Thanks for sorting this out.

The species sensu stricto would be the one now generally known as Rubus plicatus Weihe & Nees (certainly not the species shown in the flagged image). But the name "Rubus fruticosus" had been used for different species from the beginning (Linné certainly didn´t have a clear understanding of Rubus taxonomy and species limits). So in all literature I know the name has been discarded (as "nomen ambiguum"). It is still used (not by genuine batologists!) for an amorphous (?) aggregate which might just comprise what is now known as Sectio Rubus or include Sectio Corylifolii or even more sections of Subgenus Rubus.
My first issue was that if one had ID´ed a certain bramble as "Rubus fruticosus agg." and I had ID´ed it as some species that was within Sectio Rubus the ID switched upwards to Genus Rubus, which is illogical.
My second issue was Rubus corylifolius that seems to be seen as species here. A similar case, probably the name was initially intended for the species now known as Rubus pruinosus, but it was used for a lot of related species (sometimes at a lower rank i.e. as some variety or subspecies of R. corylifolius). I admit I have used it in an aggregate sense (as Sectio Corylifolii) here, for species from that section I couldn´t ID down to species level (for various reasons).
And a third issue is the Rubus armeniacus/bifrons problem. If it is decided (using "Flora of North America", no European batologist will accept this) that Rubus bifrons and armeniacus are all the same (and other Discolores except R. ulmifolius are lumped also) why not synonymize R. bifrons and armeniacus, so that all records belong to Rubus bifrons. The vast majority of records from North America (minus a few obvious misidentifications) show the common invasive taxon also known as Himalayan Giant´ orTheodor Reimers´ (name used in Germany but they are one and the same), which is not the species described by Focke and much less Rubus bifrons VEST.

We have lots of species complexes on iNaturalist, but in almost all of these, the constituent species in the complex are children of the complex.
The issue here is that the species got converted to the complex, without any due consideration for observations that were identified to the species (I have no idea how accurately or meaningfully).
Definitely, members of the complex should be its children. Otherwise moving an observation from the complex to the species, or vice versa, is treated as a "wrong ID" instead of a refinement or a withdrawal along the same clade.

As for the purpose of iNaturalist is not to be "an authoritative taxonomic framework", that does not imply that the identifications based on this framework are not being used for crucial scientific and management decisions. With the complex currently regarded as a different "species" to its constituent species, this requires quite a lot of post-downloading work before the data can be used.

Just as I feared: The complex doesn´t exist here! Well, somebody higher up has to decide if this needs to be fixed or not. It might be helpful for both the Rubus fruticosus and the Rubus corylifolius complex as (for various reasons) you´ll often have plants there that cannot be pinned to a (described) species. But it certainly would be a lot of work...

@enkidoo POWO views Rubus fruticosus (ss) as a valid name and considers Rubus plicatus Weihe & Nees to be a synonym http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:735086-1
It has reappeared (as a species) in the iNat taxonomy but is misspelled "fruiticosus".

Do you know where I can get a list of the taxa that are included in the Rubus fruticosus complex/aggregate (& the R. corylifolius complex, too, for that matter). I will try to work my way through and fix up this mess as best I can, grafting the appropriate species onto this R. fruticosus Complex record .

These are the ones I'm aware of because they occur as weeds in Australia
R. anglocandicans A. Newton (not valid in POWO)
R. cissburiensis W.C. Barton & Ridd.
R. echinatus Lindl.
R. erythrops Edees & A. Newton
R. laciniatus Willd., R. leightonii Lees ex Leight.
R. leucostachys Schleich. ex Sm.
R. phaeocarpus W.C.R. Watson
R. polyanthemus Lindeb.
R. riddelsdellii Rilstone
R. rubritinctus W.C.R. Watson
R. ulmifolius Schott (including R. ulmifolius var. ulmifolius and R. ulmifolius var. anoplothyrsus Sudre)
R. vestitus Weihe

But I thought "Batology" was a major field of interest with a huge following. I was under the impression that these guys classified things to to the infinite degree.
However, I dont know anything more than this. Just surprized to discover that things are not as they seem.

No this listing is identical to Genus Rubus, subgenus Rubus section Rubus.
If that is the case the aggregate should be dropped and the subgeneric and section should be added to the taxonomy instead. I assumed that the aggregate was a smaller subset of these that could be easily confused.

