tournaisian (lower mississippian) bryozoans from belgium · tournaisian (lower mississippian)...

Tournaisian (Lower Mississippian) bryozoans from Belgium

Zoya Tolokonnikova, Andrej Ernst, and Edouard Poty

With 9 figures

Abstract: Ten bryozoan species are described from the Tournaisian of Namur-Dinant Basin, Belgium. Five species are new: Leptotrypa hexagona sp. nov., Dyscritella ornata sp. nov., Saffordotaxis spini-gerus sp. nov., Paranicklesopora ornaisa sp. nov., and Spinofenestella nodosa sp. nov. One species Rectifenestella rudis (Ulrich, 1890) is characterised by wide geographical and stratigraphical distri-bution. Four species are described in open nomenclature: Fistulipora sp. 1, F. sp. 2, Nikiforovella sp., Trepostomata sp. indet. The bryozoan assemblage of Belgium shows palaeogeographical connections with Tournaisian assemblages from some regions of Eurasia and USA.

Key words: Tournaisian, Belgium, Bryozoa, taxonomy, palaeobiogeography.

1. Introduction

The Tournaisian as a stratigraphic unit has been estab-lished originally in southern Belgium (DUmont 1832). At present, significant knowledge about geology and palaeontology of the investigated area, which became classical in the study of the Carboniferous deposits, has been gathered. Diverse marine fauna were described here, among them foraminifers, conodonts and rugose corals are important for regional and international bi-ostratigraphy (e.g., conil 1968; conil et al. 1991; Poty 1981; Groessens 1975; Webster & Groessens 1991; Poty et al. 2006, 2011, 2014). Miospore assemblages are also used for division of the basal Tournaisian de-posits (hiGGs et al. 1992). However, in various cases the mentioned groups of fossils cannot be helpful for inter-regional correlation because of their insufficient study or due to different facies in other regions. Therefore, the knowledge about other groups is also necessary.

Tournaisian deposits of southern Belgium are rich in macrofossils: brachiopods, corals, bryozoans, cri-noids, gastropods etc. Bryozoans represent a group of benthic marine animals with a significant potential for application in various fields of palaeoecology and bi-ostratigraphy (e.g., bancroft 1987; smith 1995; tay-

lor & allison 1998; taylor & James 2013). During the Carboniferous, bryozoans were diverse and widely distributed (ross 1981, ernst 2013, tolokonnikova et al. 2014). Bryozoan faunas are well studied in various parts of the world.

The existing knowledge of Tournaisian bryozoans of southern Belgium is very scarce. Some two dozens of fenestrate and cryptostome species were described by De koninck (1842-1844), Demanet (1923, 1938), and kaisin (1942). The majority of these species remain inadequately characterized because the descriptions were made on the external colony shape. No informa-tion about the internal morphology was provided by earlier authors, which is tremendously important for the provision of detailed and accurate systematic treat-ments and taxonomic identifications.

Analysis of facies with bryozoans from Waulsor-tian buildups of Tournaisian age in southern Belgium has been done by lees (1988, 2006) and Wyse Jackson (2006), while mckinney et al. (1987) have examined the role of fenestrate bryozoans as sediment bafflers in these buildups.

The aim of the present paper is the description of bryozoan assemblages from several formations of the Lower Tournaisian (Hastarian) and the lower part of the

©2015 E. Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany www.schweizerbart.de

DOI: 10.1127/njgpa/2015/0515 0077-7749/2015/0515 $ 5.75

N. Jb. Geol. Paläont. Abh. 278/1 (2015), 23–45 ArticleStuttgart, October 2015E

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24 Zoya Tolokonnikova et al.

Fig. 1. A – Schematic map with bryozoan localities in Belgium. B – field photographs from selected localities.

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Tournaisian (Lower Mississippian) bryozoans from Belgium 25

Upper Tournaisian (Ivorian) of the Namur-Dinant Basin and their comparison with contemporaneous faunas of different parts of the world.

