Natrix Tessellata Research Articles

MELANISM IN NATRIX NATRIX AND NATRIX TESSELLATA (SERPENTES: COLUBRIDAE) FROM MONTENEGRO

This article present melanism in two species: Natrix natrix (Linnaeus, 1758) and Natrix tessellata (Laurenti, 1768) from Montenegro.

A global overview on the diet of the dice snake (Natrix tessellata) from a geographical perspective: foraging in atypical habitats and feeding spectrum widening helps colonisation and survival under suboptimal conditions for a piscivorous snake

AbstractBackgroundThe dice snake (Natrix tessellataLaurenti, 1768) is generally considered to be a fully or partially piscivorous freshwater snake species. The aim of the study was to make the first global overview on the taxonomy and geographical distribution of the species based on own observations, available databases and the special literature.ResultsBesides freshwaters,N. tessellataturned out to hunt also in marine and terrestrial habitats predating on at least 29 and 15 species, respectively. On the basis of our data and the literature altogether, 113 prey taxa, mostly fish, were listed but 20% of them were invertebrates, amphibians, reptiles and mammals. The importance of non-fish species in the diet was especially pronounced in deserts, high mountains and in dry Mediterranean areas. In spite of the wide feeding spectrum, only fish and amphibians were found to be predominant food items over the whole species' range. Fish dominated the catch of the dice snake in most quantitative studies, except one survey in Turkey, where the ratio of non-fish prey items was over 50%.ConclusionsThe global analysis of the diet of the dice snake revealed a feeding spectrum characteristically changing over the broad distribution area including non-fish prey as well as taxa from marine and terrestrial habitats. The analysis of the feeding spectrum separated four large geographical units with further distinctions in Central and Eastern Europe. Such diversity helps explain why this species was able to colonise a large and diverse Eurasian range.

Анализ изменчивости морфологических признаков водяного ужа (Natrix tessellata) Волгоградской области

Анализ изменчивости морфологических признаков водяного ужа (Natrix tessellata) Волгоградской области

Hypernatremia in Dice snakes (Natrix tessellata) from a coastal population: implications for osmoregulation in marine snake prototypes.

The widespread relationship between salt excreting structures (e.g., salt glands) and marine life strongly suggests that the ability to regulate salt balance has been crucial during the transition to marine life in tetrapods. Elevated natremia (plasma sodium) recorded in several marine snakes species suggests that the development of a tolerance toward hypernatremia, in addition to salt gland development, has been a critical feature in the evolution of marine snakes. However, data from intermediate stage (species lacking salt glands but occasionally using salty environments) are lacking to draw a comprehensive picture of the evolution of an euryhaline physiology in these organisms. In this study, we assessed natremia of free-ranging Dice snakes (Natrix tessellata, a predominantly fresh water natricine lacking salt glands) from a coastal population in Bulgaria. Our results show that coastal N. tessellata can display hypernatremia (up to 195.5 mmol.l−1) without any apparent effect on several physiological and behavioural traits (e.g., hematocrit, body condition, foraging). More generally, a review of natremia in species situated along a continuum of habitat use between fresh- and seawater shows that snake species display a concomitant tolerance toward hypernatremia, even in species lacking salt glands. Collectively, these data suggest that a physiological tolerance toward hypernatremia has been critical during the evolution of an euryhaline physiology, and may well have preceded the evolution of salt glands.

High helmintic infection of the European grass snake, Natrix natrix and the dice snake, Natrix tessellate (Serpentes: Colubridae) from Iran

ObjectiveTo determine the helminth parasites of Natrix natrix Linnaeus, 1758 (N. natrix) and Natrix tessellata Laurenti, 1768 (N. tessellate) in north of Iran. MethodsEighteen snakes including nine N. natrix and nine N. tessellata from Mazandaran Province, north of Iran were collected and examined during March 2011 to October 2011 for helminth parasites. The collected specimens were fixed and preserved in 70% ethanol. ResultsAll of the examined snakes (100%) were infected with parasitic helminth. The list of extracted helminths both in N. natrix and N. tessellata includes one Nematode: Rhabdias fuscovenosa (larva), one Digenea: Telorchis assula and one Cestoda: Ophiotaenia europaea. The infection rate of Ophiotaenia europaea, Telorchis assula and Rhabdias fuscovenosa (larva) from collected snakes were 100%, 83.3% and 61.1%, respectively. Moreover, in the current investigation the morphological characteristics of the collected helminths were described elaborately. ConclusionsThis is the first survey on helminth parasites from N. tessellata in Iran and the helminthes are reported for the first time from this host in Iran.

