Distribution and life-history traits of Calathus cinctus Motschulsky, 1850 (Coleoptera: Carabidae) in Croatia, with distribution of closely related species

Abstract

Calathus cinctus Motschulsky, 1850 was only recently separated from the group Calathus melanocephalus (Linnaeus, 1758). C. cinctus has now been recorded for the first time in Croatia, along the temporary Krčić River situated beneath Mt. Dinara. However, revision of museum collections revealed that this species also occurs at other localities in Croatia, in the Alpine region and along the Adriatic coast. Its sister species C. melanocephalus, as the type species of the group, is widely distributed in Croatia, whereas C. mollis Marsham, 1802 is mostly restricted to the coastal region, with a few records from Alpine and Continental Croatia. The distribution range of C. cinctus overlaps with the distribution ranges of its sister species. Life-history traits were studied using pitfall traps in a karst region of Croatia, including eu-Mediterranean and sub-Mediterranean zones, in riparian and karst habitats, and on agricultural land. Based on goodness-of-fit criteria, the zero-inflated negative binomial model and negative binomial model best described the distribution of C. cinctus. For both models, there was a statistically significant difference between habitat types for activity density, indicating that C. cinctus has a preference for open habitats. It was recorded above a range of soil types (e.g. red, brown, sandy, cultivated), with sparse vegetation, suggesting that sufficient sun exposure is a more important requirement than soil type. The seasonal dynamics of C. cinctus differed between eu-Mediterranean and sub-Mediterranean zones, despite the rather close proximity of the studied localities. Geographical variability of seasonal activity was most likely due to differences in climate, altitude and the vicinity of the high mountain. Calathus cinctus populations in both zones were wing-dimorphic, with brachypterous specimens prevailing in both populations, indicating population stability.

Keywords:

• Calathus mollis
• Calathus melanocephalus
• first record
• seasonal dynamics
• seasonal activity

Introduction

Calathus cinctus (synonyms: Calathus ruficollis Gautier des Cottes, 1868 and Calathus erythroderus Gemminger & Harold, 1868) belongs to the genus Calathus Bonelli, 1810 and subgenus Neocalathus Ball & Nègre, 1972 (Löbl & Smetana 2003). The genus has mainly a Holarctic distribution, and is species rich including several endemic species (Ruiz et al. 2010). Calathus cinctus was recently separated from the C. melanocephalus (Linnaeus, 1758) group that was comprised of three species: C. cinctus, C. mollis Marsham, 1802 and C. melanocephalus, the latter being the type species (Aukema 1990). Previously, C. cinctus was considered a subspecies of C. mollis (Lindroth 1945). The taxonomic status of this group was questioned several times in the past due to the frequent occurrence of morphologically intermediate specimens (see Aukema 1990). However, cross-breeding results showed that these species are reproductively isolated (Aukema 1990).

All three species are distributed in the Palaearctic region, having a mainly European distribution (Löbl & Smetana 2003). Calathus melanocephalus has the widest distribution range of all three species and occurs not only in Europe, but also in North Africa and Southwest Asia (up to the Caucasus and east to Trans-Baikal in Siberia) (Aukema 1990; Löbl & Smetana 2003). According to the present knowledge, C. mollis has a wider distribution range than previously documented (Aukema 1990; Löbl & Smetana 2003). Although it occurs in most European countries, it is mainly confined to coastal areas of the Atlantic and the Mediterranean (Aukema 1990; Anderson et al. 2000; Löbl & Smetana 2003). It also occurs along the Mediterranean coast of North Africa and the Middle East (Löbl & Smetana 2003). Calathus cinctus has a more restricted distribution range than its two sister species. It has been recorded in several European countries, ranging from Great Britain and Portugal in the west to Latvia and Greece in the east. It appears that C. cinctus does not occur as far north the other two species, but in the Mediterranean area it extends farther south, from Morocco to Syria (Aukema 1990; Löbl & Smetana 2003).

In northern and central Europe, C. cinctus and both its sister species prefer open habitats with sparse vegetation exposed to sun (Thiele 1977; Aukema 1990; Lindroth 1992a). They occur in dry grasslands, heaths, dunes, meadows, pastures, gardens and arable lands (e.g. Thiele 1977; Lindroth 1992a; Anderson et al. 2000; Luff 2002) and often achieve their greatest abundance on sandy or gravel-mixed soil (Lindroth 1992a).

Life-history traits are appropriate indicators of habitat changes (e.g. fragmentation, habitat loss) and as such are useful tools in applied conservation biology (Henle et al. 2004; Barbaro & Van Halder 2009). Calathus cinctus life-history traits, including daily and annual rhythms, reproduction, feeding and dispersal ability, are well known in northern Europe (Aukema 1990), while there are no data from the Mediterranean area. As previously documented for other carabid beetle species, species phenology is often regionally specific (e.g. Dülge 1994; Matalin 2006; Kádár et al. 2015); thus, regional data are required in order to validate generalisations based on life-history traits.

