Contributions to the Hypericum L. section Oligostema (Boiss.) Stef. (Hypericaceae), and Hypericum turcicum sp. nov. as a new species from Turkey

Hypericum turcicum (Hypericaceae) is described and illustrated as a new species from Beypazarı in Ankara Province in Northwest Anatolia, Turkey. The new species belongs to the section Oligostema, and it is closely related to H. aucheri. Diagnostic characters, description, detailed illustrations, ecology, and pollen and seed morphology are presented in this study. In addition, this study evaluates H. kazdaghense, which was previously accepted as a synonym of H. aucheri, as a distinct species and discusses the similarities and differences between H. turcicum and H. aucheri.

photographs were taken with a Leica ICC50 HD light microscope. Measurements were taken from at least 30 pollen grains for each morphological characteristic. For scanning electron microscopy (SEM), dry pollen grains were transferred onto stubs, coated with gold, and then investigated and photographed with a JEOL JSM 6060 SEM. The pollen terminology of Faegri and Iversen (1992) and Punt et al. (2007) was followed. The class of pollen shape, based partly on the P/E ratio, was identified following Erdtman (1969). The seed terminology was adopted from Barthlott (1981) and Bojnansky and Fargasova (2007).

Pollen morphology
The pollen grains of Hypericum turcicum are radially symmetrical and isopolar. The pollen grains are prolate  with the polar axes 18.75-21.75 µm and the equatorial axes 14-17 µm. The P/E ratio is 1.33. The outline of the pollen grains is elliptic to obtusely rectangular in equatorial view and circular in polar view. The aperture type is trizonocolporate. Colpus is long, its length is 14-19 µm and width 3-5 µm. Colpus membrane is more or less granulate. The porus is 6-8 µm in length and 5.5-7 µm in width. The shape of porus is lalongate or lolongate. The exine and intine are 0.5-1 µm and 0.5-0.75 µm thick, respectively. The exine ornamentation is microreticulate in the polar and equatorial regions. In H. aucheri, the pollen grains are radially symmetrical and isopolar. The pollen grains are subprolate, with the polar axes 17-20 µm and the equatorial axes 14-16 µm. The P/E ratio is 1.17. The outline of the pollen grains is elliptic to obtusely rectangular in equatorial view and circular in polar view. The aperture type is trizonocolporate. Colpus is long, its length is 13-17 µm and width 4-5 µm. Colpus membrane is more or less granulate. The porus is 6-7 µm in length and 5.25-7 µm in width. The shape of porus is lalongate or lolongate. The exine and intine are 0.75-1 µm and 0.5-0.75 µm thick, respectively. The exine ornamentation is microreticulate in the polar and equatorial regions ( Figure 4).

Seed morphology
Seeds of Hypericum turcicum are brown, oblong, not carinate, 0.86-1.08 × 0.4-0.5 mm. Epidermal cells are polygonal with conspicuous and flat anticlinal walls showing a reticulate appearance and conspicuous, flat or concave and also striped periclinal walls. The surface ornamentation is reticulate-striate ( Figure 5).

Etymology
The epithet is derived from the name Turkey.

Distribution and ecology
Hypericum turcicum is endemic to Turkey and grows in Northwestern Anatolia (Beypazarı, Ankara Province) and

Discussion
The sections Oligostema and Crossophyllum are morphologically similar to each other. Robson evaluated the species belonging to the section Crossophyllum in Group F in Flora of Turkey and emphasized some characters such as leaves auriculate and gland fringed or sepals entire and broadly imbricate. The section Oligostema in Group E has fimbriate or long denticulate (teeth ca. 0.5-3 mm), and the sepals and the capsule valves have longitudinal vittae that were distinguished from the other sections (Robson, 1967). In the subsequent years, it was observed that the species belonging to both sections Crossophyllum and Oligostema are very close to each other and generally have 3 stamen fascicles and 3 styles as well as capsule valves with longitudinal vittae as described in Robson's monograph on the genus Hypericum. However, it was observed that the Oligostema section has black anther glands and 3 styles. If there are 5 styles, then the plant is prostrate to ascending with leaves oblanceolate-spathulate to elliptic, as distinguished from section Crossophyllum with amber anther glands or, if black, then there are 5 styles and the plant is erect with linear leaves. Based on Flora of Turkey and according to Robson (2010a), we decided that H. turcicum can be classified into the section Oligostema after taking these features into consideration.
According to Flora of Turkey, Hypericum sect. Oligostema is represented by H. aucheri and H. kazdaghense Y. Gemici & Leblebici (Robson, 1967;Dönmez, 2000). However, Robson revealed that the anther glands in H. aucheri are amber, whereas they are black in the rest of this section. In Oligostema they are black. Therefore, H. aucheri has been transferred to Hypericum sect. Crossophyllum (Robson, 2010a).
In 1995, Hypericum kazdaghense Y.Gemici & Leblebici sect. Oligostema was described as new to science. This new species is morphologically similar to H. aucheri, which grows in the same area, but differs from it by having dimorphic leaves on sterile and fertile shoots, the dichasium inflorescence, anthers without black glands, and reticulate-foveate seeds (Gemici and Leblebici, 1995). However, H. kazdaghense was evaluated as a synonym of H. aucheri (Robson, 2010a). Robson deduced from the photographs of Dirmenci et al. (2007) that the shoots of H. kazdaghense are divergent-ascending rather than prostrate as described, and the dimorphic leaves are the only distinguishing character. Therefore, he stated that it seemed to be no more than a high-altitude form of H. aucheri. Our examination of the H. kazdaghense samples in the photos by Dirmenci et al. (2007) determined that the photos are not of H. kazdaghense, but instead of H. aucheri. Also, we understood that Robson had not seen type specimens of H. kazdaghense. When we examined the type specimens of H. kazdaghense (EGE26768), we observed that these 2 species are different ( Figure 6). Therefore, we decided that H. kazdaghense is not synonymous with H. aucheri.
Hypericum turcicum resembles H. aucheri and H. kazdaghense. However, it can be easily distinguished from both species by several noticeable morphological characters. H. turcicum differs from H. aucheri in having black scattered glands at the stem, elliptic to narrowly elliptic or oblong elliptic leaves, not having laminar glands (on the leaves) or having them scarcely punctiform and smaller than the sepals and petals, and anther glands that are black. H. turcicum differs from H. kazdaghense in having erect or decumbent stems and scattered glands, not having dimorphic leaves, and having monochasium inflorescence. More detailed differences are given in the Table. The habitat of H. turcicum is quite remarkable. This new species was collected from salty floors on gypsum hills, and it has been observed that this new species grows along with some other species specific to this habitat.
The pollen morphology of H. turcicum and the closely related species H. aucheri is rather similar, but the pollen shape is different. The shape of pollen grains is prolate in H. turcicum, while it is subprolate in H. aucheri.   H. aucheri (Robson, 2012) H. kazdaghense (Gemici and Leblebici, 1995)