FIRST RECORD OF THE GENUS XEROPICTA MONTEROSATO, 1892 (GASTROPODA: EUPULMONATA: GEOMITRIDAE) IN SERBIA

a Bstract : Xeropicta Monterosato is a pulmonate xerophilous snail genus of the family Geomitridae. It is distributed in the eastern Mediterranean and the Black Sea region and also in Asia Minor, Ukraine, the Caucasus, the Middle East and Iran. No species of this genus was known from Serbia until now. Here, we present the first record of Xeropicta from Serbia. Morphological, anatomical and ecological characteristics of the species as well as its variation are discussed. Because of the wide shell variation, the analysed specimens were identified based on anatomy, and correspond to X. krynickii . However, in their shell morphology, some specimens resemble X. derbentina . Therefore, here they are treated as X. cf. krynickii . Further studies should shed more light on their identity.


INTRODUCTION
A large body of data on land snails of Serbia was collected by Petar S. Pavlović, most intensively in the period from 1905to 1912(PaVloVić 1912, ToMić 1959. His material is now in the Natural History Museum in Belgrade. Later, the land snails and slugs of Serbia were studied by Božana Karaman at the end of the 20th and the beginning of the 21st century. She published numerous faunistic papers and summarised most of her data in the checklist of gastropods of Serbia (karaman 2007). In that list, she reported a total of 184 species of land snails and slugs. As many species names have changed in the meantime, as well the species number in general, the list requires significant changes. Moreover, there are some species in that list that occur in adjacent countries but their presence in Serbia is doubtful. There is a possibility that some of the records are actually from Montenegro. This can be explained by the fact that Serbia and Montenegro were one country until 2006; the checklist was published in 2007 and these species were probably in-cluded accidentally. However, the list of species and the commentary on the general diversity of Serbian gastropods is beyond the scope of this paper.
Xeropicta Monterosato, 1892 is a pulmonate xerophilous snail genus of the family Geomitridae (molluscaBase 2021). It is distributed in the eastern Mediterranean and the Black Sea region, as well as in Asia Minor, Ukraine, the Caucasus, the Middle East and Iran (De mattia 2007). Four species of Xeropicta inhabit Europe, namely: X. akrotirica Gittenberger, 1991, X. derbentina (Krynicki, 1836), X. krynickii (Krynicki, 1833) and X. ledereri (L. Pfeiffer, 1856. Of these four species, two -X. akrotirica and X. ledereri -are known only from Cyprus, while the other two are more widely distributed (welterschultes 2012). Xeropicta krynickii is distributed in the eastern part of the Mediterranean region and reaching the Caspian Sea, but is also present in its western parts, for example in Montenegro, which is also the westernmost known fragment of its distri-https://doi.org/10.12657/folmal.030.008

MATERIAL AND METHODS
In Vrčin settlement, Grocka municipality in Belgrade (coordinates: 44°40'35.50"N, 20°36'28.88"E; altitude: 149 m a.s.l.) ( Fig. 1), around 40 specimens of X. krynickii were collected on 15.05.2021 in a house yard. All snails were collected by hand and preserved in 70% ethanol. Their shells and genitalia were photographed and basic shell characters were measured (shell and aperture height and width, umbilicus width) using stereomicroscope Nikon SMZ800N equipped with a Nikon DS-Fi2 camera. A Nikon DS-L3 control unit was used to set scale bars. Snails were identified conchologically and anatomically following schileyko (2006)  General description of the species. Shell consisting of 4-5.5 whorls. Colouration white with brown-ish bands and spots, or uniformly white. Shell surface finely striated. Body whorl slightly descending near the aperture. Umbilicus narrow and slightly eccentric, with 0.5 previous whorl visible through it (although some of our specimens anatomically resembling X. krynickii do not show the described appearance of umbilicus (Fig. 2)). Body pale yellowish, mantle creamy (welter-schultes 2012, Gural- . Penis with long flagellum, 2 or 3 times shorter than epiphallus (Fig. 3). Inside penis, a strongly developed penial papilla with an outer sheath (Figs 4-7). Vagina with 10-14 digitiform accessory glands and dart-sac complex consisting of four stylophores entering vagina independently (Fig. 3). Darts present in proximal stylophores and absent in distal ones. Penial appendage strongly developed. A crest-like structure can be found inside penial appendage gradually increasing in height until reaching the atrial aperture (De MaTTia & Pešić 2014) (Figs 3-4).
Comparison with similar species. The species can be easily confused with X. derbentina and dissection is needed to separate them clearly. Xeropicta derbentina also has a dart-sac complex consisting of four stylophores but it has a short flagellum, much shorter than the epiphallus (De MaTTia & Pešić 2014). The other two geomitrids which occur in Serbia and can be confused with X. krynickii are Xerolenta obvia (Menke, 1828) and Cernuella virgata (Da Costa, 1778). However, both X. obvia and C. virgata have two dart sacs and not four like X. krynickii (schileyko 2006). Conchologically, X. obvia is usually flatter with wider umbilicus and C. virgata is usually larger and more globular (welter-schultes 2012).