2. Materials and methodsMaterial for study comes from the Namur-Dinant Basin (Fig. 1A). Part of the studied material was collected by the authors in 2013 from the Anseremme railway cutting (bed 239: N 50°14.466, E 04°54.683), Nutons quarry (interval of beds 115-116: N 50°19.737, E 04°59.004, and interval of beds 118-125: N 50°19.737, E 04°59.004 ), and Les Ornais quarry (beds 4-1, 4-2, and 4-3: N 50°27.033, E 05°17.750’). From these samples 61 thin sections were prepared. The study has been complemented by collections of lithological and coral thin sections of eDoUarD Poty deposited in the collections of paleontology (Department of Geology) of the University of Liège (23 thin sections). These collections include thin

sections from cores of boreholes Rekkem-2 (Belgian Geo-logical Survey reference 96E76) (depths 190.1, 190.7, 191.1, 196.0, 197.9 and 199.9 m) and Bossuit K (Belgian Geological Survey 97E866) (depths 101.4, 105.3, and 124.25 m), as well as from rock samples from localities La Belle Roche quarry (bc 10, bc 3b; collected 2008) and Nutons quarry (bc 22, 25, 29; collected 2011; Yvoir Fm. base bc 2; collected 2012). At these localities, bryozoans were found in nodular, argil-laceous limestones. In the Les Ornais quarry bryozoans are locally abundant, associated with brachiopods and crinoids (Fig. 1B).

The investigated bryozoans were studied in thin sec-tions using a transmitted light binocular microscope. In to-tal 84 thin sections were studied. Morphological character terminology is adopted from anstey & Perry (1970) for trepostomes, haGeman (1993) for cryptostomes, and snyDer (1991) for fenestrates. All the studied material is housed at the Department of Geology of the University of Liège (pre-fix: ULg).

Fig. 2. Bryozoan distribution in the Tournaisian of the Namur-Dinant Basin.

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Fig. 3.

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3. Geological setting

The Tournaisian of southern Belgium is distributed on both sides of the Midi-Eifel fault zone in the Na-mur Synclinorium (part of the Brabant Parautochtone of hance et al. 1999) and in the Dinant Synclinorium (part of the Ardenne Allochtone of the same authors). These structural units were part of the Namur-Dinant Basin during the time of deposition, which is composed of different sedimentation areas (Poty 1997; hance et al. 2001). The studied localities belong to the Dinant sedimentation area (Anseremme railway cutting), the Condroz sedimentation area (Nutons, Les Ornais and La Belle Roche quarries) and the eastern part of the Hainaut sedimentation area (Rekkem-2 and Bossuit K boreholes). About the stratigraphical position of the samples studied here, there are no significant differenc-es between these sedimentation areas and they can be positioned in the same lithostratigraphical scale (Fig. 2). The chrono, bio and sequence stratigraphical scales used here are those of Poty et al. (2014).

4. Systematic palaeontology

Phylum Bryozoa ehrenberG, 1831Class Stenolaemata borG, 1926

Superorder Palaeostomata ma et al., 2014Order Cystoporata astrova, 1964

Suborder Fistuliporina astrova, 1964Family Fistuliporidae Ulrich, 1882

Genus Fistulipora m’coy, 1849

Type species: Fistulipora minor m‘coy, 1849. Carbonifer-ous; England.

Diagnosis: Massive, encrusting, or branched colonies. Cylin-drical autozooecia with thin walls and complete diaphragms. Apertures rounded, with horseshoe-shaped lunaria. Autozo-oecia separated by extrazooidal vesicular skeleton. Maculae often developed.

Comparison: Fistulipora m‘coy, 1849 differs from Eri-dopora Ulrich, 1882 in having rounded, horseshoe-shaped lunaria instead of triangular ones. Furthermore, Eridopora develops persistently encrusting colonies, whereas Fistuli-pora may also develop massive and branched colonies.

Stratigraphical and geographical ranges: Ordovician to Permian; worldwide.

