Linum aksehirense (sect. Dasylinum, Linaceae), a new species from Central Anatolia (Turkey)

Abstract Linum aksehirense (Linaceae) is described as a new species known from the slopes of the Sultan Mountains in the Akşehir district of Konya in Central Anatolia (Turkey). It is most similar to L. pubescens Banks & Sol. and L. anisocalyx P.H.Davis, from which it is easily distinguished by its stem leaf shape, sepal shape and petal colour. Seed and pollen surface ornamentations were photographed under SEM microscopy to explore micromorphological characters distinguishing the new species from close relatives. In addition, photographs of living material, a distribution map, ecological details, and an identification key are provided.


Introduction
The genus Linum Linnaeus (Linaceae) is comprised of about 200 species in the Linaceae family. Linum is distributed mainly in North America, the Balkan Peninsula, Anatolia, as well as in Eurasia and Africa (Robertson 1971), but it is also represented in South America and Australasia.
Linum was first described by Linnaeus (1753). The f irst comprehensive study on the genus was made by Planchon (1847Planchon ( , 1848. The most recent worldwide treatment of Linum was done by Winkler (1931). According to Winkler (1931) and Planchon (1847Planchon ( , 1848, Linum is divided into five sections. The genus has been the subject of several taxonomic studies and regional revisions, such as those focusing on American and South African Linum species (Rogers 1963(Rogers , 1981Mildner and Rogers 1978), as well as Flora Europaea (Ockendon and Walters 1968), Flora of the U.S.S.R. (Yuzepchuk 1974), and Flora of Turkey and the Aegean Islands (Davis 1967). The genus plays an important role in the economic and social development of humans. For example, the seeds of L. usitatissimum are used nutritionally and medicinally. Linseed oil is also a significant source of inks, varnishes, and lubricants (McDill et al. 2009).
Linum sect. Dasylinum is characterised by having perennial or annual life cycles and distinct morphological characteristics. Leaves are alternate, often hairy. Petals usually have coherent claws and are blue, pink or white. Capsules are hairy or glabrous (Davis 1967). There have been numerous studies on the morphology of Linum in Turkey by several authors (Davis 1967;Kaynak 2008, 2010;Yılmaz 2010). There have also been investigations on a worldwide scale concerning the palynology (Erdtman 1969; Rogers and Xavier 1971;Saad 1961Saad , 1962Xavier et al. 1980;Rogers 1985;Talebi et al. 2012), karyology (Ray 1944;Harris 1968;Rogers et al. 1972) and anatomy (Winkler 1931;Metcalfe and Chalk 1950) of the genus. There has been just one study on Linum seeds, which covers several species of the genus (Özcan and Zorlu 2009).
From a biogeographical and evolutionary point of view, McDill et al. (2009) reported that section Linum and Dasylinum were not monophyletic and that Linum appears to have arisen in Eurasia, from which it spread to Africa, North America, South America and Australasia.
We collected samples of what we suspected could be a new species of Linum while conducting field work around the Sultan Mountains between 2011 and 2017. The specimens were checked against the Flora of Turkey and the East Aegean Islands, as well as neighbouring floras (Flora Iranica, Flora Iraq, Flora of the U.S.S.R. and Flora Europaea). We subsequently decided that it was a species new to science.
The aim of this study was to describe the new species, named Linum aksehirense, occurring in the Sultan Mountains (Akşehir, Konya), in terms of its morphology, palynology and seed micromorphology.

Material and methods
Field collections were carried out in the Sultan Mountains from 2011 to 2017. Collected specimens were dried using traditional procedures and were deposited in the KNYA Herbarium. They were identified using the Flora of Turkey and the East Aegean Islands using stereo microscopy and checking them against other Linum accounts found in relevant literature. The taxonomical description of the species was made according to Davis (1967).

Linum aksehirense
Paratypes Phenology. The new species was observed flowering in July and collected fruiting from July to August.
Etymology. The species epithet comes from 'Akşehir', where the new species is found. Proposed Turkish name for the new species. Akşehir keteni. Distribution and conservation status. Linum aksehirense is known from three localities in Konya province, in the Irano-Turanian phytogeographic region (Fig. 1). Its area of occupancy is estimated to be less than 500 km 2 . The number of mature individual plants is estimated to be less than 250. Being an annual gives this new species a crucial advantage for survival against potential threats, which include the destruction of brush by locals, road construction and deterioration of habitat. Thus, according to criterion B and D, it can be included in the EN (Endangered) category (IUCN 2001;2016).

Discussion
Linum aksehirense is similar to L. pubescens, L. anisocalyx and L. viscosum in morphology. However, it differs from these similar species in several vegetative and reproductive characters (Table 1). According to Davis (1967), L. anisocalyx is closely related to L. pubescens, differing from L. pubescens primarily by its strongly dimorphic sepals (not dimorphic), which are rhomboid-lanceolate and glandular-margined.
Linum aksehirense can be distinguished from L. viscosum, by its spathulate not evanescent (vs. lanceolate, ovate-lanceolate, evanescent), sepal size of 12-14 × 2-3 mm (vs. 6-9 × 1-1.5 mm), petal colour, which is blue-violet with a yellowish limb base (vs. pink), and in its petal size, which is 27-33 mm (vs. 18-21 mm). Xavier et al. (1980) described the basic pollen grain in Linum as subspheroidal, about 50 µm in diameter, isopolar, radially symmetric, tricolpate, colpi with pointed ends. However, in our study L. aksehirense had subprolate pollen shape. According to Talebi et al. (2012)'s palynologic study on four section of the Linaceae, including 15 taxa of Linum, in all examined taxa the pollen shape in polar view was circular (except in L. densifolorum where it was concave-triangular) and also the exine sculpturing pattern showed a clavate, pilate and gemmate to baculate form. Talebi et al. (2012) reported that pollen features of L. densifolorum consisted of an oblate-spheroidal pollen shape and small and large gemmate exine ornamentation. Our findings showed that L. aksehirense had subprolate pollen shape and the exine ornamentation was densely gemmate (Fig. 5 A-C). In terms of pollen micromorphology, palynological results demonstrated that there are no clear differences among species of the same section. However, pollen shape can be used to distinguish species. Özcan and Zorlu (2009) studied seed surface patterns Linum genus and found reticulate-ruminate patterns in sect. Dasylinum. Özcan and Zorlu (2009) showed that seed patterns provide characters to distinguish taxa at specific and infraspecific levels.
In this study, the micromorphological study of the seeds showed that there were clear differences among the studied species. According to our findings, Linum aksehirense had reticulate-rugulose-ruminate sculpturing while L. pubescens exhibited reticulaterugulose-granulate and L. anisocalyx showed reticulate-rugulose ( Fig. 6 A-C).

Conclusion
With the discovery of this new species, the number of species of Linum in Turkey has risen to 55. This study provides material and data to aid further research on this significant genus of the Linaceae.