Good morning
I have a question about the French distribution of Agalmatium flavescens.
On this link: http://sysbio.univ-lille1.fr/fiche/flavescens-4 the species seems presented as Mediterranean but if we refer to the INPN map, the species has been observed almost everywhere In France.
Why, in this case, this mention of a Mediterranean species?
It’s a very small dataset (29 obs on the INPN portal, 42 on GBIF) which can amplify biases (for instance 15 of the obs on INPN are from an entomology forum, which may have a more localised userbase or simply reflect human, not insect, population density). We can’t really assume that it’s representative of the real distribution/abundance of the species.
That said, if you look on GBIF, the mostly Mediterranean distribution + outliers becomes a bit more obvious.
One should always check and assess critically the sources of any distribution map.
The INPN maps combine data from several sources, some of which are less reliable (e.g. old literature references with dubious taxonomy, or import of ‘citizen science’ misidentified observations via modern apps…)
For this peculiar insect species, if you look at the sources (the small ‘map’ icon above the map, ‘Voir la carte des observations sur OpenObs’) you will see there are only 29 observations countrywide, and actually very few outside Mediterranean areas (north of a Bordeaux-Lyon line, more or less). Some out-of-range points come from old literature (early XXth c.), whereas a couple of recent observations are in the Paris area - maybe introduced there with cultivated plants? (decorative olive trees are à la mode ;)) And there’s also the issue of climate change, allowing temporary survival (or even range expansion) farther north…
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