Natrix Research Articles

New Data on the Larval Stages of Leptophallus nigrovenosus (Digenea, Plagiorchiata).

(1) Background: Leptophallus nigrovenosus, an esophageal parasite that primarily affects water snakes of the genus Natrix, has a known life cycle that involves snail and amphibian hosts. However, the biological aspects, chaetotaxic patterns, and pathogeny of this parasite in its hosts have not been fully elucidated. (2) Methods: Snails (Planorbarius metidjensis) were collected in Spain and examined for cercaria emergence. The larvae were used to experimentally infect Salamandra salamandra, and metacercariae were isolated. Their chaetotaxy was studied using microscopy and scanning electron microscopy. The eye histology was also examined. (3) Results: The cercariae displayed distinctive morphological characteristics. The results of this study revealed three types of ciliated sensory papillae on the cercarial teguments, suggesting an adaptation for host detection and orientation. The metacercariae isolated from subcutaneous tissues showed oval bodies covered in spines. The chaetotaxy patterns matched those of Leptophallinae species. This is the first report of the presence of L. nigrovenosus in the snail P. metidjensis. Additionally, this study detected metacercariae in the eyes of S. salamandra, emphasizing the need for further research on trematode infections in amphibian eyes. (4) Conclusions: Members of the genus Salamandra can serve as secondary intermediate hosts for L. nigrovenosus, and the presence of metacercariae in amphibian eyes may have implications for the survival and habitat management of these amphibians. Understanding this parasite's prevalence, transmission dynamics, and impacts on host populations is crucial for conservation strategies.

Distribution of the grass snake (Natrix natrix) and dice snake (N. tessellata) in Bulgaria

We summarise the distribution of the two species of the genus Natrix occurring in Bulgaria, based on records from 147 peer-reviewed publications, grey literature, and data repositories, combined with unpublished data. This is the first extensive mapping for N. natrix; records fall in 560 cells of the 10-km MGRS/UTM grid, of which 102 cells (18.2%) were with published information we could not confirm with new data, 175 (31.2%) were with published and confirmed, and 283 (50.5%) were with new localities. For N. tessellata we increased the number of cells with records by 64% compared to the 2011 mapping, by identifying 445 cells with localities: 162 cells (36.4%) were previously published and unconfirmed, 152 (34.1%) were published and confirmed, and 131 (29.4%) were with new data. Gross climatic conditions for records with exact locations were assigned following the Köppen-Geiger classification; the distribution for both species does not seem to be highly correlated to climate as they were found in 9 of the 12 Köppen-Geiger classes present, only missing from the 3 classes that are limited to high elevations in Bulgaria and account for less than 1% of the area. The vertical distribution of the observations supports our knowledge that the species are most numerous at lower elevations (92.4% of records were <1000 m above sea level for N. natrix and 92.6% were <500 m for N. tessellata). Higher elevations and some lowlands remain relatively understudied and future sampling will likely reveal new localities for both species.

Genomics reveals broad hybridization in deeply divergent Palearctic grass and water snakes (Natrix spp.)

Understanding speciation is one of the cornerstones of biological diversity research. Currently, speciation is often understood as a continuous process of divergence that continues until genetic or other incompatibilities minimize or prevent interbreeding. The Palearctic snake genus Natrix is an ideal group to study speciation, as it comprises taxa representing distinct stages of the speciation process, ranging from widely interbreeding parapatric taxa through parapatric species with very limited gene flow in narrow hybrid zones to widely sympatric species. To understand the evolution of reproductive isolation through time, we have sequenced the genomes of all five species within this genus and two additional subspecies. We used both long-read and short-read methods to sequence and de-novo-assemble two high-quality genomes (Natrix h. helvetica, Natrix n. natrix) to their 1.7 Gb length with a contig N50 of 4.6 Mbp and 1.5 Mbp, respectively, and used these as references to assemble the remaining short-read-based genomes. Our phylogenomic analyses yielded a well-supported dated phylogeny and evidence for a surprisingly complex history of interspecific gene flow, including between widely sympatric species. Furthermore, evidence for gene flow was also found for currently allopatric species pairs. Genetic exchange among these well-defined, distinct, and several million-year-old reptile species emphasizes that speciation and maintenance of species distinctness can occur despite continued genetic exchange.