DISCUSSION
The analysed specimens from the population in Belgrade showed relatively small variation in shell dimensions (only 3 mm difference between the largest and the smallest specimen). The umbilicus was 1/6 of shell width in most cases, sometimes 1/5. However, significant variation was observed regarding shell colouration (Fig. 2). Some specimens were uniformly white with a light band, sometimes faintly visible, in the middle of the periphery. Other specimens were more intensively coloured, with variable number of more or less pronounced brownish bands, sometimes broken into numerous brownish freckles, giving the shell a much darker appearance. In some specimens, the shell was almost entirely white with faint brownish bands only on the body whorl. No significant anatomical variation was observed. In all the specimens dissected (n = 5), the flagellum was approximately 2.5 times shorter than the epiphallus. These snails are known to vary greatly in their shell appearance, and proper identification often requires dissection and observation of anatomical traits, as stated by De MaTTia & Pešić (2014) who also found a population of X. krynickii resembling X. obvia in its external appearance. Our population included several specimens externally resembling X. derbentina, but all of those matched X. krynickii anatomically. Because of these "shared" characters, none of our specimens could be identified to the species level with absolute certainty. Finding and analysing more populations could resolve the confusion and even confirm the presence of both species in Serbia.
Xeropicta is adapted to many xerothermic habitats and is easily dispersed by humans (Gural-sVerloVa & Gural 2017). Xeropicta krynickii, as well as X. derbentina, expanded its distribution range significantly due to human activities. One of the examples is road and railway transport (Gural-sVerloVa & GleBa 2015). It is almost certain that the presence  (anDerson 2000, meerBurG et al. 2009, kuchBoeV et al. 2012, GérarD et al. 2020. According to anDerson (2000), snails of the genera Cernuella, Cochlicella, Helicella, Xerolenta and Xeropicta are intermediate hosts of lung nematode parasites of several artiodactyls. A study from Uzbekistan (kuchBoeV et al. 2012) showed that X. candaharica (L. Pfeiffer, 1846) was the species of land snail most commonly infected by the nematodes of the family Protostrongylidae, lung parasites of Bovidae mostly. These snails also serve as intermediate hosts of some trematodes, for example the genus Brachylaima (GérarD et al. 2020). Apart from rodents, these trematodes can also infect humans and cause brachylaimiasis manifested by abdominal pain and diarrhea with mortality between 5% and 10% when untreated (meerBurG et al.

2009
). Xerophilous snails are mostly second intermediate hosts of these trematodes but, for example, X. krynickii is the first intermediate host of Brachylaima mesostoma (Rudolphi, 1803) though it can also be the second along with several other species (GérarD et al. 2020). As pests, a study from Serbia has shown that C. virgata caused enough damage to green onion in vegetable plots to make it unfit to be eaten or sold, and there are numerous other examples all over the world (STojnić et al. 2013). Xerolenta obvia is reported from Andorra as invasive species, and is known as an intermediate host of many parasites, as well as an agricultural pest (martínez-ortí & BorreDà 2022). In the USA, there are several reports of Theba pisana (O. F. Müller, 1774) (Helicidae) as an agricultural pest (VenDetti et al. 2021).
The importance of these snails as intermediate hosts of various parasites and as agricultural pests further emphasises the importance of their correct identification and of documenting their spread or decline (De mattia & Páll-GerGely 2014). It is important to note that this species has not caused any damage till now, but its spread, as well as possible methods of its control if necessary, will be further studied.