Marbled Fern Musotima nitidalis

Originally given the vernacular name Golden-brown Fern Moth.

This is an adventive species from Australia and New Zealand which was first found in the UK in Dorset in 2009 and in Norfolk in 2020.

By 2023 quite a few people had caught this species at various sites around the county, so it was inevitable that I would find one before too long. My first two were in 2024. This one was my second - a slightly worn but otherwise typically-coloured individual.

Marbled Fern Musotima nitidalis (last photo showing it from underneath), North Elmham (Norfolk, UK), 1st October 2024

This one was my first and it didn't look like I was expecting. Every photo of the species that I had seen showed dark brown at the centre of the forewing between the main cross-lines and contastingly pale orangey-brown at the base of the wing and towards the apex of the wing. On mine the base and tip of the wing was the same dark brown as the centre. There were orange markings along the leading edge and along the crosslines but very little at the base and tips of the wing. I couldn't find any similar photos taken in the UK or Europe. Eventually I found a some photos taken in Australia and New Zealand and a proportion of the New Zealand ones (and one taken in Australia) were like mine. So far I haven't worked out if this is purely normal variation, perhaps more common in NZ population than elsewhere, or if there's something else going on (like people selecting photos of the more colourful form, for example). Eventually I did find photos of one or two others that were similar in the UK, plus a handful that were intermediate, but it still seems that for some reason this form is more unusual here than it is in their native range.

Marbled Fern Musotima nitidalis (last photo showing it from underneath), North Elmham (Norfolk, UK), 8th September 2024

This one is more intermediate in appearance.

Marbled Fern Musotima nitidalis, North Elmham (Norfolk, UK), 24th October 2024

Marbled Fern Musotima nitidalis, North Elmham (Norfolk, UK), 28th October 2024