Thyasiridae Dall, 1900

Hryniewicz, Krzysztof, Amano, Kazutaka, Jenkins, Robert G. & Kiel, Steffen, 2017, Thyasirid bivalves from Cretaceous and Paleogene cold seeps, Acta Palaeontologica Polonica 62 (4), pp. 705-728 : 709

Family Thyasiridae Dall, 1900 (1895) Genus Conchocele Gabb, 1866

Type species: Thyasira bisecta Conrad, 1849 ; Miocene , Astoria Formation, Astoria, Oregon, USA .

Remarks.—Various species concepts have been applied to the extant members of Conchocele . In some cases smaller and more rounded specimens were referred to as Conchocele bisecta ( Conrad, 1849) , whereas larger and more quadrangular specimens were referred to as Conchocele disjunta ( Gabb, 1866) (e.g., Tegland 1928; Habe 1964; Boss 1967; Bernard 1972). The current approach is to treat both morphospecies as a variation of the same biological species, and to refer to the extant species as C. bisecta due to the rule of priority ( Kamenev et al. 2001; Oliver and Frey 2014). The more extensive discussion of this problem is beyond the scope of this paper, however, we would like to point out that both C. bisecta and C. disjuncta are based on fossil rather than extant material, and each fossil species was erected based on material of different age (Miocene and Pliocene, respectively). Caution should be applied when synonymizing these two fossil species, and when applying these names to extant material. The only name for a North Pacific Conchocele that has been applied to a living species, as far as we are aware of, is Thyasira disjuncta var. ochotica Krishtofovich, 1936 (locality: sea shore). It might be worth to carefully check this “variation” for conchological differences to C. disjuncta ; if there are notable differences, C. “ ochotica ” might be used for extant North Pacific species.