Greece. Ionian Islands: Nom. Lefkada, Lefkada, Halbinsel Lefkátas, Hangkante über der Westküste WNW ober Aghios Nikólaos Níras (NNE Akr. Dhoukáto, ca. 8 km SSW Atháni), 38°35'43"N, 20°33'06"E, meerseitige Kalkfelsfluren, ca. 230 m elev., 24 May 2000, W. Gutermann et al. 35241 (holotype: WU 0154346; isotypes: ATH, K, M, LD, UPA, herb. Gutermann).

Generis Thliphthisae species nova: suffrutex nanus, laxe aut densius pulvinatus e caudice valde lignoso multicaulis; caulibus scabris, dense et aeque foliatis usque ad apicem; foliis verticillatis quaternis vel senis, leniter crassiusculis, anguste oblanceolatis brevissime apiculatis, modice setosis; floribus solitariis sessilibus; corollis hypocrateriformibus, albis, extus setosis; staminibus in medio corollae inserta, antheris luteis; ovariis ± dense setosis praesertim ad apicem versus, stylo manifeste bifido stigmatibus breviter ellipsoideis. – Chromosomatum numerus 2n = 44, scil. species tetraploidea. Crescit in declivibus apricis saxosis insulae Leucas Graeciae. Floret mense Maio & Junio.

Figure 1. 

Illustration of Thliphthisa sapphus, based on the type material A whole plant B whole plant with vegetative and flowering shoots C vegetative shoot D detail of stem of vegetative shoot E flowering shoot F detail of stem of flowering shoot G flower H dissected flower (drawings by A. Kästner).

Caespitose, suffruticose cushions with lignified rootstock and numerous slender ± short herbaceous shoots, up to 6 cm tall (in cultivation up to 10 cm), internodes scabrous, shorter than leaves (in cultivation somewhat longer), leaves regularly spaced, internodes with retrorse indumentum of minute setose hairs approx. 0.1 mm in length, retrose on vegetative and antrorse on flowering shoots. Leaves and leaf-like stipules in rather closely-spaced whorls of (4–)6, sessile, more or less succulent in life, linear to narrowly oblanceolate, 0.8–1(1.2) × 4–5(7) mm with short-apiculate apex, with sparsely setose margins and lower mid-ribs. Inflorescence terminal, frondose, cymes on short setose peduncles ca. 1–3 mm long, the individual cymes reduced to solitary flowers; flowers sessile, subtended by 4 setose prophylls; calyx reduced; corolla 4-merous, salverform, (crème-)white, externally ± densely setose with patent hairs 0.2–0.3 mm long, internally glabrous, the tube 2.5–3.5 mm long, the lobes ca. 1 mm long; anthers 4, yellow, glabrous, ca. 0,8 mm long, included in the tube, filaments ca. 0,8 mm long, inserted ca. 2/3 of the tube; style glabrous, bifid, the last ca. 0.5 mm free, the 2 stigmas slightly elongated to ellipsoid, included in the tube; ovary ca. 1.3 mm long, apically truncate, ± densely setose especially towards the apex, with patent hairs 0.2–0.3 mm long. Mature infructescence and fruits unknown.

Figure 2. 

Habit and flowers of Thliphthisa sapphus A old individual of Th. sapphus with a thick lignified rootstock B flowers of Th. sapphus exhibiting the characteristic indumentum on the corolla (photographs by M. Sonnleitner).

Due to the chamaephytic habit, with leaves (and leaf-like stipules) in rather closely-spaced whorls of 4–6, the presence of prophylls at the base of the sessile 4-merous flowers and the apically truncate ovary, Thliphthisa sapphus belongs to the subclade of the "Sherardia clade" (Manen et al. 1994; Natali et al. 1995), which is now classified as genus Thliphthisa (Del Guacchio and Caputo 2020). Within this group defined by Schönbeck-Temesy and Ehrendorfer (1985), the new species belongs to a group of chamaephytic taxa with presumably plesiomorphic flower structures, sharing well-developed corolla tubes and slightly elongated (not globose) stigmata. This group comprises Th. crassula (Greuter & Zaffran) P.Caputo & Del Guacchio, Th. tournefortii (Sieber) P.Caputo & Del Guacchio (group A of the former study), Th. baenitzii (Heldr. ex Boiss.) P.Caputo & Del Guacchio and Th. muscosa (Boiss. & Heldr.) P.Caputo & Del Guacchio (group B). Other species with similar flower morphology are xeromorphic subshrubs deviating by their broomrape-like appearance.

Thliphthisa sapphus is most similar to Th. baenitzii, but is readily distinguished by mericarps and corolla being ± densely setose (vs. glabrous), by its longer corolla of approximately 3.5–4.5 mm (vs. 2.5–3.5 mm in Th. baenitzii; Ehrendorfer and Krendl (1976), own measurements; the corolla length of 3–4 mm as given in Schönbeck-Temesy and Ehrendorfer (1985) is erroneous) and, in particular, by its tetraploid chromosome number that so far is unique within Thliphthisa (see below). Thliphthisa muscosa is also similar, but is well differentiated from both by its laxer growth, longer and ± erect flowering stems and distinctly longer, linear leaves.

