Pyrgopolon (Septenaria) zitti, Kočí & Jäger, 2015

Kočí, Tomáš & Jäger, Manfred, 2015, Sabellid And Serpulid Worms (Polychaeta, Canalipalpata, Sabellida, Sabellidae, Serpulidae) From The Rocky Coast Facies (Late Cenomanian) At Předboj Near Prague, Acta Musei Nationalis Pragae Series B 71 (1 - 2), pp. 31-50 : 39

Pyrgopolon (Septenaria) zitti sp. nov.

Pl. 2, Fig. 1–4; Pl. 3, Fig. 5

2012c Pyrgopolon sp. 3 – Kočí, p. 126, fig. 1A–C. 2012c Propomatoceros ? sp. – Kočí, p. 124–126, fig. 1D.

D i a g n o s i s: A moderately large-sized species of the subgenus Pyrgopolon (Septenaria) . Attached tube portion has three keels close to each other; the median keel appears as a high and sometimes undulating comb, the other two keels are straight and much smaller. One or two additional rounded longitudinal edges may or may not be present on the latera. No transverse ornamentation. Cross-section triangular.

E t y m o l o g y: In honour of Dr. Jiří Žítt, CSc. (the famous Czech specialist in Mesozoic echinoids, asteroids and crinoids) who studied the geology and paleontology of the Předboj site and other rocky coast localities in the BCB.

H o l o t y p e: The specimen is deposited in the collections of the National Museum in Prague, inventory number NM-O7555 , and figured on Pl. 2, Fig. 1, as the holotype . The specimens with inventory numbers NM-O7556 , O7557, O7558 and O7571 and figured on Pl. 2, Fig. 2, 3, 4 and Pl. 3, Fig. 5 are paratypes .

T y p e l o c a l i t y: Předboj near Prague.

T y p e h o r i z o n: Upper Cenomanian.

M a t e r i a l: At least four specimens representing at least 16 tubes, maybe more.

S u b s t r a t e: Four tubes are attached to an oyster valve, eight tubes are attached to a Spondylus valve and in part to each other (Pl. 3, Fig. 5), two specimens (Pl. 2, Fig. 3–4) each consist of two tubes of which the upper one is attached to the lower one.

D e s c r i p t i o n. Tube moderately large in size. The attached tube portion has three keels situated close to each other; the median keel is developed as a high and, in some tubes, undulating comb, whereas the other two keels are straight and much smaller, but nevertheless distinct. In a few tubes, one or two additional rounded longitudinal ridges may be present on the latera. Otherwise the surface is rather smooth; no transverse ornamentation. Tube triangular in cross-section; lumen circular. One or two specimens, including one of the two tubes shown in Pl. 2, Fig. 4, possess a distinct “ Favosites structure”. However, the other tube shown in Pl. 2, Fig. 4 shows in cross-section depressions at the lateral areas of the base which may be interpreted as tubulae. Tube colour is bright yellow, slightly brighter than in Pyrgopolon gen. et sp. indet.

R e m a r k s a n d r e l a t i o n s h i p s. The welldeveloped keels and the lack of peristomes point to the genus Pyrgopolon , and the presence of a distinct “ Favosites structure” ( Jäger 1983, Jäger and Breton 2002) characteristic for Pyrgopolon (Septenaria) clearly proves affiliation to this subgenus. However the triangular cross-section resembles that of the genera Propomatoceros , Spirobranchus and some fossil specimens of Neovermilia , all of these lacking a “ Favosites structure”. One of the two tubes in Pl. 2, Fig. 4 shows structures which may be tubulae which are known in the above mentioned genera Propomatoceros , Spirobranchus , Neovermilia and others and in the subgenus Pyrgopolon (Pyrgopolon) , but not in the subgenus Pyrgopolon (Septenaria) , making determination of this specimen doubtful, even though its well-developed keels clearly match those of Pyrgopolon (Septenaria) zitti .

Pyrgopolon (Septenaria) sp. A1 ( Kočí 2010) from the rocky coast facies locality Velim differs in its lower, less prominent median keel, a more rounded cross-section and a thinner tube wall. In Pyrgopolon (Septenaria) sp. A2 ( Kočí 2010), also from Velim, the two lateral keels are weakly developed.