Hidden in plain sight: the overlooked establishment of the diamond lizardfish Synodus synodus (Linnaeus, 1758) in the Mediterranean Sea

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Published: Jan 2, 2026
DOI: https://doi.org/10.12681/mms.42764
Keywords:
Non-indigenous species Coastal ecosystems Underwater visual census neo-native Rocky reefs Species establishment
ANTONIO DI FRANCO
Department of Integrative Marine Ecology, Sicily Marine Centre, Stazione Zoologica Anton Dohrn, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy
EMANUELE SOMMA
Department of Integrative Marine Ecology, Sicily Marine Centre, Stazione Zoologica Anton Dohrn, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy & Department of Research Infrastructures for marine biological resources, Ischia Marine Centre, Stazione Zoologica Anton Dohrn, 80077, Ischia, Italy
https://orcid.org/0000-0002-3900-221X
MANFREDI DI LORENZO
Department of Integrative Marine Ecology, Sicily Marine Centre, Stazione Zoologica Anton Dohrn, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy
YANNIS KOUTOULAKIS
Department of Marine Sciences, University of the Aegean, Mytilene 81100, Greece
RYUSEI FURUHASHI
The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan
SYLVAINE GIAKOUMI
Department of Integrative Marine Ecology, Sicily Marine Centre, Stazione Zoologica Anton Dohrn, Lungomare Cristoforo Colombo (complesso Roosevelt), 90149, Palermo, Italy
https://orcid.org/0000-0002-3301-5538
Abstract

The Mediterranean Sea is a global hotspot for marine bioinvasions, with both alien and neo-native species reshaping its biodiversity. Among fishes, the diamond lizardfish Synodus synodus, a subtropical Atlantic taxon, has long been considered rare in the Mediterranean basin, with sporadic and questionable records. Here, we provide the first evidence of established S. synodus populations in the Mediterranean Sea, based on 34 individuals recorded across 18 sites in the Cyclades, Crete (Greece), and Linosa island (Italy). Most individuals were large, suggesting established populations. These findings indicate that S. synodus is more widespread than previously assumed, likely facilitated by ongoing seawater warming and ecological opportunities. Its unnoticed establishment highlights both the ecological relevance of neo-native fishes and the persistent challenges of detecting novel populations, even for conspicuous species, in an era of rapid marine biota restructuring.

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