Cynanchica paphlagonica Tunçkol & Trigas, 2025

Tunçkol, Bilge, Liveri, Eleni, Koumandou, Vassiliki Lila, Aksoy, Necmi, Yaşayacak, Hasan & Trigas, Panayiotis, 2025, Cynanchica paphlagonica (Rubiaceae, Rubieae), a new species from Türkiye based on morphology and phylogenetic data, Phytotaxa 704 (1), pp. 35-48 : 37-43

Cynanchica paphlagonica Tunçkol & Trigas , sp. nov. ( Figs. 1 , 2 )

Type:— TÜRKIYE. Kastamonu: PInarbaŞI District, Küre Mountains National Park , Horma Canyon , limestone rocks and cliffs, 41°38’ N, 33°08’ E, 690 m a.s.l., 20 May 2020, B. Tunçkol 5794 (holotype DUOF0011340 ; isotype ACA0012805 ) .

Cynanchica paphlagonica is similar to C. stricta , but differs by being a delicate, densely caespitose plant (versus ± robust, loosely caespitose), with inflorescence consisting of 1–2(–3) verticillasters (versus (1–)2–8 verticillasters), corolla pale yellow (versus pink, greenish- or brownish-yellow), and mericarps 1.2–2 mm long (versus 2–3 mm long). Cynanchica paphlagonica is further distinguished from all individual subspecies of C. stricta by additional morphological characters.

Description:—Delicate, densely caespitose, bright green plant with a slender woody rootstock and numerous vegetative shoots. Flowering stems numerous, slender, quadrangular, 5–20 cm long and 0.2–0.4 mm thick, erect or ascending, unbranched, sparsely minutely scabridulous at the base, glabrous above. Leaves green, filiform, 4-whorled, 5–10 × 0.3–0.7 mm, densely clustered on vegetative shoots and at the bases of flowering stems, glabrous except the ± scabridulous basal leaves, terminate in a hyaline mucro 0.1–0.2 mm long, margins revolute, midrib prominent beneath, 1/4–1/2 as broad as leaf. Inflorescence spiciform, consisting of 1–2(–3) verticillasters, each bearing 2–6 sessile or shortly pedicellate flowers; bracts 1.5–4 mm long, linear to lanceolate, free to the base, with a narrow hyaline margin, typically forming two distinctly unequal pairs; bracteoles 1.5–3 mm long, lanceolate to narrowly ovate, free to the base, bordered by a narrow hyaline margin. Corolla pale yellow, hypocrateriform, 7–10 mm long, glabrous; lobes recurved, 1/3–1/4 as long as tube, oblong-lanceolate, minutely appendiculate. Ovary papillose throughout or in the distant half only. Mericarps ellipsoid, 1.2–2 mm long, tuberculate.

Phenology: —Flowering in May, fruiting in July and August.

Distribution and habitat:— Cynanchica paphlagonica is currently known from a single locality in Kastamonu Province, PInarbaŞI District, Çiçekli neighbourhood, Günberi location, N Türkiye ( Fig. 3 ). It grows in crevices of limestone cliffs and rocky slopes, accompanied by other interesting taxa, such as Allium rupestre Steven (1812: 260) , Arabis caucasica Willdenow (1814: 45) , Arenaria filicaulis Fenzl in Grisebach (1843: 203) subsp. filicaulis, Buxus sempervirens Linnaeus (1753: 983), Globularia cordifolia Linnaeus (1753: 96) , Saxifraga rotundifolia Linnaeus (1753: 403) , Scilla bithynica Boissier (1846: 111) , Sideritis dichotoma Huter (1907: 360) , etc.

Etymology:—From Paphlagonia, the ancient name of the region on the Black Sea coast of NC Anatolia that includes the present day Kastamonu Province, where the new species has been discovered.

Molecular phylogenetic analysis: —The total length of the analyzed sequences was 1656 bp including 1280 conserved sites, 257 variable sites and 63 parsimony informative sites. Maximum Likelihood phylogenetic analysis revealed a poorly resolved topology, whereas Bayesian analysis resulted in a tree with better resolution. In Fig. 4 the Bayesian phylogram is shown and the branches which are also supported by ML analysis are indicated. The overall topology is in accordance with Gargiulo & al. (2015). In particular, the new species is found in a polytomy (pp =0.99, BS=61%) with other six taxa: C. nitida (Smith in Sibthorp & Smith 1806: 89) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 773) subsp. nitida , C. stricta subsp. latibracteata (Boissier 1875: 35) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 775), C. stricta subsp. grandiflora (Schönb.-Tem. in Schönbeck-Temesy & Ehrendorfer 1979: 246) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 775), C. woronowii (V.I.Krecz. in Grossheim 1934: 25) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 776), C. tenuifolia (Boissier 1843: 32) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 773), and C. affinis (Boiss. & A.Huet in Boissier 1856: 110) P. Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 770). This group comprises morphologically similar taxa endemic to Türkiye, except for C. affinis , which also occurs in Armenia ( Fig. 3 ).