Changes in the Nothern Border of the Home Range of the Dice Snake, Natrix Tessellata (Reptilia, Colubridae), in the Dnipro Basin (Ukraine)

Abstract A new distribution boundary of the dice snake, Natrix tessellate (Laurenti, 1768), in Ukraine has been established. The northern edge currently lies within the valley of the middle course of the Dnipro River: Trakhtemyriv Peninsula, Cherkasy Region on the right side (49°59′ N, 31°25′ E); on the left side in Kyiv Region within Pereyaslav-Khmelnytsky District: at a fishermen’s station (50°02' N, 31°17' E), yacht club (Kurinoye Estuary 50°02′ N, 31°29′ E); Lubny, Poltava Region (49°58 N, 33°01′ E). These points are located 70-80 km northwards from the previous boundary of the species home range. The level of Natrix tessellata population polymorphism in the North of Cherkasy Region is high; more than 40 % of specimens are dark-colored.

Seasonal Diet of the Otter ( Lutra lutra ) On the Alazani River (Georgia)

The seasonal diet of the otter ( Lutra lutra ) was studied on Alazani river in eastern Georgia using scat analysis. The frequency of occurrence (FO) of prey items and, for fish species, biomass consumed (BC) were estimated. Fish and amphibians made the bulk of the otter diet in the study area (49.8-30.0% FO and 23.6-36.2% FO, respectively). Reptiles were also important in otter diet (11.5% and 13.4%). Mammals, birds, insects, mollusks and crayfish were of minor importance. Crucian carp (Carassius carassius) and common carp were the most important fish in the otter diet. Among amphibians, only Rana ridibunda were found; among reptiles, only dice snake and grass snake were found in otter spraints. All mammals preyed upon by otters were rodents; mice (69% of all mammals) and muskrat (31%). Water beetles ( Dytiscidae ) and grasshoppers ( Acridoidea ) were the main group of insects consumed by otters. Seasonal food niche breadth change was expressed strongly (B A = 0.260 in cold season vs. B A = 0.492 in the warm season). Crucian carp predominated in the diet in both warm (37.9% BC and 52.0% FO, respectively) and cold season (90.4% BC and 82.0% FO, respectively). C. idella and S. glanis were found during the warm season but almost disappeared from the otter diet in the cold season. Rutilus rutilus and Hypophthalmiehthys molitrix were of minor importance in both seasons. Download the complete issue.

The Herpetology of the Suez Canal Zone, Egypt

The banks of the Suez Canal were surveyed for herpetofauna between 1999 and 2012. A total of 33 species from the west bank, 22 from the east and a sea turtle from the Suez Canal were recorded, with five and 18 new records from the west and east sides respectively. Natrix tessellata, inhabiting freshwater canals east of Bitter Lakes, is the first record for the Sinai Peninsula. The new records of amphibians and reptiles of the Suez Canal area are, in fact, a result of recent main changes to habitat. These new environmental changes have resulted in some cases, in more invasive herpetofaunal taxa expanding their ranges into new territories over the past three decades. The number of species occurring on the west bank was greater than on the east bank; this is presumably due to greater variety of habitat, increased urbanization, and a huge web of irrigation canals which have allowed several species to move from River Nile to the Canal zone. This study suggests the Suez Canal acts as passage for herpetofauna from west to east. Individuals of Trapelus savignyi on the west bank were patternless and juveniles had smooth ventrals. This phenotype was not previously known for the species.

Direct and Indirect Interactions between an Invasive Alien Fish (Perccottus glenii) and Two Native Semi-aquatic Snakes

The ecological links of aquatic invasive fish and native reptiles are rarely studied. Thus, we analyzed the diet and helminth composition of a recently introduced invasive alien fish (the Rotan, Perccottus glenii) and of two native semi-aquatic snakes (the Dice Snake Natrix tessellata, the Grass Snake N. natrix) in Cranberry Lake, Russia. We also studied diet and helminthes of water frogs (Pelophylax spp.) as a potential mechanism of transmission of parasites. We identified 19 prey taxa and four helminthes for P. glenii, 21 and 24 for Pelophylax spp., and two and 16 for the snakes. The piscivorous N. tessellata has been feeding on P. glenii since its introduction and the subsequent elimination of native fish. Although we did not find P. glenii in the diet of the mainly frog-eating N. natrix, helminth analysis indicated that this snake may prey upon this fish. Both studied snakes contracted the parasitic tapeworm Ophiotaenia europaea from P. glenii. Therefore, the invasive fish and the native snakes demons...