Fistulipora sp. 1Fig. 3A-D; Appendix

Material: ULg 7-7a-e.

Description: Encrusting colonies, 0.48 to 1.17 mm in thick-ness. Autozooecia growing from thick epitheca, bending sharply at their bases towards colony surface. Autozooecial apertures circular to oval. Basal diaphragms common, thin, horizontal or inclined. Lunaria well developed, triangular to horseshoe shaped. Vesicles moderate in size, separating autozooecia in 1-2 rows, polygonal in tangential section, box-like to hemispheric, with plane or slightly concave roofs, 8-9 arranged around each autozooecial aperture. Autozooecial walls thick, laminated.

Comparison: The present species is similar to Fistulipo-ra usitata GorJUnova & morozova, 1979 from the upper Tournaisian-Viséan of Mongolia having similar arrange-ment of vesicles and close aperture widths (0.18-0.32 mm vs. 0.22-0.34 mm in F. usitata). The present species is also similar to Fistulipora djeskazganica nekhoroshev, 1953 from the upper Tournaisian of Kazakhstan, but differs from it by smaller apertures (0.18-0.32 mm vs. 0.30-0.33 mm in F. djeskazganica).

Stratigraphical and geographical ranges: Hastière and Pont-d’Arcole Formations, Hastarian substage, Tournaisian, Mississippian; Anseremme cut, Belgium.

Fistulipora sp. 2Fig. 3E-F; Appendix

Material: ULg 6-1a (only tangential section).

Description: Encrusting colony, thickness unknown. Au-tozooecia growing from thick epitheca, bending sharply at their bases towards colony surface. Autozooecial apertures circular to oval. Basal diaphragms common, thin, horizon-tal or inclined. Lunaria poorly developed, horseshoe shaped. Vesicles moderate in size, separating autozooecia in 1-2 rows, polygonal in tangential section, box-like to hemispheric, with plane or slightly concave roofs, 8-9 arranged around each autozooecial aperture. Autozooecial walls thick, laminated.

Comparison: The present specimen differs from Fistulipora tubulosa nikiforova, 1933 from the Lower Carboniferous of Turkmenistan in smaller autozooecial apertures (0.19-0.25

Fig. 3. A-D – Fistulipora sp. 1. A – Tangential section showing autozooecia and vesicles, ULg 7-7a. B – Tangential section showing lunaria, ULg 7-7a. C – Longitudinal section, ULg 7-7a. D – Longitudinal section, ULg 7-7c. E-F – Fistulipora sp. 2. E – Tangential section showing autozooecia and vesicles. F – Tangential section, ULg 6-1a.

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mm vs. averagely 0.30 mm in F. tubulosa). It is also similar to the species Fistulipora aff. incrustans (PhilliPs, 1836) described by nekhoroshev (1953) from the upper Tournai-sian of Kazakhstan. The two species have thin encrusting colonies, 1-2 rows of vesicles between apertures and similar autozooecial width (0.19-0.25 mm vs. 0.21-0.27 mm in F. aff. incrustans). However, the original species Fistulipora incrustans (PhilliPs, 1836) has significantly larger autozo-oecial apertures (0.27-0.40 mm). Unfortunately, the material of nekhoroshev (1953) was studied externally, without thin sections, so its internal morphology is unknown.

Stratigraphical and geographical ranges: Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississip-pian; Nutons quarry, Belgium.

Order Trepostomata Ulrich, 1882

Suborder Amplexoporina astrova, 1965Family Atactotoechidae DUncan, 1939

Genus Leptotrypa Ulrich, 1883[= Calacanthopora DUncan, 1939]

Type species: Leptotrypa minima Ulrich, 1883. Cincinna-tian (Upper Ordovician); North America.

Diagnosis: Thin encrusting colonies. Autozooecia with po-lygonal apertures. Autozooecial walls irregularly thickened throughout the colony or near the periphery, indistinctly laminated, usually integrated in initial parts and merged near the colony surface. Autozooecial diaphragms absent or rare. Exilazooecia rare to common. Acanthostyles small to moderately large, common to abundant (modified after astrova, 1978).

