Ptychopariid trilobites in the Middle Cambrian of Central Bohemia (taxonomy, biostratigraphy, synecology) VRATISLAV KORDULE A revision of ptychopariid trilobites from the Middle Cambrian of central Bohemia is presented. With a few exceptions, they were previously referred only to Ptychoparia striata. Three genera are recently distinguished: Ptychoparia Hawle & Corda, 1847, Ptychoparioides Růžička, 1940, and Mikaparia gen. nov. Seven species are described: three are revised, four are new, and two is left in open nomenclature; their stratigraphical ranges and significance are discussed. A new stratigraphical subdivision of the Middle Cambrian of the Skryje-Týřovice area is suggested, including three assemblage zones and three barren zones. Four substrate and bathymetrically controlled trilobite associations are recognized in the Skryje-Týřovice area. • Key words: Bohemia, Middle Cambrian, trilobites, new taxa, biostratigraphy. KORDULE, V. 2006. Ptychopariid trilobites in the Middle Cambrian of Central Bohemia (taxonomy, biostratigraphy, synecology). Bulletin of Geosciences 81(4), 277–304 (13 figures). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received February 17, 2005; accepted in revised form December 4, 2006; issued December 31, 2006. Vratislav Kordule, Dlouhá 104, 261 01 Příbram III, Czech Republic; [email protected] Representatives of the genera Ptychoparia Hawle & Corda to study the materials in Vokáč’s private collection, the 1847, Ptychoparioides Růžička, 1940, and Mikaparia gen. specimens described and figured by Vokáč (1997) can be nov. are significant components of the trilobite fauna of identified, and their taxonomic position is revised. the Middle Cambrian marine deposits in the Jince and Following the previous stratigraphical models (their Skryje-Týřovice areas. Specimens referred to these taxa summary is given in Havlíček 1998 and Fatka et al. 2004, were already described in part by Emmrich (1839), but a Fatka 2006), Fatka & Kordule (1992), and Kordule (1996), modern revision has appeared necessary since the paper presented a detail biostratigraphical scheme for the Middle of Šnajdr (1958). It is apparent that some formerly descri- Cambrian of the Jince area, based on distribution of index bed ptychopariid species constitute so-called “cumula- trilobites. A similarly detailed stratigraphy of the Middle tive” taxa. Cambrian in the Skryje-Týřovice is missing. Stratigraphi- Several authors have studied this trilobite group on ma- cal schemes of the Middle Cambrian of the Skryje-Tý- terial from Central Bohemia. The earliest detailed study by řovice have been presented by Kettner (1923), and refined Barrande (1852) was followed by the contributions of by Šnajdr (1958) and Havlíček (1971, 1998), but all are too Pompeckj (1896), Jaekel (1901), Růžička (1940, 1944), general. The taxonomical revision of ptychopariid species Richter (1940), and Šnajdr (1958, 1982). Růžička (1940) with a compilation of their distributive data allows some described several new genera and species from the basal corrections and additions to actual stratigraphic subdivi- Mileč Sandstone from the Na Kamenných hůrkách locality sion of the Middle Cambrian in the Skryje-Týřovice area; near Týřovice in the Skryje-Týřovice area. However, the some ptychopariids are the valuable index species. majority of these species has been based on tectonically de- formed specimens. Richter (1940) and Šnajdr (1958) criti- cally evaluated this article. Both authors referred all of Material and methods Růžicka’s species to the genus Ptychoparia and to the spe- cies Ptychoparia striata (Emmrich, 1839). A new study The specimens of studied collections are preserved in a va- of the original and new material confirmed the validity of riety of rock types, from coarse-grained quarzitic sand- some taxa described by Růžička (1940, 1944), primarily stone, greywacke, de-calcified siltstone, mudstone to car- of the genus Ptychoparioides Růžička, 1940. Vokáč (1997) bonatic nodules. Some specimens from fine-grained also studied ptychopariids, but there are some uncertainties sediments show minute details (tubercles, genal caeca) that in his systematic. Although the present author was unable are absent in those coming from coarse-grained rocks. 277 Bulletin of Geosciences Vol. 81, 4, 2006 Most of the specimens are slightly tectonically distorted; 3. the morphology of the pleural lobes on the pygidium; therefore the biometrical data are employed with a caution. 