All of the native Convolvulus species were once included in C.erubescens, so the distribution of species within this genus is a little unclear. C.erubescens is only known with certainty from victoria, so any records in NSW would be of interest/significance. I'm not particularly familiar with the species but I believe the inflorescence is 1-4 flowered whereas C.angustissimus has only 1 (rarely 2). :) See https://vicflora.rbg.vic.gov.au/flora/taxon/c99686b0-2cc8-49c4-a7ee-5d9458c2e3c1