Abyssomelania campbellae, Kaim, Andrzej, Jenkins, Robert G., Tanabe, Kazushige & Kiel, Steffen, 2014

Kaim, Andrzej, Jenkins, Robert G., Tanabe, Kazushige & Kiel, Steffen, 2014, Mollusks from late Mesozoic seep deposits, chiefly in California, Zootaxa 3861 (5), pp. 401-440 : 416

Abyssomelania campbellae sp. nov.

( Fig. 6 G–N)

Type locality and strata: Cold Fork of Cottonwood Creek, Tehama County, California, USA; locality # 1 in Kiel et al. (2008b); Lodoga Formation, Great Valley Group; Albian (Early Cretaceous.)

Holotype: GZG.INV.84982, two and half well-preserved adolescent whorls 33.1 mm high and 19.3 mm wide.

Paratypes: GZG.INV.84983, two adult whorls 39 mm high and 30.2 mm wide, we estimate that the complete specimen could be 80 mm high, GZG.INV.84984 fragmentary specimen displaying the ornamentation on the shell base.

Additional material. Five fragmentary specimens from the type locality including juvenile (GZG.INV.84985) illustrated in Fig. 6 N.

Diagnosis. Large tall gastropods (reaching 80 mm in length) with smooth lateral flanks of adolescent/adult shell and spirally ornamented base. Growth lines opisthocline throughout the entire lateral flank. Shell largest diameter slightly above abapical suture.

Description. Tall shell with largest diameter of whorl slightly above the abapical suture. Shell surface smooth with opisthocline growth lines only and abyssomelanid riblets at least at last two whorls. Shell base ornamented by five broad spiral ribs intersected by growth lines with no knobs. Suture weakly incised. Protoconch, juvenile teleoconch and aperture not preserved.

Remarks. A. campbellae differs from A. cramptoni by its much larger size, and its stronger and less numerous spiral ribs on the base. The largest diameter of the whorl is only slightly above the abapical suture giving less bulgy appearance than in A. cramptoni . The angulation of the growth lines is in the middle of lateral flank in A. campbellae while in the upper part in A. cramptoni .

Etymology. For Kathleen A. Campbell, for her pioneering work on the fossil seep faunas of California.

Figures

FIGURE 6. A – E. Abyssomelania cramptoni sp. nov. from Campanian (Late Cretaceous) seep carbonates at Waipira III, New Zealand. A. Paratype (GNS TM 8851). B. Paratype (GNS TM 8850), C. Paratype (GNS TM 8853). D. Holotype (GNS TM 8852), the arrow indicates the abyssomelanid riblet. E. Juvenile (GNS TM 8927). F. Hokkaidoconcha occidentalis (Stanton, 1895) from Tithonian (Late Jurassic) seep carbonates at Paskenta, Tehama County, California, USA; GZG. INV. 84981. G – N. Abyssomelania campbellae sp. nov. from Albian (Early Cretaceous) seep carbonates at Cold Fork of Cottonwood Creek, Tehama County, California, USA. G – H. Paratype (GZG. INV. 84983). I-K. Holotype (GZG. INV. 84982). L – M. Paratype (GZG. INV. 84984). N. Paratype (GZG. INV. 84985).