Additional contributions to taxonomy, nomenclature and biogeography of the Turkish Crataegus (Rosaceae) taxa

Abstract Crataegusazarolus L. has a wide distribution pattern from the western Mediterranean coasts to the eastern parts of Iran with several varieties adapted to local climatic conditions. Crataegusazarolusvar.senobaaensisvar. nov. is described as a new variety from southeast Turkey with characteristic deep leaf sinuses, mostly 3–4 pairs of lobes and leaves ovate-oblong in outline. Two varieties of the species are accepted under the name of Crataegusazarolus and the correct names are published here. CrataegusmonogynaJacq.var.odemisiivar. nov. is described from İzmir, in the western part of Turkey. This new variety is distinguished by its orange fruit colour. An outstanding disjunct distribution pattern has been discovered for the recently described species, Crataegusyaltirikii Dönmez. Updated descriptions and infraspecific identification keys for Crataegusazarolus and Crataegusmonogyna are given and pictures and distribution data for the new taxa are also supplied.


Introduction
The genus Crataegus L. grows mostly in the northern hemisphere and prefers forest openings and open areas of steppe. The number of species in the genus is ca. 240 with around 170 species in the New World and 70 species in the Old World (Pojarkova 1939;Meikle 1966;Riedl 1969;Browicz 1972;Christensen 1992;Khatamsaz 1991;Gu and Spongberg 2003;Phipps et al. 2003;Dönmez 2013;Phipps 2018). Phylogenetic studies, based on DNA sequences from both chloroplast and nuclear markers by Campbell et al. (2007), Lo et al. (2007), Potter et al. (2007) and Li et al. (2012), clarified the intergeneric relationships amongst the genera of the tribe Maleae. Subsequent to the publication of a revision of the Old World Crataegus taxa by Christensen (1992), extensive field work, both in Turkey and neighbouring countries by Dönmez (2008), showed that the section Crataegus is extensively diversified, especially in Turkey (Dönmez 2004(Dönmez , 2005(Dönmez , 2007(Dönmez , 2013; Dönmez and Oybak Dönmez 2005). Although exhaustive field work and collections in the region have been undertaken, it is still possible to detect new populations, probably representing new taxa (e.g. Dönmez 2005;Shahbaz and Sadeq 2006;Dönmez 2007Dönmez , 2013Sharifnia et al. 2011).
Ongoing studies both in the field and herbarium resulted in the discovery of a new variety ( Figure 1) and an outstanding distribution pattern of a recently described species C. yaltirikii Dönmez. Moreover, during plant collection for the study on the photochemistry of the Aegean Crataegus species (Özderin et al. 2016), an unusual population of C. monogyna Jacq. with distinct pure yellow fruits has been discovered by the second author ( Figure 2). Further, studies on the populations in the following years by the authors revealed that the fruit character is related to genetic factors and not temporary environmental conditions. Consequently, both specimens are described here as new varieties.
Crataegus azarolus L. is an economically important fruit plant and its fruits have been used for food, jam and other traditional cuisines in the area. Although there is an extensive distribution from Spain to Iran, this species does extensively diversify in Turkey. Two varieties have been described by Browicz (1972) and they have been reduced to synonym by Christensen (1992). Based on the observations of the taxa in the field, it was found that both of them should be accepted as distinct taxa.

Materials and methods
The descriptions of Crataegus azarolus L. var. senobaaensis Dönmez and Crataegus monogyna var. odemisii Dönmez & Özderin are based on field collections of the new taxa at Şırnak, Bitlis and İzmir, observation on the habitat and examination of ca. 600 herbarium specimens from E, EGE, G, HUB, ISTO, K, LE and W (acronyms follow Index Herbariorum; http://sweetgum.nybg.org/science/ih/) by the authors. The preliminary conservation status of the new taxa was assessed using the IUCN (2017) criteria, according to field observations in the type localities and their environs.

Results
The descriptions of the species have been updated according to the relevant literature, field observations and collections, both from the mentioned herbaria and our own collections. The measurements are based on the herbarium materials.