4. the number of pygidial axial rings. Locality names are consistent with names used by Based on these features, three morphological groups Šnajdr (1958; pp. 25–29) and Fatka & Kordule (1992). All that likely represent particular evolutionary lineages have figured specimens are covered by ammonium chloride if been distinguished. The first lineage (Ptychoparia Group) not otherwise stated. comprises several species of Ptychoparia, some of which Abbreviation of the collections: NM – Palaeontological are rare and insufficiently known. The second lineage (Mi- collections of the National Museum, Prague; ČGÚ MŠ – kaparia Group) comprises two species. The third lineage Palaeontological collection of M. Šnajdr stored in the (Ptychoparioides Group) comprises three species, al- Czech Geological Survey, Prague; ČGÚ VK – Author’s though Šnajdr (1958) synonymised Ptychoparioides Rů- collection stored in the Czech Geological Survey, Prague; žička, 1940 with Ptychoparia and all species of Ptycho- ČGÚ XB – Palaeontological collection of the Czech Geo- paroides considered invalid. Members of all three lineages logical Survey, Prague. have been observed in a substantial part of the Middle Cambrian succession in central Bohemia, and are present both in the Jince and Skryje-Týřovice areas. Systematic part By comparing the original and the new specimens it has been observed that the diagnoses of the genus Ptychoparia Superfamily Ptychopariacea Matthew, 1887 given by Barrande (1852) and Šnajdr (1958) involved Family Ptychopariidae Matthew, 1887 lumping particular species of the Ptychoparia and Mika- Subfamily Ptychopariinae Matthew, 1887 paria lineages. Their diagnoses therefore do not reflect the actual morphology of Ptychoparia. Some specimens used in their diagnoses are now grouped into the new genus Genus Ptychoparia Hawle & Corda, 1847 Mikaparia sp. nov. In addition, new specimens that are comparable with those studied by Růžička (1940) indicate Type species.–Conocephalus striatus Emmrich, 1839; the validity of Agraulopsis resseri, the species referred by Middle Cambrian, Bohemia, Czech Republic. Šnajdr (1958) to P. striata; the revision of this species is out of scope of the present paper. Emended diagnosis (Šnajdr 1958). – Glabella tapering for- ward, with weakly rounded anterior; four pairs of glabellar Species included.–Ptychoparia striata (Emmrich, furrows; cephalic border prominent, rather long (sag.); ante- 1839); Middle Cambrian, Bohemia, Czech Republic. rior border furrow deep; genal spine prominent, short, rapidly Ptychoparia dubinka sp. nov.; Middle Cambrian, Bohe- tapering, extending backward toward the third segment; genal mia, Czech Republic. Ptychoparia cf. striata (Emmrich, caeca prominent on external surface of preglabellar field, pre- 1839); Middle Cambrian, Bohemia, Czech Republic. ocular field of fixigenae and librigenal field of librigenae; Ptychoparia? sp. A.; Middle Cambrian, Bohemia, Czech pygidium with 5 to 6 axial rings and terminal piece; pleural Republic. lobes with distinct pleural and interpleural furrows; exoskele- ton surface with finely tuberculate sculpture. Ptychoparia striata (Emmrich, 1839) Discussion. – E. & R. Richter (1941, p. 53) selected Pty- Figures 1A–M, 2J, K choparia sternbergiana Boeck, 1827 as the type species. However, this species is considered to be a nomen dubium 1825 Trilobites Sulzeri var. γ. – Sternberg, pl. 2, fig. 1 A. (see Šnajdr 1986, p. 21). Neither the subsequent descripti- 1839 Conocephalus striatus Emmrich; Emmrich, p. 43. ons of the cranidium and the pygidium given by Šnajdr 1847 Ptychoparia striata nob. – Hawle & Corda, p. 25, pl. (1958), nor his generic diagnosis of Ptychoparia are cor- 2, fig. 11. rect because of a mismatch of the features of more than one 1852 Conocephalites striatus Emmrich. – Barrande (par- species. The revised taxonomy therefore requires an emen- tim), pl. 14, fig. 3, non figs 1, 2, 4–7. ded diagnosis for the genus Ptychoparia. 1896 ?Solenopleura spec. – Pompeckj, pl. 15, fig. 21. The most valuable morphological features of the dorsal 1906 Ptychoparia striata Emmrich. – Lorenz, p. 58. exoskeleton of Ptychoparia and allied genera that are used 1940 Ptychoparia lobifera Růžička; Růžička, p. 4, pl. 1, for their classification are: figs 10–12. 1. the length of cranidium (sag.) relative to the length 1940 Ptychoparia gracilis Růžička; Růžička, p. 4, pl. 1, (sag.) of the anterior border (LCr/LAB index); figs 13–15. 2. the morphology of the genal caeca and the sculpture 1940 ?Lobocephalus cylindricus Růžička; Růžička, p. 9, of the cephalon; pl. 1, fig. 22. 278 Vratislav Kordule Ptychopariid trilobites in the Middle Cambrian of Bohemia 1940 Ptychoparioides nobilis Růžička; Růžička (partim), led Vinice or Vystrkov Hill (determination based on litho- p. 5, pl. 2, fig. 5. logy and mode of preservation). 1952 Ptychoparia striata (Emmrich). – Prantl, fig. on p. 261. 1953 Ptychoparia striata (Emmrich, 1839). – Přibyl, p. 62. Material. – Several tens of complete specimens and other 1953 Ptychoparia gracilis Růžička. – Přibyl, p. 62. parts of