Liya A. Idrisova and Ildar Z. Khairutdinov // Russian Journal of Herpetology Vol. 25, No. 4, 2018, pp. 283 – 292

Reptile phenotype is influenced by both external (environment) and internal (genotype) factors. However, the relation between these factors are not clear today. This research analyzes the influence of temperature during egg incubation on morphological characteristics of the grass snake. We found out that extreme high temperature resulted in shorter incubation length and smaller hatchlings. Coloration was also affected by thermal regime: there were more bright orange and yellow tones observed in the temporal spots, neck, labial scales and iris of hatchlings from high temperature regimes. Hatchlings which were incubated at extreme high temperatures were characterized by the largest spectrum and the highest frequency of deviations in pholidosis and malformations; as well some of them failed to hatch. The appearance of effect is influenced by exposure duration: hatchlings incubated at fluctuating temperatures demonstrated intermediate characteristics.

Frederic Griesbaum and Korbinian Pacher //  North-Western Journal of Zoology, 2024, 20(1) : 90-93

We report three recent observations of striped individuals of the grass snake (Natrix natrix) from Berlin, Germany. Such animals have been described from the region earlier, although this color morph is typical for south-eastern European populations. All three observations were made in anthropogenic habitats, which have been highly frequented by visitors for decades. Based on our anecdotal findings and recent publications on the morpho-geography of the species, we hypothesize that introduced individuals might play a more significant role in the polymorphism of grass snakes than previously thought. Finally, we overview all published observations of striped grass snakes in Central Europe and discuss the implications of potentially introduced non-native genotypes. 

Моднов А.С. // Вестник ТГУ, т.14, вып.2, 2009. С. 394 - 402

Представлены сведения о морфометрических показателях и признаках фолидозиса обыкновенного ужа (Natrix natrix) из девяти мест Цнинского лесного массива (Тамбовская область). Проводится сравнение полученных данных с результатами других исследователей.

Гордеев Д.А. // Известия Самарского научного центра Российской академии наук. 2012. Т. 14, № 1. С. 150 - 153

В настоящей работе обсуждаются региональные особенности биологии, экологии и морфологии ужа обыкновенного, показано распространение вида на территории Волгоградской области, дана характеристика подвидов на основе метрических и меристических признаков. Проанализированы основные показатели, применяемые в систематике вида. 

Моднов А.С. // Вестник ТГУ, т.15, вып.2, 2010. С. 660 - 664

На основании собственных материалов, собранных в 2005–2009 гг., дается экологическая характеристика обыкновенного ужа (Natrix natrix) Цнинского лесного массива (Тамбовская область). Приводятся сведения о предпочитаемых биотопах, численности, сезонной и суточной активности, питанию змей. Эти материалы сравниваются с данными из цитированной литературы.

Leszek Satora // Veterinary and human toxicology 2004 Dec; 46(6): 334.

The non life-threatening results of a bite from a grass snake in a 17-y-old patient are described, their significance evaluated, and the hazard of such bites discussed.

Uwe Fritz, Josef Schmidtler // Vertebrate Zoology 70(4) 2020: 621-665

We scrutinize scientific names erected for or referred to Natrix astreptophora (Seoane, 1884), Natrix helvetica (Lacepède, 1789), and Natrix natrix (Linnaeus, 1758). As far as possible, we provide synonymies for the individual subspecies of each species, identify each name with one of the mtDNA lineages or nuclear genomic clusters within these taxa, and clarify the whereabouts of type material. In addition, we feature homonyms and names erroneously identified with grass snakes. For Natrix astreptophora (Seoane, 1884), we recognize a second subspecies from North Africa under the name Natrix astreptophora algerica (Hecht, 1930). The nominotypical subspecies occurs in the European part of the distribution range (Iberian Peninsula, adjacent France). Within Natrix helvetica (Lacepède, 1789), we recognize four subspecies. The nominotypical subspecies occurs in the northern distribution range, Natrix helvetica sicula (Cuvier, 1829) in Sicily, mainland Italy and adjacent regions, Natrix helvetica cetti Gené, 1839 on Sardinia, and Natrix helvetica corsa (Hecht, 1930) on Corsica. However, the validity of the latter subspecies is questionable. For Natrix Cetti Gené, 1839, we designate a lectotype from Sardinia to stabilize current usage of this name. Furthermore, we give Coluber siculus Cuvier, 1829 and Tropidonotus natrix var. astreptophorus Seoane, 1884 precedence over four previously overlooked senior synonyms that we qualify as nomina oblita according to the requirements of the International Code of Zoological Nomenclature. Coluber bipedalis Bechstein, 1802 and Vipera vissena Rafinesque, 1814 are nomina oblita for Coluber siculus Cuvier, 1829. Coluber distinctus Gravenhorst, 1807 and Tropidonotus sparsus Schreiber, 1875 are nomina oblita for Tropidonotus natrix var. astreptophorus Seoane, 1884. For Natrix natrix (Linnaeus, 1758) we recognize tentatively five subspecies, some of which hybridize broadly. The nominotypical subspecies matches the ‘yellow mtDNA lineage’ and the ‘yellow microsatellite cluster’ and lives in Scandinavia and Central Europe. For Natrix vulgaris Laurenti, 1768, we designate a neotype and resurrect this name for the previously characterized ‘red mtDNA lineage’ of Natrix natrix that also corresponds to a distinct nuclear genomic cluster (Natrix natrix vulgaris Laurenti, 1768). Pure populations of this subspecies are restricted to southern and southeastern Central Europe. The ‘green mtDNA lineage’ of Natrix natrix, also distinct with respect to nuclear genomic markers, corresponds to Natrix natrix scutata (Pallas, 1771). This subspecies occurs in most of the eastern distribution range. Natrix natrix persa (Pallas, 1814) is characterized by another mtDNA lineage endemic to the Transcaucasus und northern Iran. We restrict this subspecies to populations in these regions, while the taxonomic status of grass snakes from the Balkans and Asia Minor, previously also assigned to Natrix natrix persa, demands further research. Finally, we tentatively recognize Natrix natrix syriaca (Hecht, 1930) as valid. This subspecies is characterized by yet another mtDNA lineage endemic to southeastern Turkey. Based on genetic evidence, the following subspecies should not be recognized: Natrix natrix fusca Cattaneo, 1990, Natrix natrix gotlandica Nilson & Andrén, 1981, and Natrix natrix schweizeri Müller, 1932. Some other names can be unambiguously identified with distinct mtDNA lineages and could represent distinct taxa. However, without additional nuclear genomic evidence, we refrain from potentially premature taxonomic decisions. 

