It’s hard to track down, and often the exact text where something was synonymized is not indicated. Many of these synonymies are also not well studied as they also happened in the 1800s or early 1900s. Burton’s 1927 revision of Lendenfeld’s 1887 paper seems to be full of erroneous synonymy. And some sponges pictured in Lendenfeld’s paper are obviously synonyms of known sponges today such as Callyspongia azurea - but WoRMS doesn’t list them as such.
Oh boy, now I’ve discovered an even larger mess from the same paper (I expect this to be normal going forward). There is a species I’ve been misidentifying as Callyspongia azurea in E. Australia, which I’ve realized is not that species (due to poor image quality of C. azurea in a different paper), but is actually what would likely today be called Callyspongia elongata / communis / elegans. Problem is, every single one of these are junior homonyms of other Callyspongia species. Also, its original genus (Chalinissa) is now considered a synonym of Axinella, so it wouldn’t even end up in the correct family if I used its original name. So this relatively common E. Australian sponge species literally has no name. I don’t even know what to do with this one.
That is a mess. I think that would make IDing Australian sponges frustrating. I think the best thing to do would either be to identify them at Callyspongia, or at the parent taxon for both Callyspongia and Chalinissa / Axinella and use a tag to keep track of them as @zygy mentioned. Or there’s an even better idea - you could create a time machine and travel back in time to give the scientists some pointers.
I’d recommend making a dropdown-menu observation field with options for each of the species as you interpret them. This allows you do make a parallel informal taxonomy with options that you can filter for on the Explore page, without creating new taxonomy that’s ahead of the literature in iNaturalist’s actual taxonomy system. Basically the same way we treat undescribed species.
To me it definitely sounds like a paper should be published to provide a bit of clarity to the situation… I don’t know if modern taxonomists would ideally want such a paper to involve analysis of specimens and even genetic comparison, but the current situation sounds bad enough that I feel like a more basic attempt at reorganization would be justifiable…
Believe me, if I could time travel I would be giving Lendenfeld something very pointy. This single author has made an absolute mess of sponge taxonomy.
There is actually something of an effort in Australia to work on updating the taxonomy of these troublesome South Australian species, but it’s very preliminary at the moment and I’m not certain of the details yet. We’ll see what happens this year.