Adaptive reactions of the blood system of Elaphe dione, Natrix natrix, and N. tessellata (Reptilia: Colubridae)

A comparative interspecific assessment of the leukocyte profile of young Elaphe dione, Natrix natrix and N. tessellata is given. Juvenile snakes were obtained in captivity from females captured, being pregnant, from Volga populations. Eosinophils and basophils predominated in the blood of young E. dione, the total content of mononuclear cells (agranulocytes) was lower compared to the young of N. tessellata and N. natrix. At the same time, the species of the genus Natrix differed in the content of all three types of mononuclear cells, namely: the proportion of azurophils and monocytes was higher in N. tessellata, and that of lymphocytes was higher in N. natrix. The main contribution to the balance of mononuclear cells was made by lymphocytes. The leukocyte composition of young snakes had no pronounced lymphocytic profile, the contribution of the specific reactivity of the organism to the overall adaptive response of the body of young snakes to environmental conditions was small. According to the content of lymphocytes, the studied species were arranged in descending order in the following row: N. natrix (Me – 60.00, IQR – 2.50) → N. tessellata (52.00, 6.00) → E. dione (40.00, 5.00). The increased value of the leukocyte shift index in E. dione young testified to the predominant role of granulocytes in the immune response with some lag of lymphocyte-monocyte cells and later activation of the effector link of the immune response (lymphocytes) compared with young of N. natrix and N. tessellata. While the specific reaction of the immune system decreased, a compensator activation of the nonspecific protective blood system was observed in the organism of E. dione. The increase in the content of granulocytes in the blood of young snakes was a characteristic indicator of an increase in environmental stress, assessed by the integral leukocyte index (the ratio of heterophiles and lymphocytes). Integral leukocyte indices reflected an imbalance of the adaptive response of the blood system in young snakes kept in captivity in relation to adult males and females from natural populations.

The valid scientific names of the barred grass snake and its subspecies from mainland Italy and Sicily

Abstract To stabilize current nomenclature, Coluber helveticus Lacepède, 1789 and Coluber siculus Cuvier, 1829 are qualified as nomina protecta to ensure the usage of the established names Natrix helvetica (Lacepède, 1789) and Natrix helvetica sicula (Cuvier, 1829) for the barred grass snake. For the same reason, Coluber bipes Gmelin, 1789, Coluber tyrolensis Gmelin, 1789 and Coluber scopolianus Daudin, 1803, all with type locality Dolomiti di Fiemme (Italy), are declared as nomina oblita according to Article 23.9 of the International Code of Zoological Nomenclature (1999). Coluber helveticus Lacepède, 1789 was originally introduced as a replacement name for Coluber vulgaris Razoumowsky, 1789 (type locality: Jorat, Switzerland). However, the latter name becomes a junior secondary homonym of Natrix vulgaris Laurenti, 1768 when transferred to the genus Natrix and thus, according to Articles 57 and 59 of the Code, invalid and does not threaten the usage of Natrix helvetica for the barred grass snake.

Amphibians and reptiles from the late Miocene and early Pliocene of the Ptolemais area (Western Macedonia, Greece)

We herein describe the amphibians and reptiles from the Ptolemais fossil assemblage, originating from 12 nearby localities in northwestern Greece, spanning from the late Miocene (MN 13) to the early Pliocene (MN 15). Amphibians are known exclusively of anurans, with the genera Latonia and Rana being identified, the latter constituting the oldest so far known record of that lineage in Greece. Turtles are represented by the testudinid cf. Testudo, whereas numerous other indeterminate testudinoids are known. Lizards include scincids, lacertids, and at least two anguids. Among them, the material referred to scincids and the anguid Anguis constitute one of only rather few such occurrences described in the fossil record of the Eastern Mediterranean. Snakes are represented by indeterminate “colubrines” and the genus Natrix. The different ages of the Ptolemais fossiliferous localities, along with their close geographic vicinity offer the opportunity to study potential survival/extinction patterns of its amphibians and reptiles across the Mio-Pliocene boundary, a time interval that has been crucial for European herpetofaunas.

Current state of reptiles of Western Podillia.

The results of the research of the current state of reptiles in Western Podillia were presented. Morphometric traits were described; habitat, spread and number of 9 reptile species belonging to 2 lines and 5 families were studied. The regional extinction of Elaphe longissima , which was at the edge of the habitat, was identified. It has been established that the borders of habitats are in the territory of Western Podillia: for Natrix tessellata and Lacerta .viridis – the northern one, for Lacerta vivipara – the southern one.The survey of the found species was made. It was shown that Lacerta agilis appeared to be the most numerous species among reptiles, although its number decreased due to human transformed natural habitats.Such species as Emys orbicularis, Anguis fragilis, Lacerta viridis , Lacerta vivipara , Coronella austriaca and Vipera berus are in a dangerous situation. These species are found sporadically, and there are all reasons to consider them as those which have decreased their number considerably. Natrix natrix and Natrix tessellata are common species. The analysis of reptile occurrence within the region of research has shown that, as to their number, species gravitate to the east and south-east of the region, covering the areas along the left bank of the Dniester River (“Dnistrovskyi canyon”) in Western Podillia Prydnistrovia (administrative territories of Zalishchyky, Bucha, Borshchiv districts of Ternopil region). In Tovtry ridge, they mostly concentrate in the territories of Zbarazh, Pidvolochysk, Husiatyn districts of Ternopil region and Kamianets-Podilsk and Chemerov districts of Khmenlnytskyi region.It is worth mentioning that the area with the highest reptile occurrence coincides with that of reserve “Medobory” and to a lesser degree with the territory of NNP “Podilski Tovtry”. To a great extent the area of reptile concentration coincides with the territory of natural park “Dnistrovskyi canyon”, in particular, closer to the hills of the Dniester River on a tract Beramiany – Ustechko, Zalishchyky – Kasperivtsi (Obizhev and Kasperivskyi reserves) and the outskirts of Dzvenyhorod village, Borshchiv district. In general, the state of reptiles in the region tends to the reduction of the number and diversity of these representatives.

