paper.ms

New polycystine radiolarian from the latest Eifelian of Bohemia

Peter A. Cejchan
Lab of Paleobiology and Paleoecology, Institute of Geology, Academy of Sciences, CZ
Rozvojová 269, CZ-16502 Praha, Czechia, EU
<cej@gli.cas.cz> http://www.gli.cas.cz/home/cejchan

ABSTRACT

Abstract A unique polycystine radiolarian representing a new species belonging probably to Entactiniidae: Stigmosphaerostylus, has been recovered from a single sample of black limestone nodules, occurring in the early Kačák Mb of the Srbsko Fm in the vicinity of the village Hostim near Beroun, Barrandian, Prague Basin, Czechia. Its age is almost certainly the latest Eifelian, T. kockelianus kockelianus Zone (proved at the locality about 10 km apart). Accompanying biota consists of spicules of hexactinellid sponges, mazuelloids (Papinochium), and rare conodont fragments (Polygnathus, ####). Keywords: Radiolaria, Polycystina, Devonian, Eifelian, otomari-Event, Barrandian.

Introduction

Radiolarians from the Srbsko Fm of Prague Basin (Barrandian, Bohemia, CZ) were first mentioned by Wähner, 1917 from thin sections of the chert beds belonging to the early Kačák Mb of the 'Hlubočepy-railway cut' locality. Although the presence of radiolarians in the Kačák Mb. was repeatedly reported (Petránek, 1946; Chlupáč 1960; Chlupáč et al., 1992; Budil, 1995), and some effort has been spent to unveil isolated radiolarians from residues of carbonate nodules derived from the early Kačák Mb. black shales, this is the first time when a 3D-preserved radiolarian occurrence is published. It is derived from locality, Hostim (Beroun, CZ), N49:57.915 E14:08.338 altitude 358m a.s.l.. It is a cut of the forest path from Hostim to 'Propadlé vody', on the northern foot of the 'Vysoká stráň' Hill (not to be confused with the well-known contemporaneous locality of fossil terrestrial plants, also in the vicinity of Hostim, nor with the locality Hostim of Budil 1995). Black shales with sporadic limestone nodules, belonging to early Kačák Mb of the Srbsko Fm, ?late T. kockelianus kockelianus Zone, crop out there. The fossiliferrous sample PAC-SMP-16 that yielded the biota mentioned herein is derived from a dark limestone nodule within black Kačák Mb. shales. Naming of the new species is PhyloCode ready, although ICZN/ICBN conformant name is also provided. For reasons why to use PhyloCode, see ####

Stratigraphy

Stratigraphically, the locality belongs to the Middle Devonian Kačák Mb.of the Srbsko Fm (text-fig. ###). The Srbsko Fm. was defined by Krejčí (1877) as the lower part of Barrande's (1852, 1865) Etage H redefined by Svoboda & Prantl (1950).

The base of the Srbsko Fm is delimited by a sudden onset of dark shales on the limestones of the latest Choteč Fm, interpreted due to change in biota of dacryoconarids, nautiloids, bivalves, and trilobites as the global otomari-Event (Walliser 1984, Walliser et al, 1995) =Kačák-Event (House 1985) of transgressive, anoxic character. The Srbsko Fm. consists of two members, the earlier Kačák Mb., and the later Roblín Mb. Kačák Mb. was established by Svoboda & Prantl (1950), and studied litho-, bio-, and eventostratigraphically by Chlupáč 1960, Chlupáč & Kukal 1986, 1988 Chlupáč, Lukeš & Zikmundová 1977 Klapper, Ziegler & Mashkova 1978; Budil 1995, Kalvoda 1992 Hladil et al. 1992a, 1992b, 1993, Hladil 1993, Hladil & Kalvoda1993, Galle 1994, sedimentologically by Chlupáč & Kukal 1986, 1988, Jager 1986, and Oczlon 1992. See Chlupáč et al., 1992, for a review. According to conodonts from related localities ###, the lower boundary of the KAC lies somewhere in tyhe uppermost part of the kockelianus Zone. However, if the correlation of the Jirásek (= Jíras) Quarry presenter by Budil 1995 is correct, then, according to findings of P. eiflius, and P. ensensis well below the onset of the presumed 'Kacak-Event' (dark interval of beds ##-## there, the top of the CHO may well lie within the eiflius, or ensensis Zones (Hladil et al. 1993, Kauffmann 2006). According to the dacryoconarid stratigraphy, base of KAC is synchronous with the base of the Nowakia otomari Biozone (Bouček 1964, Chlupáč, et al 1992).

