Avonia Thomas, 1914

Carniti, Alessandro P., Porta, Giovanna Della, Banks, Vanessa J., Stephenson, Michael H. & Angiolini, Lucia, 2022, Brachiopod fauna from uppermost Visean (Mississippian) mud mounds in Derbyshire, UK, Acta Palaeontologica Polonica 67 (4), pp. 865-915 : 882

Genus Avonia Thomas, 1914

Type species: Productus youngianus Davidson, 1860a , from the Visean of Scotland .

Remarks.— Avonia differs from Quasiavonia Brunton, 1966 , in having narrow faint costae covering all valve surface except the umbonal region, instead of the broad, low ones restricted to the anterior portion of both valves which characterise the latter, and in having weaker and more regular lamellae. Moreover, Avonia is smaller in size, more elongated in outline and has a shallower corpus cavity. Avonia differs from Breileenia Brunton in Brunton and Lazarev, 1997, of the Marginiferinae Stehli, 1954 , in being smaller, not geniculated, and in having fainter, narrower costae, but stronger lamellae. Avonia differs from Institifera Muir-Wood and Cooper, 1960 , in having a markedly shallower corpus cavity, more elongated outline, less prominent delayed costae and in lacking a gutter anteriorly.