The objectives of this paper are: (1) to present the first finding of C. cinctus and its distribution in Croatia, together with the distribution of its sister species; and (2) to present further data on C. cinctus life-history traits (e.g. habitat preferences, seasonal dynamics, sex ratio, dispersal abilities). Distribution data of the C. melanocephalus group are based on literature data, and museum and private collections. Life-history traits of C. cinctus are documented from wet and karst habitats located in the eu-Mediterranean and sub-Mediterranean zones of Croatia. These regions are geographically close though they differ in terms of climate and vegetation (Zaninović et al. 2008; Vukelić 2012).

Materials and methods

Study area

The study was conducted in the karst region of Croatia, in three different riparian and adjacent habitats: around the Krčić River (44°02ʹ20.2“N; 16°15ʹ53.9”E), around Vrana Lake (43°57ʹ35.4“N; 15°33ʹ34.8”E) and in the Nin saltpan (44°14ʹ34.49“N; 15°11ʹ25.4”E). All localities are situated in the Mediterranean region, Krčić River in the sub-Mediterranean zone of deciduous vegetation and the two others in the eu-Mediterranean zone of evergreen vegetation. The climate around Vrana Lake and the Nin saltpan is a typical Mediterranean climate with hot summers, while the area of Krčić River has a temperate humid climate with hot summers (Šegota & Filipčić 2003).

The Krčić River is situated beneath Mt. Dinara, at an altitude of 370 m. It is a temporary river that typically dries up during the hot summer and early autumn months. The catchment area of the Krčić River covers 157 km², while the length of its surface flow is 10.5 km. It is characterised by both surface and subsurface flow dynamics and ends with a 40-m-high waterfall falling into the Krka River (Bonacci et al. 2006).

Vrana Lake, with an area of 30 km², is the largest coastal lake in Dalmatia, protected as a nature park. The lake is a karst cryptodepression that interacts with the sea and ground waters. The elevation of its surface is only 0.1 m. Although Vrana Lake is separated from the Adriatic Sea by a limestone ridge (800–2500 m wide), it is specifically influenced by the sea since it is directly connected to it by the 800 m long Prosika canal (Katalinić et al. 2008).

The Nin saltpan is located in the shallow lagoon of Nin Bay, covering an area of 0.55 km². This area was previously a salt marsh, though saltpans, or salt evaporation ponds, were created over time for the extraction of salt from seawater. These salt ponds are separated by earthen levees to regulate water levels that vary during the year, depending on the phase of salt production, and are productive resting and feeding grounds for many water bird species.

Sampling and identification

Calathus cinctus was collected using pitfall traps, together with other soil arthropods. Soil fauna was sampled along the course of the Krčić River in two main habitat types: riparian and karst (Table I). Riparian habitats were located parallel to the river course, while karst habitats were located at least 30 m away from riparian habitats. Within each habitat type, 36 sites were selected; each was sampled with three pitfall traps, placed 5 m apart in a linear transect. In total, 216 pitfall traps were set. The traps were partially filled with a 3:2 solution of ethylene glycol and water. To reduce the surface tension of the liquid, a drop of unscented detergent was added. A dark roof was placed above each pitfall trap to protect them from rain and litter. Samples were collected monthly from April to late November in 2014. The collected specimens were kept in 75% ethyl alcohol.

Near Vrana Lake, C. cinctus was sampled by pitfall traps in riparian (reed beds and wet meadows) and karst habitats (Mediterranean shrublands, agricultural lands and Aleppo pine forests; Table I). In each habitat type, three sites were selected, with the exception of reed beds and wet meadows, which were sampled with four sites (in total 17 sites). At each site, five pitfall traps were arranged in a transect line at 5-m intervals. In total, 85 pitfall traps were set. The traps were filled with a solution of wine vinegar, salt and water. A roof was placed above each trap. Soil fauna was sampled monthly from January to December in 2007. The collected specimens were pinned or kept dry.

Table I. Vegetation composition and habitat description of the studied habitats along the Krčić River, Vrana Lake and the Nin saltpan (Croatia).

