Nucinella gigantea Amano, Jenkins, and Hikida, 2007
|
publication ID |
https://doi.org/ 10.4202/app.2008.0310 |
|
persistent identifier |
https://treatment.plazi.org/id/497287A1-F62C-7B27-9C6E-F8F7FDE2F38F |
|
treatment provided by |
Felipe |
|
scientific name |
Nucinella gigantea Amano, Jenkins, and Hikida, 2007 |
| status |
|
Nucinella gigantea Amano, Jenkins, and Hikida, 2007 View in CoL
Fig. 3 View Fig .
2007 Nucinella gigantea sp. nov.; Amano et al. 2007: 85, figs. 2–7.
Material.— Twelve specimens from the Kanajirisawa seep site in Obira Town .
Discussion.—The specimens from Kanajirisawa are similar in size (18 mm in length) and outline to the type material of Nucinella gigantea . In the right valve, a central tooth thin and oblique anteriorly, and three small teeth are recognized before the central tooth ( Fig. 3C View Fig ). One posterior tooth can be recognized behind the central tooth. In the left valve, three anterior teeth are present, among which the anterior−most tooth is shaped like a reverse “S” and is parallel to the hinge base ( Fig. 3D View Fig ). The two central teeth are large but thin, and connected to a small posterior tooth. A narrow flat area is also present below the dentition. The number of teeth in the specimens found at the Kanajirisawa site (five in the right valve and six in the left valve) is slightly lower than in the type specimens (six in the right valve and nine in the left valve) of Nucinella gigantea . However, the large size, nuculid shell shape and one or two large central teeth allow us to safely identify the specimens as N. gigantea .
One specimen has a circular drill hole (outer diameter 1.5 mm; inner diameter 1.4 mm) and a healed shell injury that is commarginal, short, and straight, and resulted in a ridgelike trace in the remainder of the shell, indicating that this injury affected not only the shell but also the shell−forming mantle margin ( Fig. 3A View Fig ). The shape of drill hole is similar to that made by naticids, but naticids have so far not been found at this locality (own observations and Andrzej Kaim, personal communication, 2007). Thus the predator that caused the drill hole is unknown. The sharp injury at the central part of the valve may be attributed to the attack of a crustacean. This is by far the oldest drill hole reported from a seep deposit, being almost two−and−a−half times as old as the naticid drill holes recognized at a Late Eocene cold seep site on Hokkaido (Amano and Jenkins 2007) .
Stratigraphic and geographic distribution.—Late Cretaceous (Cenomanian to Campanian), Tenkaritoge and Omagari Formations of the Yezo Group, Hokkaido, Japan.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.