Cataegis nakagawensis, Kaim & Jenkins & Hikida, 2009

Kaim, Andrzej, Jenkins, Robert G. & Hikida, Yoshinori, 2009, Gastropods from Late Cretaceous Omagari and Yasukawa hydrocarbon seep deposits in the Nakagawa area, Hokkaido, Japan, Acta Palaeontologica Polonica 54 (3), pp. 463-490 : 478-479

Cataegis nakagawensis sp. nov.

Fig. 9 .

Etymology: After Nakagawa town, located close to the type locality.

Holotype: UMUT MM30175 , Fig. 9A , moderately preserved shell with no protoconch.

Type locality: Omagari site, Nakagawa area , Northern Hokkaido, Japan. Coordinates 44 ° 39’26’’ N, 144 ° 2’25’’ E .

Type horizon: Fossil hydrocarbon seep deposits of Omagari Formation, Campanian, Upper Cretaceous.

Material.—Four moderately preserved specimens without protoconchs.

Dimensions.—The holotype is 4.1 mm high and 4.91 mm

wide. Diagnosis.—Shell turbiniform, whorls ornamented with beaded spiral cords. Two of the cords form spiral keels on the lower part of the flank. C. nakagawensis differs from other species of the genus by having two distinctly keeled cords.

Description.—The protoconch is not preserved. The shell is turbiniform with whorls ornamented by six spiral cords. Two of them are stronger transforming into two keels. The lower keel is located at the angulation demarcating the flank from the base, while the other one is located slightly below the mid part of the flank. There are three cords above the upper keel and one cord between the keels. The base is ornamented by five beaded spiral cords. There is no umbilicus and the aperture is poorly preserved.

Discussion.—The shells under consideration are provisionally classified as Cataegis because they lack an umbilicus and posses strong spiral cords on the flank and also on the base. Cataegis has not been noted so far from Japan. The nearest extant occurrences are C. leucogranulata from Taiwan ( Fu and Sun 2006) and C. celebesensis from Indonesia ( McLean and Quinn 1987).

Stratigraphic and geographic range.—Omagari hydrocarbon seep in Nakagawa area of northern Hokkaido, Japan. Campanian, Upper Cretaceous.

Figures

Fig. 9. The seguenzioid gastropod Cataegis nakagawensis sp. nov. from the Campanian (Upper Cretaceous) Omagari seep site in Hokkaido, Japan. A. Holotype (UMUT MM30175) in apertural (A1), lateral (A2), and umbilical (A3) views. B. UMUT MM30176 in apical (B1), lateral (B2, B3), and latero−apical (B4) views. C. UMUT MM30177 in apical (C1), lateral (C2, C3), latero−umbilical (C4), and latero−apical (C5) views.