Comparison: Leptotrypa Ulrich, 1883 differs from Anom-alotoechus DUncan, 1939 in having thin encrusting colony and rare diaphragms.

Stratigraphical and geographical ranges: Middle Ordovi-cian to Middle Carboniferous; worldwide.

Leptotrypa hexagona sp. nov.Fig. 4A-D; Appendix

Etymology: The species name refers to regular hexagonal shape of apertures.

Holotype: ULg 7-7b.

Paratypes: ULg 7-7c-e.

Type locality: Anseremme cut, Belgium.

Type horizon: Pont-d’Arcole Formation, Hastarian substage, Tournaisian, Mississippian.

Diagnosis: Encrusting colonies; autozooecial apertures po-lygonal; exilazooecia rare; 3-6 acanthostyles surrounding each autozooecial aperture; maculae consisting of macro-zooecia.

Description: Encrusting colonies, 0.48-0.72 mm in thick-ness. Autozooecia budding from a thin epitheca, growing a short distance parallel to the substrate, then bending sharply to the colony surface. Autozooecial apertures hexagonal. Ex-ilazooecia rare, 0.050-0.065 mm in diameter. Acanthostyles common, 3-6 surrounding each autozooecial aperture. Au-tozooecial walls finely laminated, 0.010-0.015 mm thick in endozone; laminated, merged without visible autozooecial boundaries, 0.06-0.08 mm thick in exozone. Maculae con-sisting of macrozooecia, 0.7-1.0 mm in diameter. Macrozo-oecial apertures 0.26-0.29 mm in diameter, spaced 0.36-0.41 mm from centre to centre.

Comparison: Leptotrypa hexagona sp. nov. differs from L. fistulosa lavrentJeva, 1970 by thicker colonies (0.48-0.72 mm vs. 0.25-0.35 mm in L. fistulosa), thicker autozooecial walls in exozone (0.06-0.08 mm vs. 0.04 mm in L. fistulosa), larger acanthostyles ( 0.03-0.06 mm vs. 0.02-0.03 mm in L. fistulosa), as well as by rare exilazooecia.

Stratigraphical and geographical ranges: Pont-d’Arcole Formation, Hastarian substage, Tournaisian, Mississippian; Anseremme cut, Belgium.

Family Dyscritellidae DUnaeva & morozova, 1967Genus Dyscritella Girty, 1911

Type species: Dyscritella robusta Girty, 1911. Mississippian (Lower Carboniferous); Arkansas, USA.

Diagnosis: Dendroid and encrusting colony with abundant acanthostyles and exilazooecia. Autozooecia parallel to longitudinal direction of the colony in endozone; gradually bending outward in exozone. Diaphragms in autozooecia lacking or very rare; lacking in exilazooecia. Exilazooecia circular to angular in cross section and separated from the autozooecia and from each other by thick walls. Two sizes of acanthostyles may be present. Zooecial walls thin in en-dozone, rapidly thickening in the exozone (modified after ernst & GorGiJ 2013).

Comparison: Dyscritella Girty, 1911 generally lacks dia-phragms which are commonly developed in the similar

Fig. 4. A-D – Leptotrypa hexagona sp. nov. A-B – tangential section, ULg 7-7b. C-D – Longitudinal section, paratype ULg 7-7c. E-G – Dyscritella ornata sp. nov., holotype ULg 6-2b. E-F – Tangential section. G – Longitudinal section.

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Fig. 4.

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genus Dyscritellina morozova in DUnaeva & morozova, 1967. Furthermore, Dyscritellina has extremely large acan-thostyles, which are absent in Dyscritella.

Stratigraphical and geographical ranges: Devonian to Triassic; worldwide.

Dyscritella ornata sp. nov.Figs. 4E-G, 5A-C; Appendix

Etymology: The species name refers to abundant exilazooe-cia which produce an ornamentation on the colony surface.

Holotype: ULg 6-2b.

