genus D dorsoplicatum

New genus D dorsoplicatum (Abich, 1878) Fig. 3A–B Nautilus dorso plicatus Abich, 1878: 23, pl. 2 fig. 6, pl. 3 fig. 1, pl. 4 fig. 8. Coelonautilus dorsoplicatus – von Arthaber 1900: 217. Tainoceras dorsoplicatum – Shimansky 1965a: 41, pl. 14, fig. 1. Remarks Abich (1878) illustrated two fragments as “ Nautilus dorso plicatus, nov. form.”. The first of these (Abich 1878: pl. 4 fig. 8) has a whorl height of about 27 mm. It shows rounded, strongly convergent flanks and a venter with a longitudinal midventral groove about 15 mm wide (Fig. 3B). This groove is bordered on both sides by a slightly raised margin that is decorated with large, blunt nodes. Ventrolateral nodes are obviously lacking. The suture line has a fairly narrow, rounded lobe on the venter and a broad, rounded lobe on the flank. The second specimen (Abich 1878: pl. 2 fig. 3, pl. 3 fig. 1) has a whorl width of about 35 mm (Fig. 3A) and corresponds to the larger one in conch shape and sculpture. The specimen has a broadly rounded umbilical margin. It shows that there are neither ventrolateral nor umbilical nodes; the flank appears to be smooth. New genus D dorsoplicatum occupies a morphologically isolated position in the family Tainoceratidae due to the presence of only a single row of ventral nodes. The species is probably not represented in the new collections from NW Iran.