Comparative phylogeography reveals distinct colonization patterns of Cretan snakes

AbstractAimWe assessed genetic relationships among populations for each of the four snake species found on Crete (Zamenis situla, Hierophis gemonensis, Telescopus fallax and Natrix tessellata), including conspecific populations from the Aegean area. Our aim was to reconstruct their phylogeographical histories, especially regarding their occurrence on Crete.LocationCrete, Aegean Sea and eastern Mediterranean.MethodsGenetic diversity and relationships were based on sequences of the mitochondrial marker cytochrome b, applying phylogenetic analyses (maximum likelihood, Bayesian inference and neighbour‐joining), a median‐joining network analysis and a molecular dating analysis.ResultsThe Z. situla phylogeny includes a clade with specimens from Crete, the Peloponnese and Thera, while specimens from Turkey, northern Greece and the eastern Aegean islands form a separate clade. The H. gemonensis tree also presents two clades: one comprising specimens from Crete and Kythera, and another representing the continental part of the species' distribution. For N. tessellata, Cretan populations are found as the sister clade to populations from Europe and western Turkey. A more complex genetic structure is found in T. fallax: specimens from Crete, Thera and Antikythera form a clade, which itself forms part of a ‘western’ clade, and an ‘eastern’ clade includes specimens from Turkey, the eastern Aegean islands and Cyprus. The splits resulting in the Cretan clades for T. fallax and N. tessellata occurred at the end of the Miocene and the Pliocene/Pleistocene boundary, respectively. The Cretan lineages of H. gemonensis and Z. situla diversified during the Pleistocene.Main conclusionsZamenis situla and H. gemonensis exhibit a phylogeographical pattern that involves a transmarine dispersal from southern continental Greece to Crete (possibly by humans in the case of Z. situla). The occurrence of T. fallax on Crete is explained by a natural dispersal from the west and isolation by vicariance. Although these two patterns have also been inferred for other studied herptiles of Crete, the pattern in N. tessellata is unique and involves a transmarine dispersal from south‐western Turkey to Crete.

Unexpected life history traits in a very dense population of dice snakes

A population of dice snakes (Natrix tessellata) monitored since 2008 in a small island (18ha, 850m a.s.l., FYR of Macedonia) revealed unforeseen patterns for snakes living in temperate climates. More than 5000 individuals have been marked and the density is one of the highest ever recorded (>500 resident snakes per hectare). Reproductive and mortality rates are elevated, suggesting a high population turnover. These traits evoke a tropical rather than a temperate-climate ophidian demographic system. The population is highly polymorphic, three colour morphs (dotted, grey, and black) are observed in both sexes and each morph is represented by large numbers of individuals. This polymorphism pattern was not previously documented in snakes. Data obtained for other life history traits (e.g. body size, size at maturity, clutch size, diet, predation) markedly diverged in comparison to available information. Overall, our results reinforce the notion that the strong inter-population variability (often mediated by phenotypic plasticity) of snakes should be taken into account over large geographic scales; otherwise attempts to derive general patterns may well be strongly biased.

The First Case of Ophionyssus natricis (Gervais, 1844) on a Sea Snake (Natrix tessellata, Laurente 1768) (Reptilia: Squamata: Colubridae) in Turkey

This study was carried out to increase information about Ophionyssus natricis (Gervais, 1844) detected on the sea snake (Natrix tessellata). The mite individuals collected from the cage of a sea snake were brought to our laboratory by the owner of the snake. They werepreserved in 70% alcohol, and then the mites were mounted on slides in Canada balsam, after making them transparent in lacto phenol for a few days. They were identified to species in respect of their morphological characters under the light microscope. A total of nine mite individuals were collected from the cage of a sea snake, and all of them were identified as Ophionyssus natricis as the result of microscopical examination. Ophionyssus natricis was recorded from the sea snake for the first time in Turkey. knowledge about this mite is provided in this paper.

