Is this where there were seeds? I don't see the seed heads in the photo. To quote VicFlora "The taxa in this genus can be difficult to distinguish, particularly in the absence of mature fruits. Identification may be further complicated by the occurrence of hybrids which can display virtually all the possible character combinations."
Barb, as far as I can see, those other listed Acaena including hybrids seem to have a tufted growth / rosette and not this prostrate creeping growth habit. I shall have a better look - I came across it when I crawled along the edge of the water course (now without water) under the bushes to remove 100s of privets and ivy...
Waltruad is spot on, the comment in Vicflora refers instead to the tufted species e.g. A.echinata. Although even this group is identifiable from photographs assuming the leaf underside is photographed