Facially, Kačák Mb. spans from deep-water marine sediments at NE, to shallow water ones on the SW. (cf. text-fig. ###), following the general trend in the Devonian of the Barrandian (Chlupáč et al., 1992). Biostratigraphically, at least the lower part of the Kačák Mb still belongs to the Eifelian, T. kockelianus kockelianus Zone (proved at Volfova Rokle and Hlubočepy by Chlupáč, Lukeš & Zikmundová 1977 and Klapper, Ziegler & Mashkova,1978 ), but apparently the onset of Kačák Fm is not far before the base of the P. ensensis Zone (Kalvoda 1992; Chlupáč & Kukal 1986) thus not far before the FAD of P. hemiansatus, defining the base of the Givetian Stage. Kalvoda (1992) found Polygnathus cf. xylus and Polygnathus cf. eiflius at ''Volfova rokle" Gorge, near the base of Kačák Fm. It is in concordance with the positioning of the global end-Eifelian transgression. However, ####

Abundant dacryoconarids document the N. otomari Zone. Other biota, ascertained nearby sections of the same facial development, is also of end-Eifelian age (see lists in Chlupáč1960; Budil, 1995). However, until the ejecta layer (Ellwood et al 2003), and/or Polygnathus hemiansatus is ascertained here, the uncertainty about how far we are from the Eifelian/Givetian boundary lingers on. The biota accompanying the radiolarian occurrence is of low stratigraphic importance, as it remains undetermined (conodonts Polygnathus ##-element, ? Ozarkodina; Papinochium (Mazuelloida) - this is probably what is called "foraminiferans of Endothyra-type" by Svoboda & Prantl 1952; and sponge spicules assigned with caution to Pyritonema (Hexactinellida).

Material and methods

All material published herein is derived from the sample PAC-SMP-16, dark limestone nodule within black Kačák Mb. shales, Hostim (Beroun, CZ), N49:57.915 E14:08.338 altitude 358m a.s.l., a cut of the forest path from Hostim to 'Propadlé vody', on the northern foot of the 'Vysoká stráň' Hill. All specimens are deposited in the collections of the Laboratory of Paleoecology and Paleobiology, Institute of Geology, Academy of Sciences, Prague, CZ, EU, under numbers LHC-10001 to LHC-10064. About 200g total of limestone was dissolved in 6% acetic acid, residue was sieved on a set of 500 - 250 - 100 μm sieves, fractions washed in ethylalcohol and dried at 105 °C. The 250 - 100 μm fraction was inspected under optical stereomicroscope, reflected light on dark background, magnification ×40. The microfossils were picked up with an stick-mounted hair, and mounted on xylene-thinned conductive carbon cement on Al-stubs for electron microscopy. Snapshots of selected specimens were taken under the SEM microscope JEOL JXA-50A, ##### electrons, as stereopairs using stereoscopic angle of 10°. Red-cyan anaglyphs were constructed using 'anaglyph' program, available at ftp://ftp.gli.cas.cz/cej/neXt/graphics/anaglyph-1.01.tbz. Use red-cyan anaglyph spectacles (e.g., from Agar Scientific, O665, O668, O6270, O6271), red on left eye, to see the stereoscopic effect.

Phylogeny

Radiolaria are (usually) unicellular, exclusively marine eukaryans, representatives of one of the branches of probably explosive bikont radiation dated to late Neoproterozoic. In original sense (Müller,1858; Haeckel 1862, 1881, 1887) they contain Polycystina+Acantharea+Phaeodarea, and are polyphyletic (Polet et al. 2004, Nikolaev et al. 2004). As recently "redefined" (López-Garcia 2002), they comprise Polycystina and Acantharea as adelphotaxa (if retained in original sense, then based on common ancestry, not content, they would become identical with core Rhizaria). However, they should also include Sticholonche, as indicated by a study of Cavalier-Smith 1998a (but contrary to Mikrjukov et al. 2002), and also supported by recent molecular studies (Nikolaev et al. 2004). Their sister group (adelphotaxon) are very probably Foraminifera(#cite), forming together a clade of Retaria, one of two sisters of "core Rhizaria" (Cavalier-Smith & Chao, 2003a).