Comparative Morphology of the Skin ofNatrix tessellata(Family: Colubridae) andCerastes vipera(Family: Viperidae)

We studied beneficial difference of the skin of two snakes. Two snakes were chosen from two different habitats and two families: Colubridae (Natrix tessellata) and Viperidae (Cerastes vipera). The investigations were performed by light and electron microscopy. Histologically, the skin of the studied species show pronounced modifications that correlated with functional demands. The scales in Natrix tessellata overlapped slightly, while in Cerastes vipera they were highly overlapped. SEM shows that scales of Natrix tessellata had bidentate tips while the scales of Cerastes vipera were keeled. Histochemically, in both studied species, melanocytes and collagenous fibres were distributed throughout the dermis. Polysaccharides were highly concentrated in the epidermis and dermis of both species while proteins were highly concentrated only in the epidermis. Transmission electron microscopy (TEM) showed that the skin of both snakes consisted of keratins located in the epidermis. Some lipids and mucus were incorporated into the outer scale surfaces such that lipids were part of the fully keratinised hard layer of the snakes' skins. Lipids are probably responsible for limiting water loss and ion movements across the skin. Melanosomes from epidermal melanocytes were present only in Cerastes vipera. In aggregate, these results indicate that snakeskin may provide an ecological indicator whereby epidermal and integumentary specializations may be ecologically correlated.

Long‐term population dynamics in a Mediterranean aquatic snake

AbstractA review of several long‐term studies has recently suggested that snakes might be declining in large parts of the world. Additional data from other long‐term studies are therefore urgently needed in order to assess the generalities of such suggested declines. Based on a 20‐year study, we analyzed demographic data on adult dice snakes (Natrix tessellata) studied in central Italy between 1985 and 2004. Both male and female dice snakes were relatively long‐lived, with no significant differences in longevity between the sexes. Individual males and females were observed over a maximum of 10 and 14 years, respectively. However, the among‐year recapture rates between the year the snakes were initially captured and the subsequent year (i.e., year 1 to year 2) was significantly lower (45%) than the among‐year recapture rates during subsequent years (74%; i.e., year 2 to year 3), suggesting that a large proportion of the snakes at first capture were in fact not resident within our study area, and hence many snakes were migrating in and out of our 2‐km stream study site, with no inter‐sexual difference in dispersal rates. Sex ratio was virtually equal if we consider the study period as a whole. Significant annual fluctuations were, however, observed through the study. In 1985–1990, 1993–1995, 1998 and 1999 the sex ratio was male‐biased, whereas in 2000–2004 female‐biased. In terms of both survival and recapture probabilities, model selection showed that Akaike's information criterion favored the model incorporating body size, with the model incorporating year having an intermediate likelihood, and the model with sex included being the most disfavored. Total population number estimates suggest an average 86 adult individuals along the 2 km of stream with only minor annual variations. However, a significant decrease in the number of males occurred during the last 6 years of our study. Thus, further monitoring of this population is warranted in light of the decline of snake populations reported recently.

Faunistic studies on snakes of West Golestan state

The aim of present research was to study the snake fauna of western parts of Golestan province; from Gorgan city up to the border of Mazandaran province; by analysing the morphological characters and using identification keys. The studies were undertaken during 2008-2009. A total of 36 specimens were collected. These included 11 species belonging to 10 genera and 4 families; Natrix tessellata, Natrix natrix, Elaphe dione, Hemorrhois ravergieri, Dolichophis jugularis, Platyceps najadum, Telescopus fallax and Zamenis persica from Colubridae family, Typhlops Vermiculari from Typhlopidae family, Naja oxiana from Elapidae, Gloydius halys caucasicus from Viperida. Scaterred map of each species was plotted.

A brief review of morphological variation in Natrix tessellata in Israel: between sides, among individuals, between sexes, and among regions

After introducing the distribution and biology of Natrix tessellata in Israel, on the southern edge of its range, we address its intraspecific variation from the literature and examination of 262 museum specimens. Head pholidosis showed no significant directional asymmetry, but asymmetry in infralabial plates was significantly correlated with frequency of injured tails. Variation in body size showed no clear seasonal growth, presumably due to climatic fluctuations. The variation in number of ventrals (in males, 159-173, mode 165) was not geographical. Females attained 750-800 mm (head and body; mode 600-650) and males 700-750 (mode 500-600) mm. Females had significantly greater relative head length, and males significantly greater eye size relative to head length, counts of ventrals and of subcaudals, and relative tail length. The sexual dimorphism in relative tail length was evident also in juveniles. The sexual dimorphism varied geographically within Israel: that of head size was stronger in the south, that of relative tail length and number of subcaudals stronger in the north. Trunk coloration commonly comprised 6 rows of blackish spots of equal or different size. Head coloration in some individuals extraordinarily resembled that of Natrix natrix. We discuss some methodological problems and compare variation within Israel and with Anatolia.