The phylogeny of Cynanchica remains incompletely resolved based on the published data to date.Various ecological and biological processes, such as hybridization, have contributed to a complex mosaic of different lineages. However, reconstructing the phylogeny of Cynanchica is beyond the scope of this study. Therefore, our dataset employed a wide sampling from Cynanchica mainly from the East Mediterranean area and cpDNA regions, which were also used in previous studies to reveal the phylogenetic relationships of C. paphlagonica . The only nuclear DNA marker that was available for Cynanchica was ITS, which presented challenges due to a high number of ambiguous sites, difficulties in alignment, and ultimately resulted to insufficient phylogenetic signal. Consequently, ITS was not selected for our analyses. Additional chloroplast and nuclear regions are clearly needed to clarify the relationships within the clade to which C. paphlagonica belongs. Overall, addressing species delimitations and relationships within Cynanchica will require an integrative taxonomic approach, incorporating both morphometric and phylogenetic/phylogenomic data.

Morphological comparison: —The taxonomic relationships of Cynanchica paphlagonica ,based on morphological features, are largely congruent with the findings of phylogenetic analysis. It belongs to a small species group, including C. stricta , C. tenuifolia , and C. tenella (Heuff. ex Degen 1897: 196) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 776), characterized by acuminate to mucronate leaves with hyaline mucros up to 0.4 mm long, a large corolla up to 10 mm long with a tube 3–4 times longer than lobes, and flowering stems exceeding 10 cm. Cynanchica tenella , widely distributed in SE Europe and N Türkiye, is the only morphologically similar species that grows sympatrically with C. paphlagonica .

Cynanchica paphlagonica appears most closely related to C. stricta (Boiss.) P.Caputo & Del Guacchio , a polymorphic species distributed across Anatolia, Syria, and Lebanon ( Ehrendorfer & Schönbeck-Temesy 1982) ( Fig. 3 ). Cynanchica stricta comprises five subspecies primarily distinguished by variations in habit, inflorescence structure, leaf morphology, bracts, and corolla characters. Cynanchica paphlagonica is readily distinguished from C. stricta by its more delicate, densely caespitose habit, inflorescence with fewer verticillasters, pale yellow corolla with recurved lobes, and smaller mericarps ( Table 1). These morphological distinctions support species-level differentiation of C. paphlagonica rather than its placement as a subspecies within the C. stricta complex. It appears more closely related to the montane C. stricta subsp. grandiflora and C. stricta subsp. monticola (Ehrenorfer in Schönbeck-Temesy & Ehrendorfer 1979: 246) P.Caputo & Del Guacchio in Del Guacchio & Caputo (2020: 775), particularly the former. Cynanchica stricta subsp. grandiflora , endemic to the Taurus and Anti-Taurus Mountains of SE Anatolia, differs from C. paphlagonica by its more robust, laxly caespitose habit, usually pink corolla with patent lobes, and larger leaves and mericarps. Cynanchica stricta subsp. monticola is further distinguished from C. paphlagonica by its shorter, usually infundibular corolla and scabrid to shortly hispid leaves ( Ehrendorfer & Schönbeck-Temesy 1982).

A detailed morphological comparison between Cynanchica paphlagonica and its closest relatives is presented in Table 1. Cynanchica affinis is a high-altitude species confined to the mountains of NE Anatolia and Armenia ( Fig. 3 ). It differs from C. paphlagonica mainly in corolla colour and morphology, as well as its more compact habit ( Table 1). Cynanchica tenuifolia and C. woronowii are clearly distinguished from C. paphlagonica by their habit, and differences in stem, leaves, and corolla characters ( Table 1). Cynanchica tenella , the only morphologically similar species not included in the phylogenetic analysis, is clearly distinguished from C. paphlagonica mainly by its greyish-green habit, lanceolate to oblong basal leaves, thyrsoid to corymbiform, much-branched and many-flowered inflorescences, and pale pink to white, verrucose corolla (4–6 mm long) with spreading lobes ( Table 1). As no DNA sequences are available for C. tenella , its phylogenetic position within the genus remains entirely unknown. Although C. nitida subsp. nitida also clusters with C. paphlagonica in the phylogenetic tree, it is a low, pulvinate species adapted to high altitudes, morphologically and ecologically distinct from C. paphlagonica , and therefore not included in Table 1.

Preliminary threat assessment: —The new species is currently known only from its type locality. Over the past six years, our team has conducted intensive floristic surveys in the PInarbaŞI area, but so far no additional populations have been found. However, as the species’ habitat (calcareous rocky slopes) is widespread in the region, the possibility of undiscovered populations cannot be excluded. The single known population consists of ca. 80 individuals, occupying an area of about 2 ha (AOO = EOO = 4 km 2). No immediate threats to the population have been observed. Therefore, based on IUCN criterion D ( IUCN Standards and Petitions Subcommittee 2024), we tentatively classify C. paphlagonica as Endangered (EN).

Figures

FIGURE 1. Cynanchica paphlagonica—A: habitat; B: flowering individual; C: inflorescences; D: flowers; E: individual at early flowering stage; F: leaves.

FIGURE 2. The holotype of Cynanchica paphlagonica.

FIGURE 3. Geographical distribution of C. paphlagonica and related species. For C. tenella, only records from Türkiye are included.

FIGURE 4. Phylogram of selected Cynanchica species, mainly from the Eastern Mediterranean and neighboring regions, including the newly described C. paphlagonica (in red), with other genera of Rubieae as outgroups. The tree was inferred from Bayesian analysis of cpDNA sequences. Posterior probabilities (pp)> 0.7 and bootstrap values (bs)> 50% estimated from MrBayes and RAxML analyses are indicated above and below the branches, respectively.