Pyrgopolon (Septenaria) ziegleri KOČÍ

Kočí, Tomáš, 2012, Sabellidae And Serpulidae (Polychaeta, Canalipalpata) From The Locality Kaňk - Na Vrších In Kutná Hora (Upper Cenomanian - Lower Turonian, Bohemian Cretaceous Basin - The Czech Republic), Acta Musei Nationalis Pragae Series B 68 (1 - 2), pp. 7-14 : 11

Pyrgopolon (Septenaria) ziegleri KOČÍ

Pl. 1, figs 2a-b

2010 Pyrgopolon ziegleri sp. n. – Kočí: p. 125, figs 7-8.

M a t e r i a l: One complete specimen. Two fragments of tube.

D e s c r i p t i o n: Fixed tube portion large, smooth, triangular in cross-section, bears a distinct median keel. There is no transversal ornamentation. Tube width at the anterior end of the base 13.2 mm, corresponding tube height 12.6 mm. Towards the posterior, the tube is considerably narrower, and the height is only 6.7 mm. Lumen circular, 3.96 mm in diameter. The lumen is situated in an excentric position, near to the keel. Immediately below the aperture, there is a smaller tall but narrow chamber measuring circa 2 mm, and between that chamber and the tube’s base there is a fine groove. Free tube portion is unknown.

D i s c u s s i o n: This species includes the largest specimens with triangular cross-section in the BCB and is characterized by its shape and size. Pyrgopolon (Septenaria) ares (ZIEGLER) differs by the position of its lumen and by its narrower longitudinal keel. Pyrgopolon sp. A 1, Pyrgopolon sp. A 2 and Pyrgopolon sp. B from the nearshore locality Velim (see Kočí, 2007a) differ also in the position of the lumen, and partly by their tube morphology. Pyrgopolon (Septenaria) marechali (JÄGER et BRÉTON) from the Lower Cenomanian of Normandy, France, is even larg- er, and its tube is much more rounded. Pyrgopolon (Septenaria) polyforata (JÄGER) differs by its specific ornamentation. Pyrgopolon (Septenaria) macropus (SOWERBY) has a pentagonal to heptagonal cross-section and a more prominent keel ( Jäger, 2005, pl. 9, fig. 5a). The tube of Pyrgopolon (Septenaria) macropus is attached to the substrate by its posterior tube portion and its anterior tube portion is erect above the substrate. The same is seen in Pyrgopolon (Septenaria) erecta (GOLDFUSS) , which is distinguished by its larger tube diameter which may reach 14 mm. The subgenus Pyrgopolon (Septenaria) is most common in transgression facies (Jäger, personal communication).