Shell of 5.25-5.50 whorls, length 2.26-2.80 mm. Protoconch of 1.25 (1-1.25) whorls, with spiral beaded cords and 10 beads per 100 µm. Diameter of nucleus 0.13 (0.11-0.14) mm, first half whorl 0.25 (0.23-0.27) mm. Teleoconch whorls slightly convex, with 12 (12-13) axial ribs on first whorl, 12 (12-13) on penultimate whorl, with 2 spiral ribs on first whorl, 3 on penultimate whorl, and 3 basal spiral keels on last whorl. Axial rib/interspace ratio 1.5, spiral ribs/ interspace ratio 1. Aperture D-shaped, with outer lip duplicated; labial varix pronounced. Shell colour white (all available material empty shells). Axial ribs not extending onto base. Relative height (L/N) 0.48 (0.43-0.53); slenderness (L/D ) 2.60 (2.50-2.74). Penultimate whorl height/width ratio (W )/D ) 0.60 (0.54-0.67); aperture/ height ratio (M/L) 0.23 (0.21-0.25). Teleoconch microsculpture finely cancellated.

As for M. cheilostoma, no wet material was available for this species. Unlike the former species, however, some material examined is freshly collected. The most remarkable peculiarity of the shells of M. cancellata is the strength of the third spiral rib on the earlier teleoconch whorls. This sculptural element may range from being barely detectable to being as pronounced as the other two.
Of the New Zealand species, M. cancellata is most similar in shell characters to M. maoriana and M. plaga Finlay, 1926. However, based on the examination of several lots, both New Zealand species have markedly larger shells. M cancellata appears to have been commonly misidentified as M. cheilostoma in Tasmania and Victoria. In addition, its general similarity to Hutton's Rissoa plicata (= M. maoriana), resulted in the erroneous synonymies between M cheilostoma and that taxon.
Merelina cancellata differs from most of the Australian taxa in having a cancellated microsculpture. This feature is only shared with M. cheilostoma and M. norfolkensis n. sp., from which M. cancellata is clearly distinct in its size and more obvious general sculptural elements.

From Victoria (Western Port) to South Tasmania (South Bruny Is.) where it occurs in samples from the inner continental shelf, subtidal and shore debris. Microabitat unknown.