanceolate. Calyx 10–12 mm long. Capsule 5–6 mm long ......... S. beguinotii

- Stems branched at the base. Leaves lanceolate to spathulate. Calyx 12–14 mm long. Capsule 6–8 mm long..................................9

9. Leaves linear-spathulate. Inflorescence 4–10-flowered. Petals 13–15 mm long ............................................................... S. colorata

- Leaves lanceolate. Inflorescence 2–5-flowered. Petals 16–20 mm long..........................................................................................10

10. Calyx teeth acute, 3.8–4.5 mm long. Petals 18–20 mm long. Carpophore 7–8 mm long. Seed 1.5–2.0 mm in diameter................... ......................................................................................................................................................................................... S. arghireica

- Calyx teeth obtuse, 1.0– 1.5 mm long. Petals 16–17 mm long. Carpophore 5–6 mm long. Seed 1.0– 1.5 mm in diameter................. ......................................................................................................................................................................................... S. canescens

11. Stem 40–60 mm long, with internodes up to 8 cm long. Leaves pinnately-nerved. Calyx teeth acute, 2.8–3.6 mm long. Petal 18–19 mm long. Petal lobes 8.0– 8.5 mm long. Capsule 9–10 mm long. Seed 2.0– 2.2 mm in diameter...................................... S. nefelites

- Stem 5–25 mm long, with internodes up to 4.5 cm long. Leaves 1-nerved. Calyx teeth obtuse to rounded, 1.2–2.8 mm long. Petal 14–17 mm long. Petal lobes 3.0– 6.5 mm long. Capsule 4.5–8.0 mm long. Seed 1.0– 1.5 mm in diameter.....................................12

12. Leaves thin, obtuse. Calyx 8–11 mm long, with teeth 1.2–1.8 mm long. Petal limb 6–7 mm long, with lobes 3–4 mm long. Carpophore 3.5–4.5 mm long.................................................................................................................................................... S. peloritana

- Leaves succulent, rounded to obtuse. Calyx 11–15 mm long, with teeth 2.0– 2.8 mm long. Petal limb 7.5–10.0 mm long, with lobes 5.0– 6.5 mm long. Carpophore 5.0– 6.5 mm long..............................................................................................................................13

13. Stems branched at the nodes. Calyx minutely pubescent. Petal lobes spathulate, 6.0– 6.5 mm long........................... S. crassiuscula

- Stems branched at the base. Calyx tomentose-hirsute. Petal lobes obovate-spathulate, 4.8–5.5 mm long......................................14

14. Flower solitary. Petal 14–15 mm long, with limb 7.5–8.0 mm long and claw totally hairy on the back. Capsule 4.5–6.5 mm long. Carpophore 6.0– 6.5 mm long. Seed with wings flat ......................................................................................................... S. nummica

- Inflorescence (1–)2–3(–5)-flowered. Petal 12.0– 13.5 mm long, with 6.5–7.0 mm long and claw pubescent in midrib. Capsule 7.5–8.0 mm long. Carpophore 4.5–5.2 mm long. Seed with wings undulate .................................................................. S. melitensis

Additional specimens examined of Silene melitensis (paratypes): ― MALTA. Malta: Miġra l-Ferħa ( Mthaleb ), costa rocciosa, 29 March 2016, Cambria s.n. ( CAT!) ; Malta: Miġra Ferħa , low cliff top garrigue, 15 April 2014, Lanfranco s.n. (Herb. E. Lanfranco) ; Malta: Ghadira grassy ground & garrigue near the sea, 25 January 1970, Lanfranco 794 ( Herb. E. Lanfranco!). Malta: Golden Bay , 12 April 1984, Brullo & Ronsisvalle s.n. ( CAT!) ; Malta: Malfa, Armer Bay , 11 April 1987, Brullo, Pavone & Ronsisvalle s.n. ( CAT!) ; Gozo: pianoro sopra Sanap Cliffs , presso Munxar, 27 March 2016, Cambria s.n. ( CAT!) ; Gozo: pianoro sopra Seguna Cliffs , presso Sannat, 27 March 2016, Cambria s.n. ( CAT!) ; Gozo: Xlendi Tower , pianoro roccioso, 27 March 2016, Cambria s.n. ( CAT!) ; Gozo: Cala Dwejra , costa rocciosa, 27 March 2016, Cambria s.n. ( CAT!) ; Gozo: Ta’ Cenc , low cliff top garrigue, 9 April 2014, Lanfranco s.n. ( CAT!) ;

Specimen examined of S. colorata : ― MALTA. Malta : incolti presso Wardija, 29 March 2016, Cambria s.n. ( CAT!) ; Malta: Wied Hal-Sabtan (Birzebbugia), 29 March 2016, Cambria s.n. ( CAT!) ; Gozo: incolto presso Ghammar, 26 March 2016, Cambria s.n. ( CAT!) ; Gozo: incolto presso l’abitato di Xlendi, 27 March 2016, Cambria s.n. ( CAT!) ; Gozo: dune di Ramla Bay, 26 March 2016, Cambria s.n. ( CAT!) ; Malta: Ghadira arid localities, 1 May 1968, Lanfranco 893 (Herb. E. Lanfranco!) ; Malta : Il Qaliet near Dragonara, disturbed maritime garrigue, 9 May 2014, Lanfranco s.n. ( CAT!) ; Malta: Qalet Marku , low maritime garrigue, 4 April 2014, Lanfranco s.n. ( CAT!) ; Malta: Buskett , inland garrigue, 5 May 2014, Lanfranco s.n. ( CAT!) ; Malta: Ta’ Laroka low garrigue, 6 May 2014, Lanfranco s.n. ( CAT!) ; Malta: Wied il-Kbir, 1 November 1969, Lanfranco 891 (Herb. E. Lanfranco!) .

Figures

FIGURE 1. Silene melitensis. A. Habit. B. Basal leaves. C. Cauline leaves (drawing by S. Brullo based on living material coming from the type locality, CAT).

FIGURE 2. Silene melitensis. A. Flower (lateral view). B. Flower (above view). C. Open calyx. D. Calyx teeth. E. Petal with stamens (ventral view). F. Petal with stamen (dorsal view). G. Coronal scale. H. Anther (ventral view). I. Anther (dorsal view). J. Pistils. K. Capsule close with calyx. L. Capsule open with calyx. M. Capsule close with carpophore. N. Capsule open with carpophore. O. Seed (lateral view). P. Seed (dorsal view) (drawing by S. Brullo based on living material coming from the type locality, CAT).

FIGURE 3. SEM micrographs of seed testa of Silene melitensis A. Seed (lateral view) at low magnification (x 35). B. Seed coat detail (lateral view) at high magnification (x 500). C. Seed (dorsal view) at low magnification (x 60). D. Seed (dorsal view) at high magnification (x 100).

FIGURE 4. Silene melitensis from type locality (Xlendi, Gozo). A. Habitat. B. Habit. C. Detail of leaves. D. Detail of flower (lateral view). E-F. Detail of flower (view from above). G. Fructiferous calyx. Photo by S. Sciandrello (A, B,E, F, G) and by S. Cambria (C, D).

FIGURE 5. Geographical distribution of Silene melitensis (black dots), based on herbarium specimens.