Opinions on eukaryan phylogeny underwent almost a U-turn during the late nineties, and the first years of the 21st century. The definitive picture has not been achieved yet, although the main phylogenetic scheme seems to be stabilized. Some ten years ago the eukaryan phylogenetic tree based on molecular sequences of SSU rRNA seemed to be intuitively acceptable. It placed usually unicellular organisms of simple construction basally, while complex multicells like animals, fungi and plants formed the so-called "eukaryotic crown" (Sogin 1991). The tree root has been placed amongst amitochondrial eukaryans. However, according to subsequent studies (Philippe and Adoute, 1996, 1998; Embley-Hirt, 1998; Roger, 1999; Philippe et al, 2000) , this scheme was probably a methodical artifact caused by rapidly evolving lineages (LBA: long branch attraction effect) . After the existence of extant ancestrally amitochondriate forms has been repeatedly questioned (and later abandoned), the phylogenetic scheme collapsed into a single big radiation (Philippe et al. 2000). Recent few years then shed some substantial light on the structure of this radiation. Tracing of synapomorphies unveiled several new huge groupings (Cavalier-Smith 2002). The traditionally heaviest question, i.e., where the eukaryotic root should be placed, was almost solved by tracing DHFR-TS gene fusion among almost all big eukaryotic groups (Stechmann & Cavalier-Smith 2002). The only possible place for eukaryotic root is between opisthokont/bikont branching-off, with still poorly resolved position of amoebozoans. When the anterokont hypothesis (Cavalier-Smith 2002b) turns out to be well-supported, than the position of eukaryotic root at te opisthokont/anterokont bifurcation should be accepted (Stechmann & Cavalier-Smith 2003; see text-fig. ###).

Radiolaria were delimited as a group by Müller (1858), originally including Polycystina, Acantharea, and Phaeodarea. Opinions on its phylogenetic position differed much through time. Calkins 1902 grouped Radiolaria with Heliozoans into Actinopoda, now clearly shown to be polyphyletic (Patterson, 1999; Amaral Zettler 1997; Febvre et al., 2000; Polet et al., 2004; Nikolaev et al., 2004). Also the monophyly of radiolaria has often been questioned; however, modern molecular analyses (López-Garcia, 2002, 2003; Cavalier-Smith & Chao, 2003b; Polet et al., 2004), after moving Phaeodarea to Cercozoa, support monophyly of Polycystina+Acantharea. Nevertheless, Sticholonche should also be included (Cavalier-Smith & Chao, 2003a), otherwise the group would become paraphyletic, as shown by Nikolaev et al. 2004. Sticholonche was first described as a member of an empty taxon Taxopodida, later included within Radiolaria (at that time including Phaeodarea) (Hollande, Cachon, Cachon & Valentin, 1967)) due to morphoological organization, later moved to polyphyletic (Cavalier-Smith & Chao, 2003a; Nikolaev et al. 2004) Heliozoa on ultrastructural evidence (Cachon & Cachon 1978, Margulis et al., 1990, Lee, Leedale & Bradbury, 2000), but transferred back to emended Radiolaria recently (Cavalier-Smith 1998a; Nikolaev et al. 2004).

As early as in the beginning of 20th century radiolarians were placed to the vicinity of foraminiferans; this concept has been proved recently (Cavalier-Smith 1999, 2002; Cavalier-Smith & Chao (2003b) ) in the election of the clade Retaria, which comprises both these groups and is very probably the sister of Cercozoa. Together with them, it forms an emended clade of Rhizaria (=core Rhizaria of Cavalier-Smith 2000b). Core Rhizaria with Excavata form Cabozoa, which are very likely the sister of plant-chromalveolate clade Corticata (Stechmann & Cavalier-Smith 2002, 2003). The most recent eukaryan phylogeny was published by Cavalier-Smith & Chao (2003b).

