Tawera

Shells of Tawera lagopus, from here.

Belongs within: Venerinae.

Tawera is a genus of venerid bivalves found from the Eocene to the present of Australia and New Zealand. It is distinguished from related genera by the absence of an anterior lateral tooth in the left valve, and the sculpture of fine, rounded concentric ridges. Modern representatives include the New Zealand T. spissa whose shell reaches 24 mm in height, with close concentric ribs over the whole of the disc (Marwick 1927).

Characters (from Marwick 1927): Shell oval. Lunule not impressed, bounded by incised line; escutcheon insignificant in type but stronger in basal forms; ligament exposed. Sculpture of bevelled, smooth, concentric 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 tooth, outer side of which tends to run forward along hinge margin. Right valved with broadly grooved posterior cardinal of moderate strength; median triangular, bevelled, rather moderately grooved; anterior tooth entire, parallel to lunular margin. Pallial sinus short, truncated, ascending. Valve margins crenate.

Tawera Marwick 1927 P61
    |--*T. spissa (Deshayes 1835) P61 (see below for synonymy)
    |--T. assimilis (Hutton 1873) M27 (see below for synonymy)
    |--T. bartrumi Marwick 1927 M27
    |--T. bollonsi Powell 1932 P61
    |--T. carri Marwick 1927 M27
    |--T. errans Marwick 1927 M27
    |--T. gallinula [=Venus gallinula] M27
    |--T. lagopus M54
    |--T. marionae Finlay 1928 P61
    |--T. marshalli Marwick 1927 [=Chione (Ventricoloidea) marshalli Cossmann in Marshall 1917 (n. n.)] M27
    |--T. mawsoni (Hedley 1916) P61
    |--T. propinqua [=Chamelea propinqua] M27
    |--T. rosa Powell 1955 P61
    |--T. subsulcata (Suter 1905) M27 (see below for synonymy)
    `--T. wanganuiensis Marwick 1927 M27

Tawera assimilis (Hutton 1873) M27 [=Chione assimilis M27, Cytherea (Callista) assimilis H86, Macrocallista assimilis M27]

*Tawera spissa (Deshayes 1835) P61 [=Venus spissa P61, Chione (Chamelea) spissa M27, Chioneryx spissa F27; incl. Venus crassa Quoy & Gaimard 1835 M27, Chione gibbosa Hutton 1873 M27, V. mesodesma Quoy & Gaimard 1835 M27, Chione (Chamelea) mesodesma M27]

Tawera subsulcata (Suter 1905) M27 [=Chione subsulcata M27, Chioneryx subsulcata F27, Cytherea (Circomphalus) subsulcata M27]

*Type species of generic name indicated

REFERENCES

[F27] Finlay, H. J. 1927. A further commentary on New Zealand molluscan systematics. Transactions and Proceedings of the New Zealand Institute 57: 320–485.

[H86] Hutton, F. W. 1886. The Mollusca of the Pareora and Oamaru systems of New Zealand. Proceedings of the Linnean Society of New South Wales, series 2, 1 (1): 205–237.

[M54] Macpherson, J. H. 1954. Molluscs (sea shells and snails). In: Willis, J. M. (ed.) The Archipelago of the Recherche pp. 55–63. Australian Geographical Society: Melbourne.

[M27] Marwick, J. 1927. The Veneridae of New Zealand. Transactions and Proceedings of the New Zealand Institute 57: 567–636.

[P61] Powell, A. W. B. 1961. Shells of New Zealand: An illustrated handbook 4^th ed. Whitcombe and Tombs Limited: Christchurch.

Last updated: 24 October 2021.