Location	Habitats	Vegetation	Dominant plant species	Habitat description	Number of sites
Krčić River	Riparian	Class Agrostitetea stoloniferae Oberd. in Oberd. et al. 1967	Agrostis stolonifera L.	Pastures, periodically inundated; used for grazing of sheep; brown shallow soil	36
		Ass. Salicetum purpureae Wendelberger-Zelinka, 1952	Salix purpurea L.	Shrubs, periodically inundated; humid sandy soil
		Order Populetalia albae Br.-Bl. ex Tchou 1948	Populus alba L.	Old flooded forest, periodically inundated; humid sandy soil enriched with humus
	Karst	Alliance Ostryo-Carpinion orientalis Horvat (1954) 1958	Ostrya carpinifolia Scop., Carpinus orientalis Mill., Fraxinus ornus L., Quercus pubescens Willd., Juniperus oxycedrus L.	Thermophiolus shrublands; dry and brown soil – shallowly covering limestone bedrock	36
		Alliance Satureion subspicatae Horvat 1962	Chrysopogon gryllus (L.) Trin., Satureja montana L., Galium lucidum All., Teucrium chamaedrys L.	Pastures; dry and brown soil – shallowly covering limestone bedrock
Vrana Lake	Riparian	Order Trifolio–Hordeetalia Horvatić 1963, around ponds Juncetum maritimo-acuti Horvatić 1934 association	A. stolonifera, Eleocharis palustris (L.) Roem. et Schult., Oenanthe fistulosa L., Mentha aquatica L., Potentilla reptans L.	Meadows, periodically inundated; used for grazing and watering for sheep	4
		Ass. Phragmitetum australe s.l.	Phragmites australis (Cav.) Trin. ex Steud.	Reed beds; humid sandy soil	4
	Karst	Agricultural land	Olea europaea L., Vitis vinifera L.	Olive groves and vineyards; terra rosa soil	3
		Alliance Quercion ilicis Br.-Bl. Ex Molinier 1934	Quercus ilex L., Pistacia lentiscus L., Phyllirea media L., Arbutus unedo L. and Juniperus oxycedrus L.	Mediterranean shrubs; dry and brown soil – shallowly covering limestone bedrock	3
		Pinus halepensis plantation	Pinus halepensis Miller	Aleppo pine forests; dry shallow brown soil	3
Nin Saltpan	Riparian	Ass. Puccinellio fesuciformis-Salicornietum fruticosae (Br.-Bl. 1928) Géhu 1967	Salicornia fruticosa L., Puccinellia festuciformis (Host.) Parl.	Levees, periodically inundated	4
	Sand deposits	Order Scorzonero–Chrysopogonetalia Horvatić et Horvat (1956) 1958	C. gryllu, Bromus errectus Huds., Aira elegantissima Schur	Higher dikes -sub-Mediterranean dry grasslands, never flooded	4
		Ass. Salicornion patulae Géhu 1967 & Géhu-Franck ex Rivas-Martinez 1990	Salicornia europaea L.	Muddy pools	4

In the Nin saltpan, soil fauna was collected using pitfall traps in three habitats: dikes, levees and dry salt pools (Table I). Within each habitat type, four sites were selected, each sampled with five pitfall traps, placed 5 m apart in a transect line. In total, 60 pitfall traps were set. The traps were filled with a solution of wine vinegar, salt and water. Samples were collected monthly from April to August 2011. At this time, sampling was stopped as the saltpan is an important nesting area for the black-winged stilt [Himantopus himantopus (Linnaeus, 1758)] and adults began to feed on the soil invertebrates from the pitfall traps. All collected specimens were pinned or kept dry.

Calathus cinctus was identified using Aukema (1990) and Lompe (2015). Nomenclature follows Löbl and Smetana (2003). Voucher specimens are deposited in the first author’s collection (Department of Biology, Faculty of Science, Zagreb, Croatia) and the Coleopteran collection (National Museum Zadar, Croatia).

Vegetation analysis

Vegetation of the studied habitats was represented with phytosociological relevés, made in accordance with standard Central European methodology (Braun-Blanquet 1964). Plant nomenclature follows Flora Europaea (Tutin et al. 1964–1980, 1993).

Data analyses

Distribution data analyses

Data on the distribution of C. cinctus and its sister species were obtained from field studies, the literature and entomological collections. For each record, the following data were provided: locality and in brackets the name of the geographical region (e.g. Slavonia, Gorski Kotar, Istria, Primorje, Lika, Dalmatia and Dalmatian Zagora), date, year and data source. For certain records exact dates are missing, since they were not provided in the cited literature. In these cases, the year of publication was used as the date. Data sources include the literature citation and name of the entomological collection. Entomological collections of the Zadar National Museum (NMZ, Coleopteran collection), Split Natural History Museum (NHM, Novak Collection), and first author’s coleopteran collection were reviewed. The distribution data are presented and discussed in terms of three biogeographical regions: Alpine, Continental and Mediterranean (according to EEA 2015). Additionally, the data are classified in two categories: old and new records, the latter including records following the publication of the most recent catalogue of the carabid beetles of Croatia (Drovenik & Peks 1999). All records were georeferenced and distribution maps created in ArcGIS 10.2 (ESRI 2012).

Life-history trait analyses

Dominant species analysis was determined according to Tietze (1973). Species represented by > 5% in the assemblage are considered dominant. Seasonal activity was calculated on the number of specimens collected during one year. Since the number of pitfall traps and the sampling length varied between studied sites, the catch was standardised as the number of specimens per trap and per day. This was presented for two localities (Krčić River and Vrana Lake), while at the Nin saltpan it could not be shown due to the low number of sampled individuals. Activity density was compared between habitats, separately for each locality. This comparison was complicated due to the high number of samples with zero C. cinctus individuals, which made routine statistical tests inappropriate. To overcome excess-zero problems, we modelled observed count data using generalised linear models. A few models were tested to find the best fit for C. cinctus data, as there is no general model that would fit overdispersed soil animal data (Sileshi 2008). We used models assumed to be applicable for count data with excess zeros: Poisson model, zero-inflated Poisson model (ZIP; Lambert 1992), zero-inflated negative binomial model (ZINB; Martin et al. 2005) and negative binomial model (NBD; Lawless 1987). Goodness of fit was tested by Akaike’s information criterion (AIC; Johnson & Omland 2004). The activity density between habitats was then compared using likelihood ratio statistics. Pairwise comparisons were done for least squares means, using adjustment for multiple comparisons. Models were run using the SAS University Edition (SAS Institute Inc 2015) with the GLM procedure.

