Cycloneritimorpha Bandel and Frýda, 1999

Jagt-Yazykova, Elena, Krawczyński, Wojciech & Rakociński, Michał, 2006, Molluscs from the Early Frasnian Goniatite Level at Kostomłoty in the Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 51 (4), pp. 707-718 : 714

Order Cycloneritimorpha Bandel and Frýda, 1999 Family Neritopsidae Gray, 1847

Naticopsis aff. N. kayseri Holzapfel, 1895 ( Fig. 5E, K ).— Two well−preserved pyritised shells with protoconchs (a diameter of 0.3 mm; see Fig. 5E 4 ) have been found. The specimens studied closely resemble N. kayseri described by Holzapfel (1895) from Givetian limestones of Martenberg (Rhenish Slate Mountains). However, they have a lesser developed ultimate whorl, with the aperture occupying two−thirds of the shell width. These specimens are similar to the ones identified by Heidelberger and Koch (2005) as Naticopsis aff. N. kayseri Holzapfel, 1895 (see pl. 15: 12). This species belongs to the genus Naticopsis with some doubts because of absent well preserved operculum. This genus has a concentric operculum, and it is main difference from the near−identical (in shell shape) Givetian genus Hessonia Heidelberger, 2001 , which has a paucispiral one. The specimens studied originate from the Goniatite Level at Kostomłoty (uppermost Szydłówek Beds; Early Frasnian). Naticopsis kayseri has been recorded from the Givetian of Eisenstein and Martenberg ( Holzapfel 1895), and from Schwelm (Reinish Slate Mountains; see Heidelberger and Koch 2005).

Figures

Fig. 5. Gastropods from the Early Frasnian Goniatite Level (uppermost Szydłówek Beds) at Kostomłoty, Holy Cross Mountains, Poland. A–C. Lahnospira taeniata (Sandberger, 1842). A. GIUS 4−2282 Kos−12 in apertural view. B, C. GIUS 4−2276 Kos−6 (B) and GIUS 4−2277 Kos−7 (C) in lateral views. D. Subulitidae indet., GIUS 4−2289 Kos−19, in apertural (D1) and lateral (D2) views, with protoconch visible. E, K. Naticopsis aff. N. kayseri Holzapfel, 1895. E. GIUS 4−1164 Kos−2 in pertural (E1), lateral (E2), and apical (E3) views and cycloneritid−type protoconch (E4). K. GIUS 4−2288 Kos−18 in apertural (K1) and lateral (K2) views. F–J. Palaeozygopleura (Bohemozyga) pyritica sp. nov. H. GIUS 4−2284 Kos−14 in apertural (H1) and lateral (H2) views of holotype. F, G, I. GIUS 4−2287 Kos−17 (F). GIUS 4−2285 Kos−15/1 (G), and GIUS 4−2286 Kos−16 (I), lateral views with opisthoclinal ornamentation visible. J. GIUS 4−2285 Kos−15/1, apertural view of shell fragment.

Fig. 4. Indeterminate parts of phragmocones and juvenile forms of nautiloids and bactritids from the Goniatite Level, uppermost Szydłówek Beds (Early Frasnian) at Kostomłoty, Holy Cross Mountains, Poland. A–C. Fragments of bactritid shells, GIUS 4−2832 Kos−50/1 (A), GIUS 4−2832 Kos−50/2 (B), and GIUS 4−2832 Kos−50/3 (C). D. Bactritid protoconch, GIUS 4−2832 Kos−50/4. E. Fragment of nautiloid phragmocone, GIUS 4−2306 Kos−36/1. F. Cross−section of bactritid shell, GIUS 4−2832 Kos−50/5. G. Nautiloid shell, GIUS 4−2580 Kos−47.