Uwe Fritz, Flora Ihlow // Vertebrate Zoology 72, 2022, 533–549

We used a dataset of georeferenced photos of 5,751 grass snakes from iNaturalist to evaluate subspecific variation of Natrix natrix in coloration and pattern. Our results provide evidence that all four genetically delineated subspecies differ morphologically, although unstriped individuals of N. n. vulgaris are difficult to tell apart from the nominotypical subspecies. The iNaturalist dataset shows that the frequency of dark body coloration increases from south to north and from west to east. This trend is both concordant with taxonomic variation (the easternmost subspecies, N. n. scutata, being the darkest taxon) and variation within the same subspecies (in N. n. natrix and N. n. scutata more northern populations harbor more dark or melanistic individuals than more southern populations). Although available characters were limited to coloration and pattern traits, our study suggests that photo material from iNaturalist and similar platforms can be a valuable data source for studies on morphological variation. However, investigations using such databases can only supplement, but not replace, studies using museum material because only then measureable, meristic and genetic characters will be accessible.

Nikolaj L. Orlow und Boris S. Tunijew // Handbuch der Reptilien und Amphibien Europas. Band 3/IIA: Schlangen II Wiebelsheim: Aula-Verlag. (pp. 505–512). 

Marika Asztalos, Dinçer Ayaz, Yusuf Bayrakcı, Murat Afsar, Cemal Varol Tok, Carolin Kindler, Daniel Jablonski, Uwe Fritz // Vertebrate Zoology 71, 2021, 813–834

Using two mitochondrial DNA fragments and 13 microsatellite loci, we examined the phylogeographic structure and taxonomy of two codistributed snake species (Natrix natrix, N. tessellata) in their eastern distribution area, with a focus on Turkey. We found evidence for frequent interspecific hybridization, previously thought to be extremely rare, and for backcrosses. This underscores that closely related sympatric species should be studied together because otherwise the signal of hybridization will be missed. Furthermore, the phylogeographic patterns of the two species show many parallels, suggestive of a shared biogeographic history. In general, the phylogeographies follow the paradigm of southern richness to northern purity, but the dice snake has some additional lineages in the south and east in regions where grass snakes do not occur. For both species, the Balkan Peninsula and the Caucasus region served as glacial refugia, with several mitochondrial lineages occurring in close proximity. Our results show that the mitochondrial divergences in both species match nuclear genomic differentiation. Yet, in the former glacial refugia of grass snakes there are fewer nuclear clusters than mitochondrial lineages, suggesting that Holocene range expansions transformed the glacial hotspots in melting pots where only the mitochondrial lineages persisted, bearing witness of former diversity. On the other hand, the deep mitochondrial divergences in N. tessellata across its entire range indicate that more than one species could be involved, even though lacking microsatellite data outside of Turkey prevent firm conclusions. On the contrary, our microsatellite and mitochondrial data corroborate that N. megalocephala is invalid and not differentiated from sympatric populations of N. natrix. For Cypriot grass snakes, our analyses yielded conflicting results. A critical assessment of the available evidence suggests that N. natrix is a genetically impoverished recent invader on Cyprus and taxonomically not distinct from a subspecies also occurring in western Anatolia and the southern Balkans. Based on combined mitochondrial and nuclear genomic evidence we propose that for grass snakes the following subspecies should be recognized in our study region: (1) Natrix natrix vulgaris Laurenti, 1768, southeastern Central Europe and northern Balkans; (2) Natrix natrix moreotica (Bedriaga, 1882), southern Balkans, western Anatolia, and Cyprus; and (3) Natrix natrix scutata (Pallas, 1771), eastern Anatolia, Caucasus region, Iran, northeastern distribution range (from eastern Poland and Finland to Kazakhstan and the Lake Baikal region). Thus, Natrix natrix cypriaca (Hecht, 1930) becomes a junior synonym of N. n. moreotica and Natrix natrix persa (Pallas, 1814) becomes a junior synonym of N. n. scutata. Due to insufficient material, we could not resolve the status of Natrix natrix syriaca (Hecht, 1930) from the Gulf of İskenderun, southeastern Turkey. 

