Revision of Scissurellidae, Anatomidae and Fissurellidae (Gastropoda: Vetigastropoda) from the Plio-Pleistocene of the Philippines Author Helwerda, Renate A. Author Wesselingh, Frank P. text Zootaxa 2014 3838 2 183 194 journal article 10.11646/zootaxa.3838.2.3 b991b3bd-523c-4171-9412-85316ea1ec4b 1175-5326 229062 A3B0A5D4-D989-4804-9501-CE4423F146C9 Zeidora geigeri nov. spec. ( Figure 12 ) Type material. Holotype RGM 961.724. Type locality. Anda 2, Pangasinan, Philippines , Santa Cruz Formation, Pliocene or Early Pleistocene, 16º17′24.8′′ N 119º56′11.8′′ E. Derivatio nominis. Named after Daniel L. Geiger (Santa Barbara Museum of Natural History), authority on Vetigastropoda . Diagnosis. Shell patelliform, elongated; L> 4.54 mm ; H 2.25 mm ; W> 3.50 mm ; apex posterior, low, not extending beyond shell outline; protoconch nucleus with anastomosing ridges; teleoconch sculpture of about 80 primary radial ribs, commarginal ribs forming small nodules on radial ribs; selenizone distinct; posterior septum narrow. Description. Shell small, ovate, whitish, fragile. Spire low, located posteriorly, slightly twisted to right side, nearly reaching but not extending beyond shell outline. Protoconch of 1.1 whorls, located on right side of spire, terminated by a distinct varix. Nucleus sculptured with anastomosing ridges. Teleoconch of 0.9 whorl, elongated, anterior and right side broken. Teleoconch surface sculptured with about 80 fine radial ribs, many commarginal ribs, forming reticulate network with small nodules at intersections. Margins crenulated by radial ribs, crenulations strongest at posteroventral margin. Selenizone moderately narrow, sculptured with curved commarginal ribs, distinct keels on each side. Inner shell surface smooth, shiny. Internal septum located posteriorly, narrow, with slightly thickened rim. Differentiation. There are fourteen Recent species and two fossil species of Zeidora . All of these species differ from Zeidora geigeri nov. spec. because they have a much wider septum and/or a spire that extends beyond the posteroventral margin. Z. tasmanica ( Beddome, 1883 ) from Tasmania, Recent, is most similar in sculpture and shape of the spire, but it has a wider septum. Remarks. The combination of a narrow septum and a spire that does not extend beyond the posteroventral margin in Z. geigeri nov. spec. makes this species unique among the Zeidora species and therefore the description of a new species is justified although it is based on a single, incomplete specimen. The specimen shows enough features for re-identification of additional material found in the future.