Eastern Montpellier Snake ( Malpolon insignitus fuscus ) Ophiophagy Behavior from Zagros Mountains

Herein, we present three cases of wild Malpolon insignitus preying on Platyceps najadum , Eirenis punctatolineatus , and Natrix tessellata from Iran, in addition one observation from Kurdistan of Iraq. Furthermore, we report two new records of M. insignitus from northwestern Iran.

A Northernmost Record of the Grass Snake ( Natrix natrix ) in the Baikal Lake Region, Siberia

The grass snake ( Natrix natrix ) was observed in Dzelinda thermal spring (the North-Baikal Depression, Buryatia Republic, Siberia, Russia). This locality is situated more than 120 km to the north from the closest known record of the species and, therefore, is the northernmost in the Baikal Lake region. The distribution of N. natrix in the region (Russia and Mongolia) is discussed.

Preliminary results on biological aspects of the grass snake, Natrix natrix in the southern coastal area of the Caspian Sea

Natrix natrix is, together with N. tessellata, the only representative of water snakes found in Iran. The lack of ecological studies on this species in Iran stimulated the current preliminary research on some basic biological traits. From April to July 2008, a total of fifty five snakes were collected from two stations in the southern part of the Caspian Sea coast, Iran: Gomishan Wetland and Sari. Basic morphometrics were compared between sexes and stations and gonadal development was compared between stations and seasons. At the two stations, adult sex ratio was not different from 1:1 and juveniles composed a predominant portion of the sample. Both sexes had unimodal length class size with a peak at 40-45 cm snout-vent length (SVL). Body sizes were unusually small for the species and no SVL sexual dimorphism was detected although males were relatively heavier than females for the same SVL. Snakes of both sexes attained larger size with better body condition at Sari than in Gomishan. Males and females carried more mature gonads in summer. However, in Sari males developed relatively larger testes earlier in the season and both sexes displayed less synchronic reproduction at this station. These results are best explained by local varia- tions in habitat, trophic availability and degree of environmental disturbance.

Reptiles in the diet of a Oncorhynchus mykiss (Osteichthyes: Salmonidae) naturalized population in Piedmont (N Italy)

The authors report on predation by salmonid fish on some reptile species in two tributaries of the Tanaro river in the Alessandria province (NW Italy). The remains of Podarcis muralis, Anguis fragilis and of an undetermined colubrid of the genus Natrix were found in bromatological analyses performed on 117 Oncorhynchus mykiss specimens. Salmonid predation on herpetofauna once again confirms the alimentary opportunism of these fishes; however, predation is an occasional phenomenon and not a threat to the local reptile populations.

Evolution and phylogeny of the genus Natrix (Serpentes: Colubridae)

Some aspects of the natural history of snakes of the colubrid genus Natrix have been well studied. With their extensive European distribution and relative abundance, their ecology, reproduction and behaviour are well known. Yet other facets of their biology remain poorly understood. These include knowledge of Natrix phylogeny, hypotheses explaining the current distribution of the three extant members of the genus, and their evolution and relationships. In this study we used molecular data, the nucleotide sequences of four protein-coding mitochondrial genes (3806 bp total), to provide a well-supported phylogeny for the genus Natrix. With these molecular data, evidence from the fossil record, and knowledge of palaeogeological events, we used two approaches in designing a time scale which we used to date the major events in Natrix speciation and intraspecific variation. Our data strongly support a phylogeny for the genus in which N. maura is basal with N. natrix and N. tessellata being sister species. The calibrated molecular clock suggests that N. maura diverged from the common ancestor of the three species 18–27 mya and that N. natrix and N. tessellata diverged 13–22 mya. Although the ranges of these estimates are large they support an early Miocene to late Oligocene origin for the three species. Intraspecific divergence is estimated to have commenced 5.3, 6.0 and 6.7 mya with evolutionary rates of 1 : 1.25 : 1.35% per million years for N. maura, N. natrix and N. tessellata, respectively. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 127–143.

