Cadmus luctuosus

Wallaga Lake InsectsCadmus luctuosus Cloudy Masked Bee (Hylaeus nubilosus) Moths Rhytiphora neglecta (Flat-faced Longhorn Beetle)

The following photo shows a mating pair of Cadmus luctuosus (no common name), a species of Case-bearing Leaf Beetle, and it is clearly evident just how much difference there is between the two sexes in both size and appearance. In fact, the degree of sexual dimorphism displayed in these two beetles is so extreme that, had I seen them separately, I would have assumed they were individuals representing two different species …. and in the mid 1870’s that’s exactly what happened!

NATURA Far South Coast: Issue 11 ~ February 2024 – by Deb Taylor

The female of this beetle was first described by Chapuis, a French entomologist who made significant contributions to the field of coleopterology (the scientific study of beetles). Much of his work focused on beetles within in the Chrysomelidae family, including the species shown here. Having named the female as maculicollis in 1875, Chapuis then described and named the male beetle as luctuosus in the same year. In other words, because of the sexual dimorphism between the two sexes, Chapius failed to recognise that the specimens he was studying were individuals of the one species. I haven’t been able to ascertain when the male and female beetles were recognised as the same species but I do know that, as far as I can tell and as far as anyone has been able to confirm, this is the first visual documentation of a mating pair.

NATURA Far South Coast: Issue 11 ~ February 2024 – by Deb Taylor

When I uploaded my observation of this beetle to iNaturalist on Feb 16, 2024 it was the first record of the species in not only the Bega Valley Shire but in the whole of NSW. Rather coincidently, 6 days later on Feb 22 Thomas Mesaglio (aka thebeachcomber, and iNaturalist extraordinaire) also uploaded an observation of the beetle – a male that he had photographed at Agnes Banks, 53 km north-west of Sydney – so NSW went from zero observations of the species to 2 in just 6 days. As a final word on Cadmus luctuosus I’d like to acknowledge and thank Boris Büche, an iNaturalist curator living in Berlin, Germany who not only identified the beetles for me but also supplied much of the information relating to Chapius and the taxonomy of Cadmus luctuosus. This is definitely not the first time I’ve benefitted from Boris’s wisdom or been grateful for his assistance.

NATURA Far South Coast: Issue 11 ~ February 2024 – by Deb Taylor

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• Scientific classification
• Kingdom: Animalia
• Phylum: Arthropoda
• Subphylum: Hexapoda
• Class: Insecta
• Informal: Pterygotes
• Order: Coleoptera
• Suborder: Polyphaga
• Superfamily: Chrysomeloidea
• Family: Chrysomelidae
• Subfamily: Cryptocephalinae
• Tribe: Cryptocephalini
• Genus: Cadmus
• Subgenus: Cadmus (Cadmus)
• Species: Cadmus luctuosus

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Wallaga Lake InsectsCadmus luctuosus Cloudy Masked Bee (Hylaeus nubilosus) Moths Rhytiphora neglecta (Flat-faced Longhorn Beetle)

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