Shells belonging to this species are very similar indeed to those of R. auriscalpium from Marzameni, SE. Sicily. However, the new species differs in the larger dimensions of the apex. Moreover, it differs in the longitudinal ribs, which are somewhat less developed and even seem to be completely absent in about one third of the shells. The shells are usually colourless or whitish, and transparent. I saw one specimen which is brownish and transparent, with longitudinal colour lines of a darker brown. Many of the shells of R. rodhensis examined are beach-rolled and in more or less poor condition. For this reason I had to designate the holotype from among the smaller shells. It measures 4.65 mm, has 7.2 whorls and 2 weakly ribbed whorls with 9,5 ribs per whorl. The dimensions of the apex are about d = 0.12 mm. It looks fresh, and is rather well preserved, though slightly damaged.

On the basis of the knowledge available at this moment, I cannot unite R. rodhensis with one of the other species discussed in this paper. It might be conspecific with R. angustior (Monterosato, 1917), which was described from Tripolitania, W. Libya. But Monterosato did not mention details of the apex of his species, which therefore must be considered a nomen dubium until the type specimens, probably in the Monterosato collection in Roma, become available for examination.
R. rodhensis differs from both R. aartseni and R. italiensis in the weak or absent longitudinal ribs, and in the small number of ribbed whorls, which does not exceed three among the specimens examined. It also differs in the greater transparency (as compared with R. italiensis) and in the uniform whitish colour of almost all shells. Fresh shells of R. aartseni always have a colour pattern.

R. rodhensis seems to replace R. auriscalpium in a large part of the eastern Mediterranean. So far, it is only known from Gandoli, 10 km S. of Taranto, S. Italy; Katakolon, 10 km W. of Pirgos, W. Greece; the harbour of Rodhos town, Greece; and Mersa Matruh, 250 km W. of Alexandria, Egypt.