Remarks. — Based on their type species, the differences between Merica and Sydaphera Iredale, 1929, are, respectively: shell form: biconical vs. fusiform; whorls: rounded vs shouldered, with whorl sides parallel to axis; shoulders: not marked vs. rounded but well marked; columella: bent abaxially vs. less so; sculpture: axial and spiral equally strong, vs. mainly axial. Several species from both genera can be clearly distinguished, but study of a larger sample of shells currently classified in Merica and in Sydaphera seems to indicate that there is a gradual change in shell characters, without a clear delimitation between these two groups. In general, species of Merica have a rather rounded outline, with no or very weak shoulders, and shells of Sydaphera species are elongate, shouldered. But in both genera, species have been classified that are tending towards the form of the other genus, and the increasing number of shells and species becoming available for study has slowly filled the gaps between cited differences.
Also, a great variability is seen within the species of both genera. The identification problems in Merica are long known (Verhecken, 1986: 38; Petit & Harasewych, 2000: 142), and Sydaphera seems to have been used for several species not easily placed elsewhere. Petit & Harasewych (1986) while describing C. boucheti and C. aqualica, preferred a conservative stand and used the genus Cancellaria. Merica lussii Petit & Harasewych, 2000, although most probably correctly placed, has the general shell form tending to Sydaphera. Now that more material from the western Pacific is at hand (also colln REP, AV) it becomes clear that shells quite different in general form can be linked to each other in an almost continuous line, starting from the axially compressed Merica aqualica to the elongate Sydaphera gigantea.
It also shows that, within some species now classified under Sydaphera, juvenile shells can be almost indistinguishable from Merica species.
My conclusion is that it is no longer possible to maintain a clear separation between Merica and Sydaphera. This conclusion, based on shell characters, now seems to be backed up by molecular results (Modica et al., in press) uniting species of both genera in one clade. If this conclusion can be confirmed, then the senior name Merica would be the valid name for the genus. Sydaphera and Merica s.s. are here considered subgenera of the genus Merica. This partly solves the classification problem, but evidently intermediate forms will remain difficult to place.
The Sydaphera material here studied consists mainly of rather large to large shells, consequently their protoconch is often damaged to a degree that even the protoconch type can¬not be recognised.