Micromeria silicii Bogdanović, Ljubičić, L. Sáez & Brullo, 2024

Bogdanović, Sandro, Ljubičić, Ivica, Sáez, Llorenç & Brullo, Salvatore, 2024, Micromeria silicii, a new species from Croatia and its relationships with taxa of the M. microphylla group (Lamiaceae), Phytotaxa 662 (1), pp. 1-18 : 3-7

Micromeria silicii Bogdanović, Ljubičić, L. Sáez & Brullo sp. nov. ( Fig. 1 )

A Micromeria microphylla foliis crassiusculis, indumento breviore, pedicello 1–1.6 mm longo, pilis 0.1–0.2 longis, calyce 3–3.7 mm longo, tubo pilis incurvis 0.05–0.2 mm longis, dentibus superioribus 0.6–0.8 mm longis, corolla 3.5–4 mm longa, fauce sparsim pilosa, labio superiore 0.6–0.8 mm longo, 0.8–1 mm lato, labio inferiore 0.8–1.3 mm longo, 1–1.2 mm lato, non exertis staminibus, filamentis staminorum superiorum 0.4–0.5 mm longis, stylo 1.1–1.5 mm longo, nucula 0.8–1 x 0.4–0.5 mm, differt.

Type:— CROATIA. Dalmacija, otok Biševo, Rt Gatula, rub strmaca, u stijeni, 1 June 2020, 42°57’18,30”N, 15°59’51,84”E, S. Bogdanović s.n. (holotype ZAGR 58964!, isotypes CAT!, ZAGR!).

= M. graeca Bentham var. pauciflora Visiani (1847: 196) . Type:— CROATIA. Ad rupes maritimas scopuli S. Andrea prope Lesina, Stalio 1358 (PAD-HD04822!), lectotype designated here (upper specimen).

Description:—Dwarf, suffruticose, 8–20 cm tall, with compact and robust caudices, provided with several simple slender stems, procumbent to ascending, sometimes erect, densely pubescent with patent or retrorse short hairs, 0.1– 0.3 mm long. Stem internodes 2–4 mm long, basal ones rarely up to 13 mm long, with opposite leaves, provided with hairs 0.1–0.3 mm long. Lower leaves fleshy, subsessile, ovate to ovate-cordate, 2.5–6 × 2–4.5 mm, acute at the apex, with thickened margin, sometimes slightly revolute, 3–4 nerved, sparsely hairy and shiny on adaxial side, densely hairy and glandular on abaxial side, hairs appressed to patent, 0.1–0.5 mm long, with prominent veins, median and upper leaves lanceolate to linear-lanceolate, 2.5–4.4 × 0.9–1.5 mm. Inflorescence terminal, quite compact, 2.5–5 cm long, verticillasters of 2 pedunculate fascicles, each 1–3-flowered; peduncles up to 1–2 mm long, bracts lanceolate, 1–2 mm long. Flower pedicel 1–1.6 mm long, with hairs 0.1–0.2 mm long. Calyx 3–3.7 mm long, with tube covered by curved hairs 0.05–0.2 mm long, teeth covered with right hairs, 0.2–0.4 mm long, lower teeth long lanceolate, 1.1–1.5 mm long, upper teeth triangular, 0.6–0.8 mm long. Corolla pale pink, 3.5–4 mm long, tube exerted from the calyx, with a throat sparsely hairy, upper lip 0.6–0.8 mm long, 0.8–1 mm wide, retuse at the apex, lower lip 0.8–1.3 mm long, 1–1.2 mm wide, trilobed. Stamens included in corolla, or slightly exerted, upper filaments 0.4–0.5 mm long. Style 1.1–1.5 mm long, with bifid stigma, 0.2–0.3 mm long. Mericarps ovoid, blackish, 0.8–1 × 0.4–0.5 mm, beaked at the apex, convex dorsally, ventrally with two hollows.

Iconography: —Tab. 58 in Šilić (1979).