Additional gatherings (paratypes). Same locality as holotype: 10 November 1994, W. Gutermann et al. 28787 (WU 0154344, herb. Gutermann 28787); 14 July 1996: E. Hörandl 7766 (ATHU, WU 0154343, herb. Gutermann 80000); 26 April 2011: W. Gutermann et al. 39920 (WU 0154345, herb. Gutermann 39920).

To our present knowledge Thliphthisa sapphus is restricted to a small area around the type locality on the western edge of the Lefkátas Peninsula in south-western Lefkada. Restricted distribution is common in the genus Thliphthisa which generally comprises eastern Mediterranean oreophytes distributed east of the Adriatic Sea and reaching the Alborz Mts. of northern Iran (see maps in Schönbeck-Temesy and Ehrendorfer (1985): figs 9–12). Only three species with more derived flower characters (shortened corolla tubes and globose stigmata) occupy larger areas, notably Th. chlorantha (Boiss. & Heldr.) P.Caputo & Del Guacchio and Th. rupestris (Vis.) P.Caputo & Del Guacchio (NW Balkan mountain ranges), and especially Th. purpurea (L.) P.Caputo & Del Guacchio (Balkan Peninsula and Apennines to southern and south-western Alps). Apart from three Iranian species, all other species are scattered around the east Mediterranean Basin and have a more restricted distribution. This is especially true for the taxa that are morphologically most similar to Th. sapphus and that are known only from single mountain stocks: Th. baenitzii on Mt. Patéras and Th. muscosa on Mt. Olympus.

These three Hellenic steno-endemics form the north-western counterpart of the South Aegean Th. tournefortii and its local Cretan relative Th. crassula (the latter two constitute group A of Schönbeck-Temesy and Ehrendorfer (1985)). Thliphthisa tournefortii is a species of peculiar distribution (map in Runemark (1969: 115); Greuter (1971)) that can be associated chorologically with a “mesogaeic” element and, consequently, with a differentiation dating back to the Miocene (Greuter 1970). The same may be assumed for the above-mentioned more northern taxa Th. baenitzii, Th. muscosa and Th. sapphus sharing the more primitive flower structures with Th. tournefortii. The connections between these “sisters” are bridged geographically by another steno-endemic, still undescribed Thliphthisa species (Gutermann et al., in prep.) of Aetolia that, in habit and foliage, approaches the Cretan Th. crassula. Thus, Th. sapphus constitutes the westernmost outpost of this cluster of Greek steno-endemics. They underline the importance of cliffs as refugial habitats for poorly-competitive old chamaephytes (informally referred to as “Old ladies of the rocks”) through the times (as e.g. discussed in Davis (1951) and Snogerup (1971)).

The epithet commemorates Sappho, the most famous poetess of the Classical Hellenic Era and refers to the traditional (though non-historical) believe she suicidally threw herself from the white cliffs of Lefkátas because of unrequited love for beautiful young Phaon. The epithet is in genitive spelling. The genitive in classical Latin also is "Sapphūs", as testified in the poem delivered as "incerti avctoris epistvla Sapphvs ad Phaonem" in Ovid’s Epistolae Heroidum no. 15.

The chromosome number of Thliphthisa sapphus is here determined as 2n = 4x = 44. The base chromosome number of x = 11 was found in all previously investigated representatives of the genus Thliphthisa [i.e. all sub Asperula: Th. chlorantha, Th. muscosa (Faure and Pietrera 1969), Th. purpurea, Th. rupestris (Moore 1982), Th. crassula, Th. tournefortii (Montmollin 1986), Th. baenitzii (Constantinidis et al. 1997), Th. antalyensis (Ehrend.) P.Caputo & Del Guacchio, Th. brevifolia (Vent.) P.Caputo & Del Guacchio, Th. pseudochlorantha (Ehrend.) P.Caputo & Del Guacchio, Th. serotina (Boiss. & Heldr.) P.Caputo & Del Guacchio (Minareci and Yildiz 2011)], as well as in most Rubieae (Kiehn and Berger 2020, 2023). However, except for Th. sapphus, all the investigated taxa of Thliphthisa are diploid. The representative karyotype of Th. sapphus is mostly composed of metacentric and submetacentric chromosomes (Fig. 3), as reported in other Turkish Thliphthisa (formally Asperula sect. Thliphthisa) taxa (Minareci and Yildiz 2011).

Figure 3. 

Mitotic chromosomes and karyotype of Thliphthisa sapphus (2n = 4x = 44). Scale bar: 5 μm.

