Glimmer Of Hope For Critically Endangered Species

A new study has formed a sexual maturity data set for the critically endangered Manapany day gecko phelsuma inexpectata. This has never been done before as no precedent readings have ever been made in such a huge number.

The gecko is endemic to the isolated Rèunion Island, near Mauritius and is falling in numbers due to urbanisation and agriculture expansion. It has had a 45% decrease of distribution between 2008-2022.

Réunion Island Waterfall

Between the sexes, there is clarity:

"males are described as larger and more colourful than females (Sanchez

et al., 2009), but no biometric data are available and the measurements of only four individuals have been previously published (see Mertens, 1966; Vinson & Vinson, 1969)."

Determining Sexual Maturity

It is determined through this study that different structural characteristics, such as age and sex, may be able to quash past miscalculations of sexual maturity age and body size numbers.

Snout-vent length and tail length were also measured to capture the sexual maturity of an individual. Males would be mature at 42.1mm SVL and females at 47mm SVL. Previously, studies were showing much smaller and vague SVL numbers which would delay breeding proceedings.

Seasonal Changes

The time of year is a prevalent factor of this study. Gravid Females were found to be holding eggs as early as May - July. Their usual production period would be August to November.

Breeding programmes, from a conservational stand-point, will be able to identify key "distinctions between sexes and between immature and mature geckos".

Final Thoughts

There is still time to act based on the findings of this study. Knowing when these geckos are able to reproduce, as early in their life stage as possible, may be the difference in extinction and survival of the species.

Manapany day gecko

Bibliography

Mickaël Sanchez, Alicia Bonanno, Margot Caubit & Johanna Clémencet (2025) Size at sexual maturity, sexual size dimorphism and new

data on the breeding period of the threatened Phelsuma

inexpectata. Available from: https://www.thebhs.org/publications/the-herpetological-journal/volume-35-number-2-april-2025[Accessed 18 November 2025].

Mickaël Sanchez, Alicia Bonanno, Margot Caubit & Johanna Clémencet (2025) Current distribution of Phelsuma inexpectata, a threatened Réunion Island endemic gecko Available from: https://www.cambridge.org/core/journals/oryx/article/current-distribution-of-phelsuma-inexpectata-a-threatened-reunion-island-endemic-gecko/A57D44AFDB40357C3496A00E938100F0[Accessed 18 November 2025].

Mertens, R. (1966). Die nichtmadagassichen Arten

und Unterarten der Geckonengattung Phelsuma.

Senckenbergiana Biologica 47, 85–110.

Vinson, J. & Vinson, J.-M. (1969). The saurian fauna of the

Mascarene Islands. 1. A revision of the fauna. Mauritius

Institute Bulletin 6, 203–320.

Sanchez, M., Probst, J.-M. & Deso, G. (2009). Phelsuma

inexpectata Mertens, 1966 (Squamata : Gekkonidae) sur

l’île de La Réunion : écologie, répartition et menaces.

Bulletin de la Société Herpétologique de France 132, 43–69.