Reptile Abundance in Temperate-Zone Europe: Effect of Regional Climate and Habitat Factors in Latvia

The role of large-scale factors in influencing reptile abundances in temperate-zone lowland Europe is relatively obscure. Data on relative abundances of reptiles were collected in various regions of Latvia. Multiple regression analysis was used to determine the relationship between reptile abundance and climate and habitat predictors. For lizards, habitat was a more important regional-scale factor than climate, although warmth of summer was important in Lacerta agilis. For snakes, however, climate was a highly significant factor. Natrix natrix in Latvia is common only in areas with mild winter climate at elevations below 50 m a.s.l., while Vipera berus is frequent in upland areas with relatively harsh winters. Potentially, the latter species could be negatively affected by global warming.

Food Niche Partitioning by Water Snakes (GenusNatrix) at a Freshwater Environment in Central Italy

ABSTRACT In central Italy, water snakes of the genus Natrix (N. natrix and N. tessellate) are among the most abundant reptile species. We studied the feeding habits and food niche partitioning by these water snakes at a site located about 25 km north of Rome. The two species partially partitioned the available food sources. N. tessellata showed the highest specificity, feeding particularly on fish and almost exclusively on aquatic prey. N. natrix. on the contrary, preyed especially on amphibians but also on fish and terrestrial vertebrates. The coexistence of these snakes is similar to that reported among North American water snakes of the family Colubridae.

Les Colubridae (Reptilia, Serpentes) du Neogene francais. Le probleme des especes du Miocene de Sansan (Gers)

Thus far, four colubrid snakes from the French Neogene have been named. Three of them, that come from the Miocene of Sansan (Gers), are revised. Scaptophis miocenicus is probably not a miocene fossil, it is considered a nomen dibium. The species sansaniensis LARTET is referred to the genus Natrix and the species pouchetii DE ROCHEBRUNE is transfered to Coluber.

Endocyclic Selection in Natrix

Endocyclic Selection in Natrix

The effect of furosemide on renal function and renin in water snakes

1. Water snakes of the genus Natrix were given a two day regimen of furosemide administration and subjected to a water load. 2. As compared to water loaded controls, the furosemide group showed significant increases in urine flow and osmolality and significant decreases in fractional sodium, potassium, water and distal osmotic reabsorption. Potassium secretion was elevated in the diuretic group. 3. All of these changes occured in the absence of change in GFR or plasma electrolyte or protein concentration. 4. Renal renin content of the furosemide group was significantly elevated over the control group. 5. We concluded that furosemide has both a proximal and distal tubular site of action in Natrix. It is suggested that since no loop of Henle or macula densa is present in this animal furosemide may have a direct effect on juxtaglomerular cells.

Renal tubular transport of calcium and phosphate in snakes: Role of calcitonin

The effect of acute doses of salmon or porcine calcitonin upon serum values and renal excretion of calcium and phosphate was studied in sham-operated or parathyroidectomized water snakes of the genus Natrix. In intact animals, calcitonin appeared to have no significant effect upon the serum values or the renal clearance of phosphate. In the parathyroidectomized animals, calcitonin caused a depression of serum phosphate values and a slight increase in relative renal phosphate clearance ( C PO 4 C In ). Calcium values and glomerular filtration rates were not altered in either group. The effect of calcitonin upon phosphate excretion in snakes seems to be of minimal importance compared to that of parathyroid hormone.

KARYOLOGY OF NORTH AMERICAN NATRICINE SNAKES (FAMILY COLUBRIDAE) OF THE GENERA NATRIX AND REGINA

Four species of the water snake genus Natrix have a distinctly different pattern of chromosomal morphology than found in two species of the related genus Regina. Natrix all have a karyotype with seven pairs of large or medium-sized submetacentric autosomes, three pairs of medium-sized subtelocentric autosomes, and seven pairs of small metacentric autosomes. All have a 2n of 36 with a submetacentric Z and submetacentric or subtelocentric W. The autosomal complement of Regina consists of seven pairs of large to medium-sized submetacentrics, five pairs of medium-sized submetacentrics, and five pairs of small metacentrics. The Z and W are both submetacentric chromosomes. The sex chromosomes are easily distinguished in both genera. The relationships of Natrix and Regina and Old World Natrix are discussed, as well as chromosomal variation in closely related species in the family Colubridae.

The Carolina salt marsh snake: a distinct form of Natrix sipedon

The Carolina salt marsh snake: a distinct form of Natrix sipedon