Sex of C. cinctus was determined on the basis of tarsus shape and genitalia. Sex ratio was compared using the nonparametric sign test run in Statistica 12 (StatSoft 2013). Ageing was based on elytral hardness and colour (van Dijk 1979). In this study, only two age categories were distinguished: tenerals and old adults. Teneral adults were recently hatched beetles, easily recognised by weak chitinisation and yellow-brownish elytra. Old adults were characterised by brown elytra and hard chitinisation. Flight ability was determined by hind wing development and all collected specimens were checked for hind wings. Two groups were recognised: short-winged (brachypterous) and long-winged (macropterous) specimens. Additionally, we measured elytron length (EL) and greatest wing length (WL). All proportions were measured using an eyepiece micrometer on a Zeiss Stemi 2000 microscope. Measurements were done according to Aukema (1990). A total of 50 specimens (40 brachypterous and 10 macropterous) from the Krčić area and 46 specimens (40 brachypterous and six macropterous) from Vrana Lake were measured. Differences in wing length (elytron and hind wings) between locations and sexes were tested using Mann–Whitney U test. The selection of the test depended on the normality data distribution, tested with the Shapiro–Wilk W test. These tests were performed in Statistica 12 (Statsoft Inc 2013).

Results and discussion

Distribution of Calathus cinctus and its sister species C. melanocephalus and C. mollis in Croatia

Calathus cinctus was recorded for the first time in Croatia along the river bed of the temporary Krčić River in 2014. It was not listed in the previous carabid beetle checklist (Drovenik & Peks 1999) or Catalogue of Palaearctic Coleoptera (Löbl & Smetana 2003) for Croatia. Additionally, revision of the Coleopteran collection of the Zadar National Museum revealed the occurrence of this species in other parts of Croatia (Figure 1a; Appendix 1). It was found in two biogeographical regions of Croatia: Alpine and Mediterranean (Appendix 1). In total, it was recorded at nine localities, with most records confined to the Mediterranean region. It was mainly found at lower altitudes up to 400 m, with the exception of the Alpine region, where it was recorded at 1060 m.

Figure 1. Distribution of the Calathus melanocephalus group in Croatia: (a) Calathus cinctus, (b) Calathus melanocephalus and (c) Calathus mollis. New records include data since 1999.

Calathus melanocephalus is present in all three biogeographical regions of Croatia: Alpine, Continental and Mediterranean (Figure 1b; Appendix 1). In total, it has been recorded at 31 localities and most findings were confined to the Continental biogeographical region. According to old literature data, this species was widespread through Dalmatia (Schlosser Klekovski 1875-77; Apfelbeck 1904; Sahlberg 1912-1913) and Slavonia (Schlosser Klekovski 1875-77). Additionally, it has been found on several mountains (e.g. Risnjak, Snježnik, Učka, Velebit; Appendix 1). However, in the previously cited literature, precise localities were not given. Interestingly, it was also recorded on the peak of Mt. Biokovo, (peak Sveti Jure, 1762 m; Vujčić-Karlo & Durbešić 2002). According to Aukema (1990), it is the only species of this group to occur at higher altitudes in the mountains.

Calathus mollis is present in all three biogeographical regions of Croatia: Alpine, Continental and Mediterranean (Figure 1c; Appendix 1). Most records have been confined to the Mediterranean region (35 localities), predominantly in southern Dalmatia, along the Adriatic coast and islands (Appendix 1). However, findings from other biogeographical regions were scarce. Similarly, this species is often abundant along the Atlantic coast in northern Europe (e.g. Lindroth 1992a; Anderson et al. 2000; Luff 2007; Desender et al. 2008) and along the Mediterranean coast (Ganglbauer 1892; du Chatenet 2005). It has primarily been found at lower altitudes, with the exception of the Plitvice Lakes (Alpine biogeographical region) at 560 m.

In Croatia, the distribution range of C. cinctus overlaps with the distribution ranges of its sister species, particularly in the Mediterranean and Alpine regions. Sympatry and mixed populations of C. cinctus and C. mollis were observed at the Vrana Lake sites. These findings are in accordance with observations from northern Europe where mixed populations were also observed (Aukema 1990).

Life history traits of Calathus cinctus

Habitat preferences

In total, 119 specimens of C. cinctus were sampled along the river bed of the temporary Krčić River. The majority of specimens were recorded in the karst habitats (90 specimens), while only 29 specimens were caught in the riparian habitats (Table I). Dominant species analysis showed that in karst habitats, C. cinctus belonged to the class of dominant species (8.63% of the total catch), while in riparian habitats it was rare with a frequency of ≤ 1% (A. Brigić, unpub. data). Based on goodness-of-fit criteria (Table II), the ZINB and NBD model best described the C. cinctus distribution. For both models, there was a statistically significant difference between two habitat types (karst and riparian habitats) in activity density (likelihood ratio test, NBD model: χ²(1) = 4.01, p < 0.05; ZINB model: χ²(1) = 4.11, p < 0.05). The Poisson model gave the worst fit to the data (Table II), corroborating Sileshi (2008).

