“Genus TAWERA n. gen.
(from Tawera, the Maori for "Venus as morning star.")
Type : Venus spissa Deshayes.
Shell oval. Lunule not impressed, bounded by incised line; escutcheon insignificant in type but stronger in ancestral forms; ligament exposed. Sculpture of bevelled, smooth, concentric ridges low and crowded on type but on some species high and spaced; sometimes radials corresponding to the marginal crenulations are developed, especially on lower side of ridges. Hinge-teeth widely divergent; left valve with long, high, posterior cardinal joined to nymph; moderate, bevelled, fairly-deeply but unequally divided median; and long, entire, triangular, widely-diverging anterior one, outer side of which tends to run forward along hinge-margin. Right valve with broadly-grooved posterior cardinal of moderate strength; median triangular, bevelled, rather weakly grooved; anterior one entire, parallel to lunular margin. Pallial sinus short, truncated, ascending. Valve-margins crenate.
Suter, Jukes-Browne and Iredale classed V. spissa in Chamelea Moerch (type V. gallina Linné) and it is with some hesitation that the writer separates Tawera from Chamelea generically. The hinge of Chamelea, however, is much closer to that of Clausinella (type V. fasciata Da Costa) which has a different kind of sculpture.
Tawera differs from Chamelea in having more divergent teeth; in the left valve the posterior cardinal is much stronger, the median is more transverse and always grooved and the anterior is directed further forward.; in the right valve the posterior cardinal is shorter, stronger, more widely grooved and more transverse, the median is better grooved, straighter and vertical, and the anterior cardinal is longer, stronger and directed further forward. The deeply impressed lunule of C. gallina gives a different shape to the shell, but this is not a very important character, for in the European Miocene fossil C. cothurnix Dujardin the lunule is not impressed.
The East Australian Recent V. gallinula Lamk. belongs to Tawera which has, moreover, existed in the Australian area from at least Miocene times, as shown by C. propinqua Tenison-Woods, occurring in the lower and more commonly in the upper beds at Muddy Creek. Chioneryx Iredale, 1924, of which the type is the Australian Erycina cardioides Lamarck, is closely, related to Tawera, and is perhaps a somewhat recent development from that stock. The shape differs from that of Tawera in being more compressed posteriorly, with a slight sinus in the posterio-ventral margin. The hinge-teeth are even more widely divergent than those of Tawera, the right median being considerably extended anteriorly along the hinge-margin. The dominant sculpture of Chioneryx is radial, whereas in Tawera it is concentric.”
(Marwick, 1927: 613)
Tawera is a genus of marine bivalves in the family Veneridae.[1]
As of 2019, the accepted Tawera species (As listed on WoRMS) are as follows.[2]