Felix Pokrant, Carolin Kindler, Martin Ivanov, Marc Cheylan, Philippe Geniez, Wolfgang Böhme, Uwe Fritz // Biological Journal of the Linnean Society, Volume 118, Issue 4, August 2016, Pages 873–888

The grass snake (Natrix natrix) is Europe’s most widely distributed and, in many regions, most common snake species, with many morphologically defined subspecies. Yet, the taxonomy of grass snakes is relatively little studied and recent work has shown major conflicts between morphologically defined subspecies and phylogeographical differentiation. Using external morphology, osteological characters, and information from 13 microsatellite loci and two mitochondrial markers, we examine differentiation of the subspecies N. n. astreptophora from the North African Maghreb region, the Iberian Peninsula and neighbouring France. According to previous studies, N. n. astreptophora corresponds to a deeply divergent mitochondrial clade and constitutes the sister taxon of all remaining grass snakes. In the French Pyrenees region, there is a contact zone of N. n. astreptophora with another subspecies, N. n. helvetica. Our analyses of microsatellites and mitochondrial DNA reveal that the distribution ranges of the two taxa abut there, but both hybridize only exceptionally. Even though many morphological characters are highly variable and homoplastic in grass snakes, N. n. astreptophora differs consistently from all other grass snakes by its reddish iris coloration and in having significantly fewer ventral scales and another skull morphology. Considering further the virtual absence of gene flow between N. n. astreptophora and N. n. helvetica, and acknowledging the morphological distinctiveness of N. n. astreptophora and its sister group relationship to all remaining subspecies of grass snakes, we conclude that Natrix astreptophora (Seoane, 1884) should be recognized as a distinct species. Further research is needed to explore whether N. astreptophora is polytypic because a single sample of N. astreptophora from Tunisia turned out to be genetically highly distinct from its European conspecifics.

Carolin Kindler, Maxime Chevre, Sylvain Ursenbacher, Wolfgang Böhme, Axel Hille, Daniel Jablonski, Melita Vamberger1 & Uwe Fritz // Scientific Reports, 7 (1), 7378 - August 2017

Recent studies found major conficts between traditional taxonomy and genetic diferentiation of grass snakes and identifed previously unknown secondary contact zones. Until now, little is known about gene fow across these contact zones. Using two mitochondrial markers and 13 microsatellite loci, we examined two contact zones. One, largely corresponding to the Rhine region, involves the western subspecies Natrix natrix helvetica and the eastern subspecies N. n. natrix, whereas in the other, more easterly, contact zone two lineages meet that are currently identifed with N. n. natrix and N. n. persa. This second contact zone runs across Central Europe to the southern Balkans. Our analyses reveal that the western contact zone is narrow, with parapatrically distributed mitochondrial lineages and limited, largely unidirectional nuclear gene fow. In contrast, the eastern contact zone is very wide, with massive nuclear admixture and broadly overlapping mitochondrial lineages. In combination with additional lines of evidence (morphology, phylogeny, divergence times), we conclude that these diferences refect diferent stages in the speciation process and that Natrix helvetica should be regarded as a distinct species. We suggest a nomenclatural framework for presently recognized grass snake taxa and highlight the need for reconciling the conficts between genetics and taxonomy.

Mertens R // Abh. der Senckenberg. Naturforsch. Gesellschaft. - Frankfurt a. M.: Verlag Kramer, 1947. - Bd. 476. - 38 S.

Аль-Завахра Х.К. // Чтения памяти Виктора Алексеевича Попова. Казань: Казанский ГУ, 1997. С. 20 - 24

Идрисова Л. А., Хайрутдинов И. З. // Изв. Сарат. ун-та. Нов. сер. Сер. Химия. Биология. Экология. 2016. Т. 16, вып. 2. С. 190 - 197

В статье рассматривается флуктуирующая асимметрия фолидоза обыкновенного ужа в четырех районах Республики Татарстан. Проведен статистический анализ асимметричных признаков, вычислены интегральные оценки величины флуктуирующей асимметрии. Асимметрия фолидоза отмечена у 32% всех особей. Чаще всего наблюдается асимметрия височных, заглазничных и нижнегубных щитков – признаков, характеризующихся наибольшим разнообразием. Статистически значимых половых, возрастных различий и различий между выборками из разных районов в значениях показателей флуктуирующей асимметрии (ФА) не выявлено.