Kaim, Andrzej, Jenkins, Robert G., Tanabe, Kazushige & Kiel, Steffen, 2014, Mollusks from late Mesozoic seep deposits, chiefly in California, Zootaxa 3861 (5), pp. 401-440: 422

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Diaphana   sp.

( Fig. 9 View FIGURE 9. A – D E –F)

Description. Shell of small size (3.5 mm high and 3.2 mm wide), ovate-subglobose, apical opening narrow but deep, protoconch not preserved. Shell surface flat apart from prosocyrtic growth lines, slightly undulating sigmoidally in the adapical portion. Adapical margin of the outer lip slightly elevated, otherwise aperture not visible.

Material and occurrence: Single shell (GZG.INV. 84994) from West Berryessa (probably Valanginian, Early Cretaceous).

Remarks. Diaphana   sp. is similar to many cephalaspidean taxa belonging to different families or superfamilies (e.g. to aplysiomorphid Akera   or bullid Bullopsis   ) and we classify it as Diaphana   based on its subglobose shell shape, poorly expressed ornamentation, sigmoidal growth lines, and the lack of a groove between the aperture and the preceding whorl typical for Akera ( Vokes 1939)   . Cylichnids are usually densely ornamented and more elongated (see e.g. Sohl 1964). Diaphana   is a cosmopolitan genus, species of which are cosmopolitan and occur in the modern oceans from the intertidal zone down to abyssal depths ( Ohnheiser & Malaquias 2014). Diaphanidae   are considered to represent basal cephalaspideans ( Malaquias et al. 2009). A few other cephalaspidean taxa are known from other Cretaceous seep deposits, including Actaeoninia and Sulcoactaeon   from the Early Cretaceous Koniakauer Schloss site in Czech Republic ( Ascher 1906; Kaim et al. 2013 b), and Sulcoactaeon   sp. from the Late Cretaceous Yasukawa seep site in Hokkaido, Japan (Kaim et al. 2009).