Hi Roger, sorry I don’t have an ID on the host plant. It was a small shrub around 50cm tall, it wasn’t flowering, and you can get an idea of the foliage from the photos. I will be back out that way in a few weeks, so I can take some photos and get the ID of the shrub. It was an understory plant so there is a possibility the true host was the eucalypts above? I also found a single Paropsis augusta on the same shrub.
This species of beetle was recorded by Gunter Maywald in Norhtern NSW. I have a photo. He called it Paropsisterna. I agree. I would first consider the lignea group, ie Paropsisterna interstitialis https://www.inaturalist.org/observations?place_id=any&taxon_id=746034&user_id=martinlagerwey&verifiable=any I'd need a closer look before being confident. P. Faex is possible. Peltoschema is not. It does not occur in Victoria. The host plant looks like Cassinia. Definately NOT the food source.