Distribution and ecology: —Based of herbarium and field investigations, M. silicii is currently known from the island St. Andrea (Svetac) and Biševo, belonging to the Vis Archipelago in Croatia ( Fig. 2 ). It is a very rare species occurring in few stands of these two islands, where it is localized on calcareous outcrops near the shoreline ( Fig. 3 A–F ). In these places it grows together with other endemic chasmophytes, such as Centaurea ragusina Linnaeus (1753: 912) , Cynanchica staliana ( Visiani 1850: 11) P.Caputo & Del Guacchio in Del Guacchio & P.Caputo (2020: 775), Cynanchica visianii ( Korica 1979: 72) P.Caputo & Del Guacchio in Del Guacchio & P.Caputo (2020: 776), Limonium busianum Bogdanović & Brullo (2015: 11) , L. zankii Bogdanović & Brullo (2015: 28) and Micromeria kerneri Murbeck (1892: 53) . Besides, other species are also frequent among them Convolvulus cneorum Linnaeus (1753: 157) , Silene sedoides Poiret (1789: 164) , Helichrysum italicum (Roth 1790: 19) G. Don (1830: 342) , Daucus gingidium Linnaeus (1753: 242) , Erica multiflora Linnaeus (1753: 355) , Rosmarinus officinalis Linnaeus (1753: 23) and others.

Etymology: —This species is dedicated to the botanist Čedomil Šilić (1937–2010), who studied the genus Micromeria for the Balkan flora.

Phenology: —It flowers from May to early July, and fruits from late June to July.

Remarks: —Even when an epithet is available as an infraspecific synonym, that is in our case Micromeria graeca var. pauciflora , it has no priority out of its rank, according to Art. 11.2 of the ICN ( Turland et al. 2018). Further, in the protologue of M. graeca var. pauciflora ( Visiani 1847: 196) there is a note referring to M. pauciflora as an annotated name in herbarium specimen by Visiani, that is not formally published and therefore we prefere to use a new name ( Micromeria silicii ) for this Adriatic endemic species. As concerns its relationships with the other species of M. microphylla group ( Table 1), M. silicii is more similar to M. microphylla s. str., since both share a habit procumbent to ascending, dimorphic leaves, the basal ones ovate to cordate, the upper ones lanceolate to linear-lanceolate, verticillaster always few flowered (1–3), but several diacritic features allow to differenciate them very well. In particular, M. silicii shows stems always simple, covered by shorter hairs (0.1–0.3 mm long), patent to retrorse, calyx longer (3–3.7 mm long), with hairs shorter (0.05–0.4 mm long), markedly bilabiate, with upper teeth many shorter than lower ones, corolla shorter (3.5–4 mm long), with tube included in the calyx, stamens included in the corolla tube, mericarps bigger (0.8–1 × 0.4–0.5 mm). On contrary, M. microphylla is characterized by stems simple to branched, covered by longer hairs (0.3–0.8 mm long), patent to reflexed, calyx shorter (2.5–3.2 mm long), slightly bilabiate, with upper teeth a little shorter than lower ones, corolla longer (4.5–6 mm long), with tube long exserted from the calyx, stamens exserted from corolla tube, meriarps smaller (0.6–0.8 × 0.3–0.4 mm). Individuals collected on St. Andrea Island and attributed to M. microphylla were used for molecular study by Kremer et al. (2022) that show a genome very similar to that one of M. kerneri . From the observation of the photo of this material ( Fig. 6 Mm) published previously by those authors ( Kremer et al. 2021), its identification is clearly incorrect, since it corresponds to M. kerneri for the erect stems, all linear leaves and dense vericillasters similar to the plant shown on Fig. 6 Mk. From this, it can be deduced that a specimens of M. kerneri were collected by the authors instead of M. microphylla , both species occurring on the island of St. Andrea ( Pavletić 1978), justifying its phylogentic position in the neighbour-joining tree shown in Kremer et al. (2022: Fig. 1 ). As concerns the morphological affinities of M. silicii with the other species of this group it must be emphasized that M. acropolitana differs from the latter in having stem erect and branced with reflexed hairs, leaves cordate-lanceolate to oblong-lanceolate, 0.4–1.5 mm wide, verticillaster up to 5(–7)-flowered, calyx smaller (2.4–2.5 mm long), with subequal teeth (0.6–0.8 mm long), covered by hairs 0.5 mm long, corolla smaller. Micromeria carpatha is well differentieted from M. silicii by longer size, with stem subglabrous and very branched, leaves scabrid, the basal one cordate lanceolate, up to 2.4(–3) mm wide, corolla shorter, stamens exserted from the tube, mericarps smaller (up to 0.6 mm long). Micromeira sphaciotica differs in stems often branched, with hairs up to 0.8 mm long, leaves uniformelly ovate to lanceolate, not more than 2.5 mm wide, verticillaster up to 5-flowered, calyx usually 2.5–3 mm long, lower teeth shorter (0.9–1 mm long), corolla longer (5–6 mm long), with tube long exerted from the calyx. Micromeria hispida in comparison with M. silicii differs in stem simple or branched covered by longer hairs (0.4–0.7 mm long), leaves ovate to lanceolate, narrower (max. 2.4 mm wide), calyx longer (4.5–5 mm long), covered by longer hairs (0.4–0.8 mm long), with upper teeth longer (1.2–1.5 mm long) and also lower teeth (1.6–2.2. mm long), corolla longer (5–6.5 mm long), with tube exserted from the calyx and stamens slightly exserted from the corolla tube. As concerns M. cypria it is characterized by higher stem, ascending to erect, usually branched, leaves up to 9 mm long, verticillaster often more flowered (up to 7 flowers), longer corolla (5–5.5 mm long), long exserted fom the calyx, stamens exserted from the corolla tube, mericarps smaller (0.7 × 0.4 mm). Finally, M. rodriguezii is well differentiated in having stems always covered by retrorse hairs, leaves more or less uniform, verticillaster 2–5 flowered, calyx up to 4(–4.5) mm long, with teeth subequal, 0.8–1.7 mm long, corolla longer (5–6.5 mm long), and slightly exerted from the calyx.

