Firstly...
'ssp.' is an abbreviation for subspecies, 'var.' is the abbreviation for varietas (to give it its international, Latin name). These have nothing to do with hybrids! They both indicate a level in classification below the rank of species -- i.e. a species can be subdivided into 2 or more subspecies. Thus Acacia nuperrima was subdivided into A. nuperrima subsp. nuperrima and A. nuperrima subsp. cassitera (I and many others prefer the abbreviation subsp. to ssp. because it avoids confusion with spp. meaning species plural). As it happens, in the recent Flora of Australia treatment the latter subspecies has been reclassified as A. wickhamii subsp. cassitera, leaving A. nuperrima with no division into subspecies.

Var. is a more traditional classification at below-species level, many taxonomists now preferring to recognize only subspecies while others will use only var. Some use both, in a 2-level classification in which a subsp. is further divided into vars.

As to hybrids in Acacia...
In large areas of Australia natural hybrids seem to be rare or absent among the local Acacia species. There have been very few hybrid names published, as signified by that tell-tale multiplication sign before the specific epithet, unlike, for example, in the eucalypts. But dipping into Flora of Australia again (the 2 Acacia volumes, 2001), I find Acacia x grayana = A. brachybotrya x A. calamifolia, plus mention in notes of several other suspected hybrids in this group of species. If you could find the time to comb right through the 1100+ pages of these volumes you may find yet more.

I would guess that there are strong barriers to inter-specific fertilisation in most Acacias. This is a big subject! Creating garden hybrids is unlikely to be easy.

Thank you Tony for your interesting comments!
phil