# Reproductive Traits and Hatchling Characteristics of the Endemic Sardinian Grass Snake (Natrix helvetica cetti): First Field Data, with Screening for Ophidiomyces ophidiicola

## TL;DR

Researchers studied the reproduction of a rare Sardinian grass snake subspecies, finding unique traits and confirming no presence of a harmful fungus.

## Contribution

First field data on reproduction and health screening for Ophidiomyces ophidiicola in the Sardinian grass snake subspecies.

## Key findings

- Reported the first documented clutch from a wild melanistic female Sardinian grass snake.
- Confirmed the smallest recorded snout-to-vent length for a gravid female N. helvetica.
- Both dam and hatchlings tested negative for Ophidiomyces ophidiicola.

## Abstract

The Sardinian grass snake (Natrix helvetica cetti) is an endangered subspecies endemic to Sardinia, Italy, with a highly fragmented distribution. This study reports the first documented clutch from a wild melanistic female, yielding nine healthy hatchlings. Detailed phenotypic and biometric data were collected and compared to other Natrix natrix complex species, revealing the smallest recorded snout-to-vent length for a gravid female N. helvetica, suggesting unique traits for this subspecies. Both the dam and hatchlings tested negative for Ophidiomyces ophidiicola, the pathogen responsible for ophidiomycosis. These findings address significant gaps in knowledge about the reproductive biology of N. h. cetti, offering helpful insights for the conservation and management of this rare and vulnerable subspecies.

The Sardinian grass snake, Natrix helvetica cetti, is an island-endemic subspecies with a restricted and highly fragmented distribution confined to Sardinia, Italy. Information on its reproductive biology and wild offspring remain scarce in the scientific literature. This present study reports the first recorded data on a clutch of eggs laid by a wild melanistic female N. h. cetti that exhibited lethargy when observed basking, prompting a brief period of health monitoring and screening for the presence of the pathogenic fungus Ophidiomyces ophidiicola (Oo). The clutch yielded nine hatchlings, for which phenotypic data are provided and compared with existing information on the Natrix natrix complex. Both the adult female and its offspring tested negative in the Oo screening. The body size of the adult grass snake, specifically its snout-to-vent length of 48.3 cm, is the smallest ever recorded for a gravid female N. helvetica. This may indicate that maturity is reached at particularly small sizes, a distinctive trait of this intriguing island subspecies, suggesting the need for further investigation.