From Wiki:

Rubus fruticosus L. is the ambiguous name of a European blackberry species in the genus Rubus in the rose family. The name has been interpreted in several ways:

*The species represented by the type specimen of Rubus fruticosus L., which is also the type specimen of the genus Rubus.[1] This specimen is considered to match the species R. plicatus, in Rubus subgenus Rubus, section Rubus.[2][3] on iNat this would be the species sensum strictum Rubus fruticosus
*Various species consistent with Linnaeus' original description of the species, which was based on a mixture of specimens now considered to match Rubus ulmifolius and R. plicatus a historical issue, not relevant to iNat
*a species aggregate (group of similar species) Rubus fruticosus agg. (a nomen ambiguum) that includes most (or rarely all) of a group called Rubus subgenus Rubus (or less often: Rubus section Rubus [sensu latissimo] [4][5]): on iNat this would be the aggregate or Complex Rubus fruticosus
*in a narrow sense, sometimes separated as the section Glandulosus (alternative name: subsection Hiemales), with about 289 microspecies.[3] In this sense the species aggregate does not include the type of the genus Rubus.not relevant to us?

in a broad sense: (1) (i) sections Glandulosus and Rubus [sensu stricto] (in non-British systems, these two sections are classified together as section Rubus [sensu lato], section Glandulosus being called subsection Hiemales and section Rubus [sensu stricto] being called subsection Rubus) [6][5][7] or (ii) "most of" these sections [8] ; or (2) sections Glandulosus, Rubus [sensu stricto] and Corylifolii.[3] Section Rubus sensu stricto are probably hybrids involving members of section Glandulosus with either R. idaeus or R. allegheniensis.[3] Section Corylifolii (about 24 microspecies) are probably hybrids involving members of section Glandulosus with R. caesius.[3]on iNat this should be the section Rubus Rubus (not in the classification)
*even more broadly, including all the taxa in the subgenus Rubus[5][9]on iNat this should be the subgenus Rubus (not in the classification)

'R fruticosus agg.' is an informal grouping, and - as has been pointed out - means different things to different people. Thus it is neither accurate, nor particularly useful; people just it as wastebasket.

We need to add the subgeneric groupings that batologists use. The complex is large; but even though identifying to species is difficult, it is often easy to identify to section or series. But we don't have section or series level IDs available for Rubus on inat, so here in NZ when I come across something that I can ID to section or series I have had to resort to using a species level ID as a substitute. For example, when I find something from series Corylifolii, I use the name R. tuberculatus (the only species currently listed for series Corylifolii in NZFlora) even if it isn't actually that species; and I put a comment saying something like 'This is not actually R. tuberculatus: I am just using that species here as a standin for series Corylifolii'. It would be much better to be able to add the ID 'Rubus (series Corylifolii)'.

Here is a taxonomic list of the species that are included within 'Rubus fruticosus agg.' in NZ. (There are more sections and series within subgenus rubus in Eurasia and North America, so this system would be incomplete; but it is a demonstration of the kind of subgeneric groupings it would be useful to have access to on inaturalist.)

RUBUS
subgenus Rubus
section Arguti
Rubus argutus
Rubus mollior
Rubus ostryifolius
Rubus x orarius?
section Caesii
Rubus caesius
section Flagellares
Rubus flagellaris
section Rubus
subsection Hiemales (=Glandulosus)
series Corylifolii (usually included under subgenus Rubus)
Rubus conjungens
Rubus tuberculatus
series Discolores
Rubus anglocandicans
Rubus armeniacus
Rubus ulmifolius
series Micantes
Rubus erythrops
series Mucronati
Rubus mucronulatus
series Radulae
Rubus echinatus
series Rhamnifolii
R. amplificatus
Rubus cardiophyllus
Rubus cissburiensis
Rubus cissburiensis x ulmifolius
Rubus nemoralis
Rubus polyanthemus
series Sylvatici
Rubus errabundus
Rubus laciniatus
Rubus leptothyrsos
series Vestiti
Rubus vestitus

((you can edit. Funny stuff happens because of vanilla https://www.markdownguide.org/basic-syntax/ - takes some getting used to))

I couldn't figure out that editing :(

The system laid out above is the standard and would be accepted by almost everybody (the Europeans do merge two of the series, but I forget which).The authority might be difficult, since it is probably a couple of centuries old by this point!

What do you mean by mapping the series to the dictionary ranks?

Fire the monophyleticists!

I can try adding the series myself, but I'll have to get Melissa to show me how...