Table II. Akaike’s information criterion (AIC) and Bayesian information criterion (BIC) for the tested models with statistical significance of differences between karst and riparian habitats (p value) of the Krčić River and Vrana Lake. For the description of habitat types see Table I. AIC and BIC are in the form “smaller is better”. Legend: ZIP: zero inflated Poisson model; ZINB: zero-inflated negative binomial model; NBD: negative binomial model.

Krčić River
Model	AIC	BIC	p
Poisson	424	429	< 0.0001
ZIP	284	291	< 0.0001
ZINB	218	227	0.0426
NBD	216	223	0.0452
Vrana Lake
Model	AIC	BIC	p
Poisson	264	275	< 0.0001
ZIP	266	279	< 0.0001
ZINB	194	210	< 0.0001
NBD	193	206	< 0.0001

In the surroundings of Vrana Lake, a total of 200 specimens of C. cinctus were caught. Most specimens were collected in arable land, e.g. 131 specimens in olive groves and 40 specimens in vineyards, followed by 17 specimens recorded in the Mediterranean shrublands. Similarly to riparian habitats of the Krčić River, C. cinctus was sporadically found in riparian habitats of Vrana Lake, e.g. six specimens in wet meadows and two specimens in reed beds. Goodness-of-fit criteria (Table II) showed that the ZINB and NBD models best described the C. cinctus distribution, similarly to the data from the Krčić River. Habitat type was a statistically significant predictor for activity densities (likelihood ratio test, NBD model: χ²(4) = 53.27, p < 0.001; ZINB model: χ²(4) = 53.27, p < 0.001). Pairwise comparisons (done for ZINB and NBD models) revealed significant differences in activity density between agricultural land and other habitats: wet meadows (p < 0.0001), Aleppo pine forest (p < 0.001), reed beds (p < 0.0001) and Mediterranean shrublands (p < 0.0001). Therefore, comparison of activity density via models for both locations clearly showed that C. cinctus is mainly a xerophilous species, preferring open thermophilous shrublands, pastures and arable land. These results are in accordance with Aukema (1990) and Luka et al. (2009).

In the Nin saltpan, only 23 specimens of C. cinctus were recorded. Most specimens were found on higher dikes (21 specimens), while a single specimen was recorded from the leeves directly above the salt pool during inundation. There were insufficient data to present the seasonal dynamic in the saltpan (catches: 14 specimens in May, eight in June and one in July) due to the large population of black-winged stilt nesting on the leeves, since adults, after some time, began to feed on soil invertebrates from the pitfall traps. Therefore, the trapping period ended before the end of summer and the expected autumn peak of this species’ activity was not recorded.

Overall, C. cinctus was recorded on different soil types along the Krčić River and around Vrana Lake (Table I). Most individuals were collected above terra rosa and dry brown soil forming shallow cover over limestone bedrock. Occasionally, it was also found above sandy soils. Similarly, C. cinctus was recorded above different soil types in northern Europe (Aukema 1990). Summarising the data on habitat properties (Table I), the most important predictor of C. cinctus habitat selection could be sun exposure, making the soil type a less relevant factor.

Seasonal activity

In both study areas, C. cinctus showed two activity peaks: in spring and in late autumn (Figure 2). In the sub-Mediterranean zone (Krčić River), the highest surface activity of beetles was observed in June and was associated with mature beetle activity and young beetle emergence. Generally, mature beetles were recorded throughout the season, while tenerals appeared in May (five individuals) and in June (11 individuals), the latter in accordance with Aukema (1990). After the spring peak, the number of beetles strongly decreased, with no beetles collected in August. The second peak of activity was detected in November and was determined by the activity of old beetles. Females dominated the catches along the Krčić River (76 females: 43 males) and the sex ratio differed significantly (sign test, p < 0.001). Overall, females were more active than males during the whole vegetation season.

Figure 2. Seasonal activity of Calathus cinctus in the sub-Mediterranean (Krčić River) and in the eu-Mediterranean (Vrana Lake) zones. Monthly catches in pitfall traps were pooled in both studied regions.

In the eu-Mediterranean zone (Vrana Lake), two peaks of activity were observed: at the end of winter and in autumn (Figure 2). The first peak of activity was already observed in March and was determined by mature beetle activity. After this peak, the number of beetles strongly decreased. Teneral adults were observed in April (two individuals) and in May (two individuals). Aestivation is likely to begin in July, since no beetles were collected during July and August. The highest surface activity of beetles was observed in November and was exclusively associated with the activity of mature beetles, while in Switzerland the autumn maximum was observed in October (Luka et al. 2009). The sex ratio did not differ significantly (102 females: 98 males; sign test, p > 0.05). Males were more active in January, May, September and November, while females were more active in March, April, June and October, implying that C. cinctus is an autumn breeder, as previously documented by Aukema (1990).

