Cuisenerita, Symonds, Malcolm Francis & Pacaud, Jean-Michel, 2010

Symonds, Malcolm Francis & Pacaud, Jean-Michel, 2010, New species of Neritidae (Neritimorpha) from the Ypresian and Bartonian of the Paris and Basse-Loire Basins, France, Zootaxa 2606, pp. 55-68: 62-63

publication ID 10.5281/zenodo.197721

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gen. nov.

Genus Cuisenerita  gen. nov.

Type species. Cuisenerita tuberosa  sp. nov.

Derivatio nominis. The only known species within this genus is from the Cuisian of Trosly-Breuil near Cuise-la-Motte and it has many of the characters of a Nerita  and so the name is a free combination of Cuise and Nerita  .

Diagnosis. Capuliform, apex not terminal, radially ribbed, septum well developed, tuberculate, margin dentate, outer lip thickened, lirate.

Remarks. Cuisenerita  is similar in some respects to Velatella Meek, 1873  from the Upper Cretaceous of North America. In describing Neritina  ( Dostia  ?) carditoides, Meek (1873: 499)  commented: “In several respects it agrees with Velates  , and possibly might, without impropriety, be called Velates carditoides  . I suspect, however, that when better specimens can be examined, it will be found typical of an undescribed section, including also the little species N. bellatula  . If so I would propose for the group the name Velatella  .” Article 11.5. 1 of the Code provides that a name proposed conditionally for a taxon before 1961 is not to be excluded on that account alone. Article 11.9. 3.6 provides that a species-group name first published before 1961 in combination with a previously available generic name, but accompanied by a new nominal genus conditionally proposed to contain the new species, is deemed to have been made available in combination with the previously available generic name. The example of Lowe (1843), given in the Code, covers essentially the same situation as that of Meek and Velatella  . Accordingly, although Meek only proposed Velatella  conditionally, Velatella Meek, 1873  is valid. Between his descriptions of N. bellatula  and N. carditoides Meek (1873)  also described Neritina  ( Dostia  ?) patelliformis  . In his description he commented that N. patelliformis  is evidently very close to N. bellatula  and may possibly be a more robust variety of the same. Presumably, therefore, Meek intended to include N. patelliformis  with N. bellatula  and N. carditoides  in the group for which he proposed the name Velatella  . No diagnosis or description is given by Meek for Velatella  but the three species within the group are described in detail, although not figured. White (1883) considered N. carditoides  to be identical with N. bellatula  . Both were figured by him [ N. bellatula: White 1883  : pl. 5, figs 8–9, N. carditoides: White 1883  : pl. 5, fig. 10]. White’s figures of N. bellatula  and N. carditoides  show a dorsal morphology very similar to Cuisenerita  , except that the apex is more strongly involute and curved to one side, and this is supported by Meek’s descriptions. White’s figures do not give an apertural view but Meek (1873: 497–498) described N. bellatula  as having an “inner lip very broad, or shelf like and occupying more than half of the underside, convex and more or less thickened, with the inner margin concave in the middle, and provided with a slight projection on each side, but not properly crenate or dentate”. White also figured a third species, Neritina (Velatella) baptista White, 1878  ( White 1883: pl. 23, figs 16–20), and included an apertural view, which shows a smooth, edentate septum. This accords with Meek’s description but is in contrast to Cuisenerita  , which is strongly dentate on the septum edge and lirate on the outer lip; Cuisenerita  is also characterised by its tuberculate septum, a feature that is lacking in Velatella  .

Cuisenerita  also resembles Gargania Guiscardi, 1857  from the Upper Cretaceous of Italy, which is also radially ribbed and has an apex that is not strongly involute. However the septum is smooth and edentate ( Keen 1960) while in Cuisenerita  it is tuberculate and strongly dentate. Keen treated both Velatella  and Gargania  as subgenera of Pileolus  . As mentioned above, Pileolus  has a culumella and has now been placed in the family Pileolidae  . In Cuisenerita  the internal whorls have been reabsorbed and we have no doubt that Cuisenerita  belongs in Neritidae  not Pileolidae  . The base of Cuisenerita  is similar to that of some species of Nerita  but it differs from that genus in being capuliform with radial ribs. Tomostoma  is also capuliform but the dorsum is smooth, without radial ribs, and the base lacks the tubercles, which are a conspicuous feature of Cuisenerita  .













Symonds, Malcolm Francis & Pacaud, Jean-Michel 2010


Guiscardi 1857