The phylogenetic hypothesis adopted herein (see text-fig. ###) is synthesized from recent publications, and presented in the form of supposedly holophyletic, rankless units, clades, ready - after proper definition and registration - for subsequent inclusion to the PhyloCode (PhyloCode, 2003). The vacant taxa (containing a single subtaxon) are omitted, as recommended, e.g., by Ax ####.

Descriptions of species

coronella , n. sp. (PhyloCode-ready uninomial), or ?Stigmoshaerostylus coronella , n. sp. (ICZN/ICBN conformant#ing? binomial)

Phylogenetic position:

Panbiota (Wagner 2005) Unibacteria Cavalier-Smith 1998 Biol Rev Camb Philos Soc Neomura Cavalier-Smith 1987b Ann NY Acad Sci Eukarya Woese et al. 1990 Anterokonta Cavalier-Smith 2002b Bikonta Cavalier-Smith 1993 Photokarya Cavalier-Smith 2002 Cabozoa Cavalier-Smith 1999 core Rhizaria Cavalier-Smith 2000b Retaria Cavalier-Smith 1999 Radiolaria (Mueller 1858) López-Garcia 2002 Polycystina Ehrenberg 1838, Riedel 1967b Spumellaria Ehrenberg 1875 ?Sphaerellaria Haeckel 1881 Entactiniaceae Riedel 1967 @nebo -cae Entactiniidae Riedel 1967 Stigmosphaerostylus Ruest 1892 (= Entactinia Foreman 1963) Etymology:

coronella (lat.) = small crown, referring to characteristic shape formed by pore walls.

Supposed apomorphies:

- no exterior spines; - pores surrounded by a wall, projecting to small tips forming a delicate "corona" (hence name) around circular pores.

Description:

spherical shell ### μm in diameter with rounded, usually perfectly circular to slightly elliptic pores ### - ### μm in diameter (ca 26 pores per circumference). Pores are ± regularly spaced, varying in diameter, surrounded by a wall projecting into short, but robust tips, usually situated at triple-points. Medullary shell not observed, presumably absent. Interior spicule assumed, but not observed.

Dimensions:

#### Material: single almost complete specimen.

Type locality and bed:

Hostim (Beroun, CZ), N49:57.915 E14:08.338 altitude 358m a.s.l.. A cut of the forest path from Hostim to 'Propadlé vody', on the northern foot of the 'Vysoká stráň' Hill. Black shales with sporadic limestone nodules, early Kačák Mb of the Srbsko Fm, ?late T. kockelianus kockelianus Zone.

Distribution: type locality and bed only.

Discussion

Although the shell was not analysed for Si-content to prove the synapomorphy of Polycystina, its habitus and size strongly resembles those of numerous Sphaerellaria: polycystines with sphaerical siliceous shell perforated by densely-spaced pores. Accepting the hypothesis that tere are no true palaeactinommids, but that all Palaeozoic Sphaerellaria belong to entactiniids, the species is designed to Entactiniacea, with some doubt left, as the entactiniacean synapomorphy, the interior spicule, has not been proved in our material. Placing coronella to Entactiniidae is due to its (presumed) single shell and due (by inclusion) to its placement to Stigmosphaerostylus, by resemblance. Although several schemes of classification of Palaeozoic radiolarians were published (Nazarov 1975; Afanaseva #####; Won 1997), there is lack of a true phylogenetic study of Radiolaria to present sound hypothesis on relationships, and to postulate synapomorphies. Assignment to the taxon Stigmosphaerostylus is purely tentative for the same reason, and is provided just for conformance with ICZN/ICBN rules. The taxon Stigmosphaerostylus now contains all species formerly assigned to Entactinia, as Entactinia Foreman, 1963 is considered to be a younger synonym of Stigmosphaerostylus Hinde 1899 (see Aitchison and Stratford 1997).

Comparisons

There are similar individuals documented by Fang 2000###Pl. 1, fig 14-15. from the Yisak Group, Tibet,sample F716-4 (tentatively, based on ill-preserved radiolarians, attributed to Upper Devonian to Lower Carboniferous), assigned to Spongentactinia? sp. The figured individuals, although deformed, show similar habitus, are spineless, and possess ca 24 pores per circumference, but differ remarkably in size being 60 to 80 μm in diameter.