The present study showed that C. cinctus seasonal activity differed between the sub-Mediterranean and eu-Mediterranean zones, despite the close geographical proximity of the localities (less than 55 km air distance). Differences in seasonal patterns are highly likely to be due to the type of climate, the altitude and the vicinity of Mt. Dinara. Both climates are characterised by hot summers, with average maximum air temperatures as high as 41°C (Šegota & Filipčić 2003; Zaninović et al. 2008). In the sub-Mediterranean zone, the winters are cold, with a minimum average air temperature as low as −15°C, while in the eu-Mediterranean zone the air temperatures rarely fall below 0°C (Zaninović et al. 2008). Additionally, weather conditions in the sub-Mediterranean zone are also highly influenced by the vicinity of Mt. Dinara (Prelovšek 2010). Therefore, climatic conditions are more harsh and extreme in the sub-Mediterranean than in the eu-Mediterranean zone, causing a strong decrease in surface activity of C. cinctus and other carabid beetles in late autumn (A. Brigić, unpub. data), corroborating findings of Filippov (2006) for C. melanocephalus. Contrary to that, mild winter weather conditions enable surface activity and overwintering of C. cinctus mature adults in the eu-Mediterranean zone. Furthermore, our study showed that seasonal activity patterns of C. cinctus differ between northern (Aukema 1990) and southern populations, with seasonal activity beginning earlier in southern Europe. Similar patterns have been observed for other carabid beetle species, e.g. Carabus coriaceus Linné, 1758 (Dülge 1994; Kádár et al. 2015), Carabus germarii Sturm, 1815 (Paill 2000; Kádár et al. 2015) and Pterostichus strenuus Panzer, 1796 (Dülge 1994). The life cycle of some carabid beetle species may last 2 years (Matalin 2007), indicating that our data sets have some limitations. Therefore, in future studies, it would be interesting to focus on activity patterns of C. cinctus in a few consecutive years and to rear adults and larvae under different laboratory conditions, in order to estimate the duration and occurrence of individual development phases.

Flight abilities

Calathus cinctus populations both in the eu-Mediterranean and in the sub-Mediterranean zones are wing-dimorphic, having short- (brachypterous) and long- (macropterous) winged specimens (Table III), which corroborates results from northern Europe (Aukema 1990). In total, 111 specimens of C. cinctus recorded in the sub-Mediterranean zone (Krčić River) were brachypterous, while only eight specimens were macropterous (two males and six females). Similarly, brachypterous specimens (194 individuals) prevailed over macropterous (six individuals) in the eu-Mediterranean zone (Vrana Lake). Aukema (1990) demonstrated that C. cinctus shows a simple Mendelian inheritance pattern of wing morphology, with brachyptery dominant over macroptery. The relatively low proportion of macropterous specimens in both studied populations (6.72% in the Krčić area and 3.00% around Vrana Lake) suggests that these populations are stable and long established (Den Boer 1977; Lindroth 1992b).

Wing length in short-winged specimens was about 0.45 times the length of the elytron, while in long-winged specimens it was about 1.5 times the elytron length. Elytron and wing length differed significantly in size between the sexes (Mann–Whitney U test, elytron: U = 500.00, p < 0.001; wing length: U = 613.00, p < 0.001), while differences between locations were not significant (elytron: U = 940.00, p > 0.05; wing length: U = 1017.50, p > 0.05). Generally, females had longer wings than males and macropterous specimens had longer elytra than brachypterous specimens (Table III), which is in accordance with the findings of Aukema (1990). Hence, in comparison with this cited study, it was observed that both brachypterous and macropterous specimens (of both sexes) had longer wings in southern populations compared to populations in northern Europe, implying that C. cinctus individuals are longer in the Western Balkans than in northern Europe. A similar pattern has been observed for other carabid beetle species, e.g. Pterostichus rhaeticus (Brigić et al. 2014). In northern Europe, C. cinctus is considered a good disperser (Den Boer 1977). According to the present knowledge, its dispersal ability is unclear in the Mediterranean area, due to the high frequency of brachypterous specimens and no actual flight data, and remains to be tested in future studies, using other trapping methods (e.g. window traps or Malaise traps).

Table III. Measurements (mm) of short- and long-winged males and females of Calathus cinctus from the sub-Mediterranean (Krčić River) and eu-Mediterranean (Vrana Lake) area. Legend: SW: short winged; LW: longed winged; n: number of measured individuals; EL: elytron length; WL: maximum wing length; SD: standard deviation.

			EL			WL
	Locality	n	Min	Max	Mean ± SD	Min	Max	Mean ± SD
Males
SW	Krčić River	20	4.27	5.19	4.74 ± 0.24	1.37	2.38	2.05 ± 0.21
LW		2	4.90	7.35	6.00 ± 1.73	9.30	9.70	8.24 ± 1.41
SW	Vrana Lake	20	4.33	5.00	4.63 ± 0.20	1.89	2.44	2.09 ± 0.15
LW		3	4.64	5.00	4.80 ± 0.19	6.75	7.2	7.05 ± 0.26
Females
SW	Krčić River	20	4.21	5.49	4.92 ± 0.35	1.90	3.05	2.22 ± 0.26
LW		8	5.00	6.80	5.82 ± 0.79	7.00	9.60	8.18 ± 1.03
SW	Vrana Lake	20	4.56	5.43	4.99 ± 0.22	2.01	2.50	2.29 ± 0.13
LW		3	4.70	5.06	4.82 ± 0.21	6.23	7.13	6.71 ± 0.46

In conclusion, our study shows that C. cinctus is a common species in the Mediterranean area. It prefers open habitats, with sparse vegetation and sufficient insolation. The seasonal activity patterns are region-specific, governed by both a north–south gradient and regional climate conditions. Future studies should focus on dispersal abilities of C. cinctus, and the importance of wing morphology in (re-)establishment of new populations, particularly in unstable temporary river environments.

