PDD 99209 (https://scd.landcareresearch.co.nz/Specimen/PDD_99209) has been sequenced. The ITS sequence supports Irma Gamundi's opinion that Ameghiniella is a synonym of Ionomidotis. There is no sequence data available for an Australian specimen identified as Ionomidotis australis. The three A. australis specimens in GenBank represent two different species (one from Chile and Argentina, another from Chile) and the New Zealand specimen PDD 99209 is genetically similar to these. This perhaps reflects the A. australis ssp. australis versus A. australis ssp. valdiviana propopsed by Gamundi, Mycological Research 95: 1131-1136, 1991.
Resolving the taxonomy of these fungi needs a sequence from Australian material - there may be one or more A. australis-like species in Australasia.