Crocus thracicus Yüzb. & Aslan, 2015

Yüzbaşioğlu, Sirri, Aslan, Serdar & Özhatay, Neriman, 2015, Crocus thracicus (Iridaceae), a new species from north-western Turkey, Phytotaxa 197 (3), pp. 207-214 : 208-213

Crocus thracicus Yüzb. & Aslan sp. nov. ( Figs. 1 , 2).

Crocus thracicus is closely related to C. alexandri . It mainly differs from the latter species because it has the abaxial surface of the outer tepals speckled violet–blue or white and has no white margin (not densely stained violet-blue except a narrow white margin), tepals 17–24 mm (not 20–35 mm), anthers yellow with blackish basal lobes (not wholly yellow).

Type:— TURKEY. A1(E) Kırklareli: Vize, Saray-Vize yolu, c. 10 km, Quercus sp. & Paliurus spina -christi Mill. açıklıkları, 170 m, 8 February 2014, S. Yüzbaşıoğlu 3920, S. Aslan, İ. Sözen, F. Canız (holotype ISTE 102922!, isotype DUOF 5630!).

Corm subglobose-ovoid, 10–12 mm in diameter; tunics coriaceous, splitting longitudinally, with well developed rings at base, rings irregularly toothed. Cataphylls 4–5, silvery white. Leaves usually shorter than or reaching the flowers at the start of anthesis, 3–4(–5), 0.75–1.3 mm wide, dark green, glabrous or minutely ciliate, width of white stripe approximately 1/3 of leaf diameter, no ribs underneath. Throat white, glabrous. Perigone tube white, rarely speckled violet near the apex. Outer segments 17–24 mm long, 6–9 mm wide. Inner segments 14.6–23 mm long, 5.7–8.7 mm wide. All segments white without markings in the adaxial surface. The abaxial surface of outer segments is speckled violet-blue or white, while that of inner segments white or speckled violet-blue at the base. Prophyll absent. Bract and bracteole subequal, conspicuous, bracteol narrower than bract, white. Filaments 3.7–6.4 mm, light yellow, glabrous. Anthers arrow-shaped, 7.3–11.8 mm long, yellow with blackish basal lobes, lobes 1.5–2.5 mm. Connective colourless to light yellow; pollen yellow. Style reddish-orange, divided into 3 branches; apically expanded branches 4–9 mm long. Styles equal to shorter than the stamens, sometimes longer. Capsule ellipsoid, c. 14 mm long; seeds globose, c. 2.5 mm diameter, with prominent caruncle and raphe, pale brown. Chromosome number 2n = 8.

Phenology:—In the wild, the plants flower from February to March.

Proposed conservation status:—This species is known from four populations, and the extent of occurrence is less than 2400 km 2 ( Fig. 3 ). According to preliminary estimation, area of occupancy is less than 12 km 2 and not more than 200 mature individuals are growing in the type locality. All distribution area in Thrace is surrounded by farmland. The destruction of habitat through human encroachment, e.g. land clearing, urbanization, overgrazing, field and road constructions, is the principal threat in the study area. Therefore, it is suggested that this new species should be placed in IUCN threat category Endangered (EN), [B1ab (i, ii, iii, v) + 2ab (i, ii, iii, v)] ( IUCN, 2001).

Karyology:—The chromosome number is counted for this new species 2n = 8 (from type locality). The karyotype formula can be expressed as: 2n = 2x = 8 = 8sm ( Fig. 4 ). The largest chromosome pair is submetacentric (sm), followed by three submetacentric (sm) chromosome pairs. The longest per shortest chromosome ratio (L/S) ranges from 1.65 to 1.95. Intrachromosomal asymmetry (M CA) is 36.04 and interchromosomal asymmetry index (CV CL) is 23.18.

Additional specimens examined (paratypes):— TURKEY. A1(E) Kırklareli: Pınarhisar–Kaynarca yolu, açık alan, kayalık arazi, 250 m, 8 February 2014, S. Yüzbaþýoðlu 3922, Ý. Sözen, F. Canýz (ISTE 102923!, DUOF 5643!). Kırklareli: Vize, Çövenli köyü, meşe açıklıkları, 190 m, 21 February 2014, S. Yüzbaşıoğlu 3949, F. Canız (ISTE 102924!) ; Edirne: Keşan, Keşan–Enez yolu, 7. km, 40 m, 21 February 2014, S. Yüzbaşıoğlu 3946, F. Canız (ISTE 102925!) .