Additional examined specimens (paratypes):— CROATIA. Dalmacija, otok Svetac, uz kuće kamenjar uz put, 43°1’21,13”N, 15°45’29,81”E, 26 July 2018, S. Bogdanović s.n. ( ZAGR 48168 !, ZAGR 48169 !) ; Dalmacija, otok Biševo, Trešjavac vršni plato, na rubu litica, 42°57’37,15”N, 16°0’13,37”E, 26 May 2016, S. Bogdanović & I. Ljubičić s.n. ( ZAGR 42838 !, ZAGR 42821 !) ; o. Svetac kod Visa, 10–20 m elevation, (iznad abrazione zone valova), (kod crkvice Sv. Andrija), solo calc. & dol., 25 June 1978, Č. Šilić s.n. ( LJU 10094309 !, SARA!, WU 0150208 !) ; Insel San Andrea westl. von Lissa: Oberhalb Porto Slatina, 6–9 June 1911, A. Ginzberger & A. Teyber s.n. ( WU 0150206 !) .

Figures

FIGURE 1. Micromeria silicii. A. Habit. B. Branch with inflorescences. C. Stem indumentum. D. Cymes. E. Cyme peduncle. F. Open calyx dorsal view. G. Open calyx ventral view. H. Open corolla ventral view. I. Stlyles and stigmas. J. Leaves abaxial face. K. Leaves adaxial face. L. Mericarps. Illustration by S. Brullo based on living material coming from Biševo Island (type locality) in Croatia.

FIGURE 2. Distribution map of species belonging to Micromeria microphylla group based on herbarium materials: M. silicii (red dots), M. microphylla (black dots), M.rodriguezii (green dots), M. acropolitana (blue dot), M. sphaciotica (yellow dot), M. hispida (orange dots), M. carpatha (pink dot) and M. cypria (purple dots).

FIGURE 3. Phenological features of Micromeria silicii. A. Biševo Island, Cape Gatula (locus classicus), natural habitat. B–C. Habit in natural places. D. Detail of the inflorescence. E–F. Detail of the inflorescence with corolla. G. Habit of M. microphylla from Sicily. H. Detail of the inflorescence with corolla from Sicily. (Photos A–F by S. Bogdanović, G–H by S. Cambria).

FIGURE 6. Micromeria rodriguezii. A. Habit. B. Branch with inflorescences. C. Cymes. D. Stem indumentum. E. Calyx. F. Leaves abaxial and abaxial face. Illustration by L. Sáez based on material coming from Balearic Islands, Mallorca, Palma, Génova (BC 49863).