The Fifth Labour of Heracles: Cleaning the Linnean stable of names for grass snakes (Natrix astreptophora, N. helvetica, N. natrix sensu stricto)

Citizen Science, taxonomy and grass snakes: iNaturalist helps to clarify variation of coloration and pattern in Natrix natrix subspecies

“…This only recently recognized subspecies (Fritz and Schmidtler 2020;Asztalos et al 2021a, b) resembles in coloration and pattern N. n. natrix, but the body coloration tends to be lighter. In addition, the crescents are more frequently pale orange colored than in the nominotypical subspecies.…”

“…In addition, partially or completely melanistic individuals and two rare coloration variations, the 'picturata morphotype' and the spotted 'schweizeri morphotype,' were recorded and plotted. Melanistic grass snakes and the 'picturata morphotype' are known both from N. natrix and N. helvetica (Fritz and Schmidtler 2020). The 'picturata morphotype' was originally described by Jan (1864) as Tropidonotus natrix var.…”

Natrix natrix after dark: citizen science sheds light on the common grass snake’s nightlife

“…Our study concerns the nominate species ( Natrix natrix sensu stricto according to current classifications) which, depending on the subspecies, can reach a total length of 150 to 200 cm and feeds on amphibians, fish and small mammals or birds ( Fuhn & Vancea, 1961 ; Kindler et al, 2013 ; Speybroeck et al, 2016 ; Asztalos et al, 2021 ). Throughout its range, from the Rhine region in Germany eastward to Lake Baikal, including also Fennoscandia, the Balkan Peninsula and some parts of the Middle East ( Kindler et al, 2017 ; Fritz & Schmidtler, 2020 ; Asztalos et al, 2021 ), the grass snake is mostly associated with aquatic habitats.…”

“…Although N. natrix is considered both diurnal and nocturnal ( Speybroeck et al, 2016 ), there is very limited empirical data available to support this. While some publications mention nocturnality of N. natrix sensu lato , one of them concerns the Sardinian grass snake ( Capula, Rugiero & Luiselli, 1994 ), which is now regarded as a different species ( Schultze et al, 2020 ; Fritz & Schmidtler, 2020 ), while others provide little to no evidence for this phenomenon ( Agrimi & Luiselli, 1994 ; Mertens, 1994 ; Speybroeck et al, 2016 ). Here we aimed to document the patterns of crepuscular and nocturnal activity in N. natrix across its distribution range using citizen science, as well as our own data, in order to understand (i) how common it is, (ii) whether there are any geographical variations, (iii) whether there is any significant association between environmental variables (temperature, and moon presence and moonlight) and the activity patterns, and (iv) whether there is any significant difference regarding temperatures between the phenotype (color morph) in crepuscular and nocturnal snakes.…”

The Endangered Sardinian Grass Snake: Distribution Update, Bioclimatic Niche Modelling, Dorsal Pattern Characterisation, and Literature Review

“…The Sardinian grass snakes and the Corsican grass snakes could be considered synonyms since they have been demonstrated to be genetically undifferentiated [ 22 ]. However, pending studies include a larger sample from both islands, and considering the high threat status of the Sardinian populations, it has been suggested to tentatively keep two separate subspecies - N. h. cetti and N. h. corsa -([ 22 , 23 ]; see Section 3.1.1 ). For this reason, in the present work, the taxon name N. h. cetti is applied in reference to the Sardinian populations only.…”