Taxonomic relationships:—According to the classification of Mathew (1982), the new species falls into series Biflori Mathew (1982: 76) . In this classification, C. biflorus was divided into several subspecies distributed from Italy to the Caucasus and Iran. Although C. weldenii Hoppe & Fürnrohr (1840: 208) and C. alexandri Ničić ex Velen. were firstly published as species, they were later classified as subspecies of C. biflorus by Mathew (1982). However, as a result of recent morphologic and molecular investigations, these two taxa are now treated again at species rank ( Randelović et al. 1990, Zevrnja & Vladovic 2005, Harpke et al. 2013). Our morphological observations indicated that the new species is closely allied to C. alexandri and C. weldenii . C. alexandri grows in mountain scrubs or in pastures and stony places on granite and schist at 700–1500 meters in Bulgaria, Serbia and Greece. In Greece, the most common habitat for this species was recorded as clearings in Fagus L. and Pinus L. forests and the subalpine grasslands, where it flowers near melting snow patches ( Karamplianis et al. 2013). C. weldenii is found in North-Eastern Italy, Western Yugoslavia, Northern Albania and Croatia in dry grasslands, open stony places and in sparce pine and oak woods, it generally grows at lower altitudes, between 100 and 750 m ( Mathew 1982). The latter species differs from C. alexandri and C. thracicus in having ribs or ridges on the abaxial leaf surface. The distribution areas of these three taxa do not overlap. Their morphological differences are given in the table ( Table 1).

taxa are taken from literature ( Mathew 1982, Randelović et al. 1990, Rukšāns 2010, Karamplianis et al. 2013).

The chromosome number of C. alexandri , 2n = 8, has been reported by Mathew (1982) and Karamplianis et al. (2013). C. thracicus and C. alexandri share the same diploid number, but their karyotypes are distinct. Indeed C. alexandri has a karyotype formula 2n = 2x = 8 = 6sm + 2 st. Only one count was published for C. weldenii (2n = 8; Brighton et al. 1973), with no information about karyotype structure.

Perhaps another relative of C. thracicus is C. pallidus Kitan. & Drenkovski in Drenkovski & Kitanov (1975: 213), which is known from Bulgaria and Yugoslavia. According to Mathew (1982), this species would be a heterotypic synonym of C. weldenii . However, it was accepted as a distinct species by Randelović et al. (1990) and is clearly differing from C. thracicus , C. alexandri and C. weldenii in having yellow throat in flowers.

FIGURE 2. Habit of Crocus thracicus sp. nov. from type locality (photos: F. Canız).

The new species can be found admixted with C. chrysanthus ( Herbert 1847: 285) Herbert (1843: 83) in many areas ( Fig. 3 ) of European Turkey. However, we found also pure C. thracicus populations, which led us to the idea that we were dealing with a separate species. In the European Turkey, also pure C. chrysanthus populations were observed. As it was stated above, the new species was previously evaluated as an albino form of C. chrysanthus by Mathew (1982). According to the latter author, C. chrysanthus populations in European Turkey would contain many albinos contrarily to Anatolia, where albinism is rarely observed. This identification is based on a specimen in ISTE herbarium (ISTE 23814!). Field research in this location indicated that there are almost equal numbers of individuals of the white form of C. thracicus (Fig. 5a) and C. chrysanthus . In the same locality, a very limited number of speckled individuals (Fig. 5b) and also hybrid individuals between the white form of new species and C. chrysanthus (Fig. 5c) were found.

FIGURE 5. Enez location. (a) white form of C. thracicus , (b) speckled violet–blue form of C. thracicus , (c) hybrid form between white form of C. thracicus and C. chrysanthus (photos: F. Canız).

Figures

FIGURE 1. Crocus thracicus. a: habit. b, d: view of the inner face. c, e: view of outher face. f: leaf cross-section. g: corm tunics.

FIGURE 3. Distribution of Crocus thracicus and C. chrysanthus in Thrace (Turkey).

FIGURE 4. Somatic chromosomes (a), karyotype (b) and idiogram (c) of C. thracicus.