Are gobiid fish more susceptible to predation if parasitized byEustrongylides excisus? An answer from robbed snakes

AbstractAspects of the predator–prey relationship between dice snake,Natrix tessellataand gobiid fish infected withEustrongylides excisuswere studied in Lake Sinoe, Romania. A population of snakes residing here shows a high prevalence of subcutaneous larvae of this nematode. The hypothesis of the altered motility in infected fish leading to increased depredation by snakes was tested by comparing gobiids collected from dice snakes with gobiids caught via electrofishing. Out of a total of seven identified gobiid species, three were used for analysis: syrman gobyNeogobius syrman, mushroom gobyNeogobius eurycephalus, and round gobyNeogobius melanostomus. No significant differences in prevalence and intensity ofE.excisusinfection were found between fish caught by snakes and those obtained by electrofishing. However, significantly higher abundance ofE.excisuslarvae in fish caught by snakes was reported. These findings suggest limited influence of the presence ofE.excisuslarvae in studied gobiids regarding their susceptibility to predation by dice snakes.

Calculation of Fluctuating Asymmetry of the biggest Caspian whipsnake population in Hungary compared to a common snake species

The Fluctuating Asymmetry (FA) is a special type of asymmetry in the populations of bilaterally symmetrical creatures. The FA gives us numerical data on the developmental instability of the populations and refers to potential genetical and environmental stressors affecting the populations. Here we give the first data on the FA of the protected Caspian whipsnake (Hierophis caspius) from Hungary. The FA indices of the biggest population from Villany Mts were compared to the FA indices of two differently stressed Dice snake (Natrix tessellata) populations [stressed (Mad) and seminatural (Lake Balaton)]. Based on the values of the multiple and the simple indices derived from sublabial scales, we can say that the status quo of the highly protected Caspian whipsnake population does not represent significant deviation from the near-natural dice snake population from the Lake Balaton.

Cryptic diversity in a Eurasian water snake ( Natrix tessellata, Serpentes: Colubridae): Evidence from mitochondrial sequence data and nuclear ISSR-PCR fingerprinting

The dice snake, Natrix tessellata (Laurenti, 1768), is a suitable study organism to address questions of Eurasian phylogeography due to its wide Palearctic distribution. We analysed complete mitochondrial cytochrome b sequences and nuclear ISSR-PCR fingerprints of more than 300 specimens representing nearly the entire geographic range. Nine major mitochondrial lineages were discovered based on mtDNA sequences. The three most basal lineages comprised populations from Iran, Jordan–Egypt, and Greece, respectively. Other lineages were associated with samples from the Turkish peninsula, the Caucasus, the Aral Sea, and eastern Kazakhstan. A sister-group relationship was found between two lineages from Crete and the European mainland. Assuming an evolutionary rate of 1.35% sequence divergence per million years, among-lineage p-distances of 1.7–8.4% suggest that intraspecific differentiation might date back as far as the Miocene/Pliocene transition 5–6 million years ago. The pattern of genetic differentiation in mitochondrial phylogeny with regard to Asia Minor and the region of the Aral Sea was not congruent with the results of the nuclear ISSR-PCR analyses, and suggests admixing within some mtDNA clades at contact zones. The taxonomic implications of the high intraspecific variation in the dice snake are discussed.

Novel microsatellite loci in the grass snake (Natrix natrix) and cross‐amplification in the dice snake (Natrix tessellata)

Six novel polymorphic microsatellite loci are presented for the grass snake (Natrix natrix), a species with declining populations in many regions. The number of alleles per locus ranged from two to seven. Four dice snake (Natrix tessellata) microsatellites were polymorphic in the grass snake with three to four alleles. At two loci, the expected heterozygosity differed significantly from observed heterozygosity. Cross-amplification of the grass snake markers in the dice snake showed two polymorphic microsatellites with two and four alleles.