Flowering of Thliphthisa sapphus commences in May and, by early July, mostly withering or wilted corollas were observed. At this time, mericarps were not developed even in wilted flowers, but some were conspicuously and unusually swollen and infected by parasites, possibly gall midges (Diptera, Cecidomyiidae) as found parasitising on other Rubiaceae taxa in the Mediterranean area (e.g. Simova-Tošić et al. (2000); Skuhravá and Skuhravý (2016); Skuhravá et al. 2020). The plant cultivated in the HBV never developed fertile fruits, thus suggesting self-infertility. However, we have also failed to find fully-developed fruits in situ. The propagation rate of Th. sapphus seems to be very low, as nearly all cushions observed within this area are old plants with a thick lignified rootstock and taproot (of 1 cm ∅ and more) anchored in the rock fissures (Fig. 2A).

It dwells on steep to nearly vertical limestone cliffs facing the sea and is, thus, exposed to westerly winds, either in fissures in solid rock or within a thin regolith cover (Fig. 4). However, these habitats at elevations of 200–230 m a.s.l. border the slightly elevated plateau of the Peninsula and show no marked salt influence. Whereas large parts of the plateau are dominated by low Quercus coccifera L. garrigue, areas with shallower and rockier soils, especially along the upper slope of the coastal cliffs, are covered by sclerophyllous phrygana vegetation with Anthyllis hermanniae L., Erica multiflora L., Juniperus phoenicea subsp. turbinata (Guss.) Nyman or Thymbra capitata (L.) Cav. Depending on the distribution of narrow rock ledges, erosion fissures/crevices and compact rock, the phrygana forms an intricate mosaic with sparse chasmophytic vegetation. As demonstrated by the vegetation relevés (Table 1), Thliphthisa sapphus is accompanied by another long-lived and cushion-forming chasmophyte Lomelosia crenata subsp. dallaportae (Boiss.) Greuter & Burdet showing scattered occurrences along the western coasts of the southern Ionian Islands (Flora Ionica Working Group 2016 onwards) and having also few isolated populations in Apulia (Italy) on Monte Gargano (Wagensommer 2012). Usually, together with Plocama calabrica (L.f.) M.Backlund & Thulin (Rubiaceae), they form a particular plant community covering the rock fissures.

Figure 4. 

Habitat and habit of Thliphthisa sapphus A coastal cliffs of the Lefkátas Peninsula, the locality of Th. sapphus (photograph by M. Hofbauer) B cushion of Th. sapphus in limestone rock fissure (photograph by M. Sonnleitner) C loose cushion of Th. sapphus within regolith cover on limestone rocks, together with Lomelosia crenata subsp. dallaportae (photograph by M. Sonnleitner).

We here describe this community as a new association, the Thliphthisa sapphus-Lomelosietum dallaportae Mucina ass. nova hoc loco (holotype: relevé 9 in Table 1) and classify this association tentatively in the Caro multiflori-Aurinion megalocarpae Terzi et D’Amico 2008, an alliance of thermo-mesomediterranean chasmophytic vegetation of limestone rock crevices of the south-eastern Italian Adriatic (Apulia) and Ionian coasts (see Mucina et al. (2016)). The syntaxonomic unit floristically and ecologically most similar is the Scabiosetum dallaportae Bianco et al. 1988 (see Bianco et al. (1988): table 4; Di Pietro and Wagensommer (2008: 198), table 3), an association described from Apulia, yet classified within the Asperulion garganicae Bianco et al. 1988 (for the syntaxonomic discussion of the Caro multiflori-Aurinion megalocarpae and the Asperulion garganicae, see Di Pietro and Wagensommer (2008)).

In the area directly accessible to us, we counted about two dozen mature individuals of Thliphthisa sapphus. Within the range of sight, further cushions were identified in the nearly vertical cliff slopes below. The size of this single known population can be estimated at roughly 100 individuals, although more populations may exist in the inaccessible cliffs continuously extending north and south of the known population. In 2011, a few individuals were also found in Erica L. phrygana above the slopes and established on the gravelly banks along a close-by road above the primary cliff habitat. The occurrence on competition-free road banks suggests some potential of the species to colonise open anthropogenic sites, for which an occurrence in unstable gravelly habitats may have been a pre-adaptation.

Due to the restricted known geographic range, the number of individuals may be drastically reduced by natural hazards, such as land or rock slides. The population is not exposed to immediate synanthropic threats, except for goats that graze even the steepest rock declivities such as the less precipitous slopes. Due to the small number of recorded individuals distributed within a range much less than 1 km², the species falls into IUCN criterion D. Taking into account the possible threats mentioned above, it should be assessed as “Vulnerable” D2 (see IUCN (2022)). At national or regional scale, it classifies as a range-restricted endemic (as “r” in Dimopoulos et al. (2013)) and needs to be included in the “Red Data Lists” for Greece as “Endangered”. Further monitoring of the population is certainly needed and conservation measures, such as reduction of grazing, should be taken for the subpopulation in the accessible area at the plateau above the ridge.