Ascheria salina, Kiel & Hybertsen & Hyžný & Klompmaker, 2020

Kiel, Steffen, Hybertsen, Frida, Hyžný, Matúš & Klompmaker, Adiël A., 2020, Mollusks and a crustacean from early Oligocene methane-seep deposits in the Talara Basin, northern Peru, Acta Palaeontologica Polonica 65 (1), pp. 109-138 : 128

Ascheria salina sp. nov.

Fig. 16.

Zoobank LCID: urn:lsid:zoobank.org:act:6BDCBE13-9DA3-4AF0-9366-20014BEA1241

Etymology: For the type locality at Cerro La Salina.

Type material: Holotype: NRM Mo187061 . Paratypes: NRM Mo 187059 from Cerro La Salina block 2 and NRM Mo 187060 from Cerro La Salina block 1 .

Type locality: Cerro La Salina block 1, Talara Basin, Peru .

Type horizon: Presumably the early Oligocene part of the Heath shale.

Material.— The type material and a few unnumbered fragments from Cerro La Salina block 1 .

Dimensions.— Holotype ( NRM Mo187061, H = 22 mm, W = 9 mm) with missing early whorls; fragmentary paratype NRM Mo187060) W = 11.5 mm.

Diagnosis.—Small-sized Ascheria with blunt axial ribs that are opisthocline in lower part of whorls, a weak subsutural incision, and fine spiral incision in early whorls.

Description.—Medium-sized, high-spired cerithiform shell, at least seven slightly convex whorls. Sculpture consists of blunt axial ribs that are straight or slightly oblique in upper half of whorls and become increasingly opisthocline in lower half; ribs have subsutural constriction and blunt tubercles may develop above and below that constriction; early whorls have fine spiral incision but these disappear on whorls wider than 3 mm, later whorls with faint spiral threads; base is smooth except for opisthocyrt growth lines. Aperture appears to be elongate-oval.

Remarks.— Ascheria salina sp. nov. differs from A. elenensis by the shape of the axial ornament, which is strongly opisthocline just below the suture in A. elenensis , whereas the ribs become opisthocline only in the lower half of the whorl in A. salina . Furthermore, A. elenensis grows to a much larger size and appears to be higher spired (having a narrower apical angle) and A. salina has a higher whorl profile than A. elenensis . The Late Jurassic type species A. gigantea differs from A. salina by having spiral ornament also on large whorls, whereas in A. salina such spirals are only present on very early whorls ( Kaim et al. 2014). Ascheria ? sp. from Barbados (including the specimens reported as “cerithid sp.” by Kugler et al. (1984: pl. 7: 6–8), and as Abyssochrysos sp. by Gill et al. (2005: fig. 5D) has more oblique or sloping axial ribs and spiral ornament is also present on large specimens, in contrast to A. salina . As Ascheria ? sp. from Barbados is most likely of Eocene age ( Kiel and Hansen 2015), the early Oligocene Peruvian Ascheria salina is currently the youngest member of the genus; it is also the smallest species of Ascheria .

Stratigraphic and geographic range.— Type locality and horizon only.