Crataegus azarolus
Ecology and habitat. Crataegus azarolus var. senobaaensis grows in dry steppes from 1250 to 1735 m elevation.
Etymology. The epithet denotes the type locality Şenoba. Preliminary conservation status. Crataegus azarolus var. senobaaensis should be labelled as "Critically Endangered", (CR B1+D) according to the IUCN (2017) threat categories. The area of occupancy is estimated to be smaller than 100 km 2 and the number of examined mature individuals is less than 50. Besides this, all of the examined specimens are known from habitats which are not under threat.
Infraspecific key Turkish taxa of C. azarolus  (Figure 3). Crataegus yaltirikii is a species native to Turkey where it is known from two locations namely Şırnak and Mersin which are far from each other, nearly 400 km distant.
Ecology and habitat. Crataegus yaltirikii grows in Quercus brantii Lindley forest openings at the type locality and amongst the maquis vegetation in Mersin, a recently discovered location.
Conservation status. "LC" threat category was assessed for Crataegus yaltirikii in the description of the species (2005). Based on the new distribution pattern of the species, the threat category of the species was re-evaluated and "LC" is still the appropriate category for the species.

Crataegus monogyna
Habitat. in openings of Pinus nigra forest. Distribution. (Figure 3). Crataegus monogyna var. odemisii is endemic to İzmir; it has a narrow distribution at Gölcük.
Ecology and habitat. Crataegus monogyna var. odemisii grows in openings of Pinus nigra forest between 1050 and 1120 m elevation. The basic vegetation type is maquis at lower elevations of the area. Besides this, Pinus nigra forest replaces it at higher altitudes and steppe vegetation dominates above the tree zone.
Etymology. The epithet of this new variety denotes the collection area, Ödemiş. Preliminary conservation status. Crataegus monogyna var. odemisii should be assigned to "Critically Endangered", (CR B2ab(i,ii,iii,iv), D) according to the IUCN (2017) threat categories. The area of occupancy is estimated to be less than 10 km 2 and the examined specimens are known only from alongside the road. The location is close to the picnic area of the Gölcük Lake and is under threat from fire, cutting and other anthropogenic effects.
Discussion. Two new varieties have been published by Browicz (1972) from Turkey under the species name of C. aronia L. These two varieties were reduced to synonym by Christensen (1992) with their published name and he accepted the name Crataegus azarolus instead of C. aronia. Taxonomic decisions of Christensen have been based solely on herbarium material. During the taxonomic revision of the genus Crataegus, the first author had the opportunity to observe these varieties in their habitats alongside the complete set of morphological variations of the species. Moreover, morphological studies on the large set of herbarium material in the above-mentioned herbaria and fieldwork from Greece to Iran provided more opportunity to observe all kinds of variation of C. azarolus and the closely related taxa. Consequently, based on field observations and herbarium studies on the collected materials, these two varieties, namely Crataegus azarolus L. var. dentata (Browicz) Dönmez and Crataegus azarolus L. var. minuta (Browicz) Dönmez should be accepted as distinct taxa and they should be given as new combinations under the species name of Crataegus azarolus.
Crataegus monogyna is one of the most polymorphic species amongst the Eurasian Crataegus taxa with respect to leaf morphology and indumentum. Due to local variations of the species and species concepts by the authors who studied Crataegus, many new taxa have been described. In addition, new combinations and alteration of their status have been made. Based on these taxonomic and nomenclatural novelties, both taxonomic and nomenclatural synonyms of about 200 names have been listed by Christensen (1992). In C. monogyna, extensive variations in leaf morphology and indumentum are present, whereas variations in fruit colour are limited. Fruit colour of C. monogyna is clearly red and/or with degrees of red. Specimens of the new variety, C. monogyna var. odemisii are yellow. Red and various degrees of red colour for fruit of infraspecific C. monogyna taxa have been observed by the second author and they have hundreds of representative specimens for these fruit colours in the above-mentioned herbaria. According to observations on the fruit colour of single pyrened Crataegus taxon, it is a constant character and unique in the infraspecific taxa of C. monogyna. Hence, it is worthwhile accepting this population as a separate taxonomic status, as a variety.
Crataegus yaltirikii Dönmez is a recently described new species from southeast Turkey and we found a new population of the species on the Taurus Mountain ranges, nearly 400 km away from the type locality. Climatic conditions of these two localities are different; the type locality is a cold and snowy area, whereas the recently discovered locality is characterised by hot and dry summers, rainy and warm winters. We have not yet obtained molecular works on these disjunct populations. Besides this, we assume that these populations should be local ecotypes of the species.
Infraspecific key to Turkish taxa of Crataegus monogyna