The individual, figured on Pl. 5 fig. 8 of Wang, Aitchison and Luo 2003, from the Famennian of West Yunnan and Guangxi, attributed there to species aranea Gourmelon1986 (Polyentactiniidae: Polyentactinia), is somewhat similar in pore habitus( possessing elevated pore wall) and count, but differs in presence of three-bladed spine, and small thorns on pore edges. However, other individuals attributed to this speciesdiffer substantially in having irregular, polygonal, rather than circular, pores that vary in size substantially.

The individuals on Pl. 5 figs. 16, 18, 19 of Wang, Aitchison and Luo 2003, from the Famennian of West Yunnan and Guangxi, attributed there to species minax Hinde, 1899 (Entactiniidae: Trilonche), is similar in pore habitus(possessing very regular pores with elevated pore wall) and count, but differs remarkably in presence of two three-bladed polar spines, and optional four rod-like equatorial spines. Also, it has a medullary shell, which was not ascertained in coronella, n.sp.

The same holds for the individual HKUDES 97/0202 figured on Pl. 6 fig. D of Aitchison et al 1999 from Frasnian of Bournes Lane, N of Tamworth, Gamilaroi Terrane, eastern Australia , attributed there to species ?hindea Hinde, 1899 (Entactiniidae: Trilonche),

The individual HKUDES 97/0176 figured on Pl. 4 fig. P of Aitchison et al 1999 from Givetian of Glenrock Station, , Gamilaroi Terrane, eastern Australia , marked as 'Entactiniid gen et sp. indet ' is similar in pore habitus(possessing very regular pores with elevated pore wall) and count, but differs remarkably in presence of six robust three-bladed spines.

The individuals HKUDES 97/0119 and B AMF 96723, figured on Pl. 1 figT, and PL. 4, fig. T of Aitchison et al 1999, respectively, from Emsian and Givetian of the Gamilaroi Terrane, eastern Australia ,attributed there to species B (Entactiniidae: Stigmosphaerostylus), is similar in pore habitus(possessing very regular pores with elevated pore wall) and count, but differs remarkably in presence of six three-bladed spines.

The individual FF-P001/115-09211, figured on text-fig2, fig. d of Afanasieva 2000## from middle Frasnian of Ukhtinskaya-3B borehole, Russia, assigned to species bogdanovi Afanasieva 2000(Entactiniidae: Entactinia = Stigmosphaerostylus) is similar in pore habitus (possessing very regular pores with elevated pore wall) and count, but differs remarkably in presence of six robust three-bladed spines, and in substantially smaller size (70 μm sphere diameter).

The individual USNM 485973, figured on Pl. 1 fig D, of Boundy-Sanders et al. 1999, from late Frasnian of Roberts Mountains, Nevada, marked as 'Entactiniid - possibly Entactinia or Entactinosphaera' is similar in pore habitus (possessing very regular pores with elevated pore wall) and count, but differs in presence of one robust three-bladed spine, several small rod-like spines, and in substantially smaller size.

The individuals figured on Pl. 1 fig 1-4, 18, of Won 1997a, from the Frasnian of Pillara Range, Canning Basin, Western Australia, assigned to species octaradiata Won 1997:349 (Entactiniidae: Entactinia = Stigmosphaerostylus), are similar in pore habitus (possessing very regular pores with elevated pore wall with small thorns on pore triple-points) and count, but differs remarkably in having more equally-sized pores, in presence of numerous rod-like, long spines of different lengths, and in presence of microsepta. The individuals figured on Pl. 1 fig 5-7, 13, 14, 17, of Won 1997a, from the Frasnian of Pillara Range, Canning Basin, Western Australia, assigned to species sexradiata Won 1997:348 (Entactiniidae: Entactinia = Stigmosphaerostylus), are similar in pore habitus (possessing very regular pores with elevated pore wall with small thorns on pore triple-points) and count, but differs remarkably in having more equally-sized pores, in presence of numerous rod-like, long spines of different lengths, and in presence of microsepta.

The individuals figured on Pl. 1 fig 1-2, 4, of Won 1997b, from the Frasnian of Pillara Range, Canning Basin, Western Australia, assigned to species elegans Won 1997b (Entactiniidae: Retentactiniinae: Apophysisphaera), are similar in pore habitus (possessing very regular pores with elevated pore wall with small thorns on pore walls, not always on triple-points) and count, but differs remarkably in having more equally-sized pores, in presence of six rod-like, long spines with apophyses, and in presence of microsepta.

