Kinnekulloceras, Kröger, 2004

Kröger, Björn, 2004, Revision of Middle Ordovician orthoceratacean nautiloids from Baltoscandia, Acta Palaeontologica Polonica 49 (1), pp. 57-74 : 70

Genus Kinnekulloceras nov.

Type species: Orthoceras kinnekullense Foord, 1887 .

Diagnosis.— Kinnekulloceras resembles Nilssonoceras in most features but strongly differs in its ornamentation. The shell shows a transversal striation with smooth, flat ribs and fine sharp deepened lines in between. The distance apart of the ribs or ribblets is about 1 mm or lower. The relatively wide tubular siphuncle is subcentral to midventral in position. The septal necks are short orthochoanitic – orthochoanitic. The endosiphonal deposits are highly variable but generally consist of annuli at the septal foramen which may fuse and form an irregular endosiphuncular lining. The cameral and endosiphuncular deposits are more strongly developed at the dorsal side of the conch.

Remarks.—Like Nilssonoceras , the genus Kinnekulloceras differs from all other Geisonoceratidae in its distinct ornamentation. The endosiphuncular and cameral deposits are strongly variable. The genus includes only one species: Kinnekulloceras kinnekullense ( Foord, 1887) .

Fig. 13. Shape of the Middle Ordovician Orthoceratacaea. A. Plagiostomoceras laevigatum (Boll) , NMB C. 5385, coll. Patrunky, not numbered, × 0.95. Ą B. Plagiostomoceras laevigatum (Boll) , NRM Mo 31300, Sandby (Öland), note the major sublethal injury at the left flank, × 1. C. Nilssonoceras nilssoni (Boll) , NRM−Mo 3348a, living chamber and part of the phragmocone, × 0.3. D. Archigeisonoceras repplingense sp. nov., NRM−Mo 3284, Räpplinge (Öland), subadult specimen, × 0.85. E. Archigeisonoceras repplingense sp. nov., NRM−Mo 3245, Räpplinge (Öland), holotype, living chamber and parts of the phragmocone, × 1. F. Plagiostomoceras fragile sp. nov., NRM−Mo 160560, part of the phragmocone, × 1. G. Plagiostomoceras fragile sp. nov., NRM−Mo155529, Böda, Stora Mossen (Öland), holotype, living chamber and last four gas chambers, × 1. H. Nilssonoceras nilssoni var. wahlenbergi (Boll) , NRM−Mo 3344, Hulterstad (Öland), living chamber and part of the phragmocone, × 0.5. I. Archigeisonoceras picus sp. nov., NRM−Mo 14455a–c, holotype, Resmo (Öland), living chamber and part of the phragmocone, × 0.7. J. Archigeisonoceras folkeslundense sp. nov., NRM−Mo 3220 (Öland), conve× side of the septum with thin horseshoe−like hyposeptal deposits leaving a tongue−like space between siphuncle and shell rim, × 1.1. K. Archigeisonoceras folkeslundense sp. nov., NRM−Mo 155476, 155477, holotype, Folkeslunda (Öland) adult specimen with preserved parts of the living chamber and the phragmocone, × 0.3. L. Arionoceras lotskirkense sp. nov., NRM−Mo 154080, Löts Kirka (Öland), part of the living chamber, × 1.4. M. Arionoceras lotskirkense sp. nov., NRM−Mo 154079, Löts Kirka (Öland), living chamber and part of the phragmocone, × 1.