Acknowledgements

The authors would like to thank three anonymous reviewers for improving the manuscript, Bože Kokan for providing access to the Novak Collection (Split National History Museum), Zorana Sedlar for her assistance with ArcGIS and Linda Zanella for proofreading the English. Additionally, we would like to thank Vladimir Bartovsky, Gordan Lukač and Morana Bačić for assistance in field sampling. This study was supported by the University of Zagreb (Nos 202310, 202675 to Ivančica Ternjej) and by Zadar County and the Vrana Lake Nature Park (Snježana Vujčić-Karlo).

Additional information

Funding

This work was supported by the the University of Zagreb [grant numbers 202310; 202675]; Zadar County; and the Vrana Lake Nature Park.

Appendix 1

Distribution of Calathus cinctus and its sister species Calathus melanocephalus and Calathus mollis in Croatia. Legend: AB Collection: Andreja Brigić Collection; CNHM: Croatian Natural History Museum (Zagreb); NMZ: Zadar National Museum; VCM: Varaždin City Museum; NHM: Natural History Museum (Split).

Biogeographical region	Locality	Date	Year	Data source
Calathus cinctus
Alpine	Lazac (Mt. Risnjak, Gorski Kotar)	05.07.1991	1991	Coleoptera Collection (NMZ)
	Krčić River (Knin, Dalmatian Zagora)	21.05.2014;	2014	AB Collection
		23.06.2014;
		15.07.2014;
		24.09.2014;
		20.10.2014;
		20.11.2014
Mediterranean	Istarske Toplice (Istria)	29.07.1997	1997	Coleoptera Collection (NMZ)
	Lokva (Pelješac, Dalmatia)	13.10.1997	1997	Coleoptera Collection (NMZ)
	Ljubačko Blato (Zadar, Dalmatia)	20.06.2011	2011	Coleoptera Collection (NMZ)
	Nin saltpan (Nin, Dalmatia)	10.05.2011	2011	Coleoptera Collection (NMZ)
	Pakoška (Vrana Lake, Dalmatia)	21.12.2007	2007	Coleoptera Collection (NMZ)
	Tarac (Kornat Island, Dalmatia)	12.06.2009	2009	Coleoptera Collection (NMZ)
	Vrana Lake (Biograd, Dalmatia)	23.11.2007	2007	Coleoptera Collection (NMZ)
Calathus melanocephalus
Alpine	Fužine (Gorski Kotar)	09.09.1897;	1897;	Langhoffer (1886-1897);
		09.09.1897;	1897;	Koča Collection, CNHM – Gjurašin (2001);
		-	1929	Depoli (1929)
	Lič (Gorski Kotar)		1929	Depoli (1929)
	Ogulin (Gorski Kotar)		1929	Depoli (1929)
	Poljanak (Gorski Kotar)		1929	Depoli (1929)
	Ravna Gora (Gorski Kotar)		2012	Brigić (2012)
	Mt. Risnjak (Gorski Kotar)	12.10.1985	1985	Coleoptera Collection (NMZ)
	Mt. Snježnik (Gorski Kotar)		1929	Depoli (1929)
	Stara Sušica (Gorski Kotar)		2012	Brigić (2012)
	Mt. Velebit (Lika)		1899	Koča Collection, CNHM – Gjurašin (2001)
Continental	Bilje (Slavonia)		2008	Tallósi (2008)
	Gotalovo (Koprivnica, Podravina)		2008	Tallósi (2008)
	Kamenica (Hrvatsko Zagorje)	27.05.1934	1934	Košćec Collection, VCM – Bregović (1985), Bušnja (2008)
	Kantrida (Rijeka, Primorje)		1929	Depoli (1929)
	Mužilovčica (Lonjsko Polje, Slavonia)	18.09.2002	2002	AB Collection
	Modruš (Karlovac, Kordun)	22.08.1888	1988	Koča Collection, CNHM – Gjurašin (2001)
	Novačka (Koprivnica, Podravina)		2008	Tallósi (2008)
	Novo Virje (Podravina)		2008	Tallósi (2008)
	Paukovec (Hrvatsko Zagorje)	17.06.1907	1907	Košćec Collection, VCM – Bregović (1985), Bušnja (2008)
	Repaš (Podravina)		2008	Tallósi (2008)
	Rijeka (Primorje)		1929	Depoli (1929)
	Sakadaš Lake (Kopački Rit, Slavonia)		2009	Domić (2009)
	Slavonia		1875–77	Schlosser Klekovski (1875-77)
	Trnje (Zagreb)	08.08.1901	1901	Koča Collection, CNHM – Gjurašin (2001)
	Mt. Ućka (Primorje)		1929	Depoli (1929)