Conclusions



1. Although abundant radiolarian cross-sections were previously reported by several authors (Wähner, 1917; Petránek, 1946; Chlupáč 1960; Chlupáč et al., 1992; Budil, 1995), it took some effort to isolate a single 3D-preserved radiolarian from the Kačák Mb. of Bohemia.

2. This occurrence constitutes a new species, coronella, n. sp. (Entactiniidae: Stigmosphaerostylus) [= Stigmosphaerostylus coronella, n.sp. according to ICZN/ICBN rules].

3. This species markedly differs from anything being known up to now from the preceding Choteč Fm. (Cejchan 1987, Braun-Budil####, Cejchan,in prep. ), being (supposedly) completely spineless, and possessing very regular, big pores with elevated pore walls.

4. The rarity of radiolarians in dark limestone nodules from the early Kačák Mb. compared to just slightly earlier Choteč limestone is striking, as deepening of the basin is presumed with the otomari-Event. The rarity of radiolarians is not, in this case, caused by diagenetic processes in the limestone, as the radiolarian shell found is well preserved. Maybe that thin beds and nodules of pelbiodetrital limestones in the Kačák Mb. represent a quick (re)sedimentation from the shallower parts of the Prague basin (Budil, 1995). the same scarcity was recently observed within pelbiodetrital limestones of the Chotec Fm., supposedly resedimented from the shallow water crinoidal debris.



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Čejchan, P. ###,

Acknowledgments

The work has been supported by GAČR grant #205/03/1124, and by #####. Thanks are due to A. Langrová, Z. Korbelová, and V. Böhmová for SEM photagraphy. Figure captions Fig. 1 Stratigraphic correlation of several localities where Kačák Mb is exposed. Compiled from Budil 1995. 1- massive biomicritic limestones; 2 - thin-bedded biomicritic limestones; 3- fibne boidetritic limestones; 4 - coarse biodetrital limestones; 5 - lithoclastic breccia; 6 - dark calcareous claystones and clayey limestones; 7 - thin-bedded cherts; 8- calcareous siltstones and biodetritic limestones with silt; 9 - siltstones; 10 - biolithic limestones; 11 - nodular cherts. Fig. 2 Stratigraphic table of the Eifelian stage in the Barrandian. Fig. 3 Phylogenetic "tree of life", a synthesis based on Cavalier-Smith 1998a; Stechmann & Cavalier-Smith 2002, 2003; López-Garcia 2002; Cavalier-Smith-IJSEM-2003; Cavalier-Smith & Chao, 2003; Nikolaev et al 2004. Not to scale. The cenancestor is indicated by an arrow at the root of the tree. Position of Polycystina is highlighted black, while polyphyletic Actinopoda are shown highlighted gray. Isochrones show presumed times before present, thus the main part of the diagram is occupied by the late Neoproterozoic time when the "eukaryan explosion", i.e, rapid radiation of Eukarya after melting of Varangerian snowball Earth about 580 million years ago, took part. Note that Archaea are sisters of Eukarya, and there is no Bacteria clade - either it would be identical to whole life (Biota), or, otherwise, become a paraphyletic group. Instead, "bacterial" clades are shown as the early branching groups.

Explanation of plates

Pl. 1

Fig. 1. coronella (?Stigmosphaerostylus, Polycystinea, Eukarya), sample PAC-SMP-16, Hostim (Beroun, CZ), specimen LHC-#####. Shell showing almost precisely circular pores of varying diameter. Scale bar ### . Stereopair.

Fig. 2. the same specimen, detail of pore surrounded by wall and projections forming a crown-like body.Scale bar ### . Stereopair.

Fig. 3. unidentified Polygnathus (Conodonta, Chordata, Metazoa), sample PAC-SMP-16, Hostim (Beroun, CZ), specimen LHC-#####. Scale bar ### . Stereopair.

Fig. 4 hexactin of an unidentified hexactinellid sponge (Hexactinellida, Porifera, Metazoa), sample PAC-SMP-16, Hostim (Beroun, CZ), specimen LHC-#####. Scale bar ### . Stereopair.