	Varaždin (Hrvatsko Zagorje)	19.05.1912; 21.09.1918; 03.06.1919; 03.06.1919; 28.06.1921; 03.06.1923; 15.06.1930; 27.06.1934; 17.08.1940; 14.09.1947; 12.09.1949; 18.04.1950; 21.07.1950; 17.07.1951	1912; 1918; 1919; 1919; 1921; 1923; 1930; 1934; 1940; 1947; 1949; 1950; 1950; 1951	Košćec Collection, VCM – Bregović (1985), Bušnja (2008)
	Vinkovci (Slavonia)		1906	Koča (1905)
	Zagreb	28.04.1904	1904	Koča Collection, CNHM – Gjurašin (2001)
	Zbelava (Varaždin, Hrvatsko Zagorje)		1996–1997	Durbešić et al. (2006)
	Zmajevac (Slavonia)		2008	Tallósi (2008)
Mediterranean	Dalmatia		1875–77; 1904; 1912–1913	Schlosser Klekovski (1875-77); Apfelbeck (1904); Sahlberg (1912-1913)
	Dugopolje (Split, Dalmatia)	09.06.1921	1921	Novak (1964)
	Galičak (Ploče, Dalmatia)	08.08.1996	1996	Kučinić et al. (1996)
	Istarske Toplice (Istria)	29.07.1997	1997	Coleoptera Collection (NMZ)
	Jasenice (Zadar, Dalmatia)	27.04.1914	1914	Novak (1964)
	Mt. Biokovo – peak Sveti Jure (Dalmatia)		1992–1993	Vujčić-Karlo and Durbešić (2002)
	Palagruža Island (Dalmatia)	19.05.1949	1949	Novak (1964, 1970)
	Velo Blato (Pag Island, Primorje)	01.04.2007	2007	Coleoptera Collection (NMZ)
Calathus mollis
Alpine	Plitvice Lakes (Lika)		1958	Kovačević (1958)
Continental	Varaždin (Hrvatsko Zagorje)	09.09.1921	1921	Košćec Collection, VCM – Bušnja (2008)
Mediterranean	Baćinska Lakes (Dalmatia)	14.04.1993	1993	Coleoptera Collection (NMZ)
	Banja (Komin, Dalmatia)	12.10.1997	1997	Coleoptera Collection – NMZ
	Biševo Island (Dalmatia)		1952; 1970; 1986	Novak (1952, 1970); Marcuzzi (1986)
	Bokanjac (Zadar, Dalmatia)		1910	Novak Collection – NHM Split
	Cres Island (Primorje)		1929; 1952; 1970	Depoli (1929); Novak (1952, 1970)
	Dalmatia		1904; 1912–1913	Apfelbeck (1904); Sahlberg (1912-1913)
	Dragović (Peruča Lake, Dalmatian Zagora)		1910	Novak Collection – NHM Split
	Galičak (Ploče, Dalmatia)	14.07.1994; 12.10.1997	1994; 1997	Coleoptera Collection (NMZ)
	Jarebinka Pit (Kozjak Mountain, Split, Dalmatia)	21.04.2001	2001	Coleoptera Collection (NMZ)
	Kantrida (Rijeka, Primorje)		1929	Depoli (1929)
	Kaštel Kambelovac (Dalmatia)		1986	Marcuzzi (1986)
	Kaštela (Split, Dalmatia)		1910	Novak Collection – NHM Split
	Knin (Dalmatian Zagora)	09.1899	1899	Novak (1952)
	Komiža (Vis Island, Dalmatia)		1986	Marcuzzi (1986)
	Kosore (Vrlika, Dalmatia)	09.1901	1901; 1910	Novak (1952); Novak Collection – NHM Split
	Lapad (Dubrovnik, Dalmatia)	03.1916	1916	Novak (1952)
	Lastovo Island (Dalmatia)		1986	Marcuzzi (1986)
	Lošinj Island (Primorje)		1952	Depoli (1929); Novak (1952, 1970)
	Marjan (Split, Dalmatia)	19.10.2003; 08.04.2005	2003; 2005	Coleoptera Collection (NMZ)
	Metković (Dalmatia)		1904	Apfelbeck (1904)
	Opatija (Primorje)		1929	Depoli (1929)
	Palagruža Island (Dalmatia)	19.05.1949	1949; 1970	Novak (1952, 1970)
	Premantura (Istria)		1922	Müller (1922)
	Pristeg (Zadar, Dalmatia)	26.10.1904	1904	Novak (1952)
	Rab Island (Primorje)		1929; 1952; 1970	Depoli (1929); Novak (1952, 1970)
	Solin (Dalmatia)	06.1912	1912	Novak (1952)
	Split (Dalmatia)		1926;	Hoffmann (1926); Novak Collection – NHM Split
	Susak Island (Primorje)		1922; 1929; 1952; 1970	Müller (1922); Depoli (1929); Novak (1952, 1970)
	Sv. Andrija Island (Dalmatia)		1914; 1952; 1970	Müller (1914); Novak (1952, 1970)
	Krševo Polje (Telašćica Bay, Dugi Otok Island, Dalmatia)	12.10.2006; 30.11.2006	2006; 2006	Coleoptera Collection (NMZ)
	Unije Island (Primorje)		1929; 1952; 1970	Depoli (1929); Novak (1952, 1970)
	Vis Island (Dalmatia)		1910; 1911; 1911; 1914	Novak Collection – NHM Split; Novak (1952, 1970); Müller (1914)
	near Zrmanja River (Zadar, Dalmatia)	13.07.1926	1926	Novak (1952)
	Žminj (Opatija, Primorje)		1929	Depoli (1929)