Paratypes: ULg 4-3a-1, 4-3a-6, 6-2e, i, 7-7e.

Type locality: Nutons quarry, Belgium.

Type horizon: Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississippian.

Diagnosis: Encrusting and branched colonies with moder-ately wide exozones; autozooecial diaphragms absent; ex-ilazooecia abundant, 3-10 surrounding each autozooecial aperture; acanthostyles common, 2-8 surrounding each auto-zooecial aperture; autozooecial walls laminated, moderately thick in exozone; maculae not observed.

Description: Encrusting and branched colonies Encrust-ing colonies 0.26-0.66 mm in thickness. Branched colonies 0.75-1.00 mm in diameter, with 0.18-0.26 mm wide exozones and 0.39-0.48 mm wide endozones. Autozooecia budding from a thin epitheca, growing a short distance parallel to the substrate, then bending sharply to the colony surface. In a branched colony autozooecia diverging at low angles in exozone. Autozooecial diaphragms absent. Autozooecial apertures polygonal. Exilazooecia abundant, 3-10 surround-ing each autozooecial aperture, originating at the base of exozone. Acanthostyles common, 2-8 surrounding each au-tozooecial aperture. Autozooecial walls finely laminated, 0.010-0.015 mm thick in endozone; laminated, merged with-out visible autozooecial boundaries, 0.020-0.045 mm thick in exozone. Maculae not observed.

Comparison: Dyscritella ornata sp. nov. differs from D. clara (trizna, 1958) from the upper Tournaisian of Kuznets Basin by absence of diaphragms, thinner branched colonies (branch diameter 0.75-1.00 mm vs. 3.3 mm in D. clara), smaller apertures (autozooecial width 0.09-0.18 mm vs. 0.16-0.24 mm in D. clara), and by more abundant and smaller acanthostyles (2-8 vs. 3-4 acanthostyles around each auto-

zooecial aperture in D. clara; acanthostyle diameter 0.015-0.060 mm vs. 0.06-0.08 mm in D. clara).

Stratigraphical and geographical ranges: Pont-d’Arcole Formation, Hastarian substage, Tournaisian, Mississippian; Anseremme cut and Les Ornais quarry; Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississip-pian; Nutons quarry, Belgium.

Incertae sedisFamily uncertainGenus uncertain

Trepostomata sp. indet.Figs. 5D-H, 6A; Appendix

Material: Single colony ULg 4-2a-(1-4).

Description: Branched colony, 4.45-4.85 mm in diameter, with 0.36-0.40 mm wide exozones and 3.73-4.05 mm wide endozones. Autozooecial apertures oval. Autozooecial di-aphragms common to abundant in the transition between endozone and exozone, straight, thin. Autozooecial walls laminated, 0.03-0.05 mm thick in endozone; with serrated dark zooecial boundaries at the base of exozone and merged in the outer part of exozone, 0.11-0.14 mm thick in exozone. Acanthostyles and exilazooecia rare. Heterostyles common, arranged in 1-3 irregular rows between autozooecia, 0.013-0.020 mm in diameter. Maculae not observed.

Comparison: The present material does not fit completely to any known genus. Acanthostyles, abundant heterostyles and merged autozooecial walls make it similar to some species of the genus Stenophragmidium bassler, 1952 (cleary & Wyse Jackson 2007). However, species of Stenophragmidium possess hemiphragms. The heterostyles resemble paurostyles (simple styles without laminated core sensu blake (1983)). Similar styles occur in the genus Boardmanella GorJUnova & Weis, 2003. However, Boardmanella possesses variously sized paurostyles and no true acanthostyles. Furthermore, the autozooecial wall in Boardmanella is uniformly merged, whereas the walls in the present material are serrated in the basal part of exozone. The heterostyles in the present mate-rial can be also interpreted as tubules which occur in eri-dotrypellid bryozoans, such as Eridotrypella DUncan, 1939. However, tubules in eridotrypellids are usually smaller, and these bryozoans have merged autozooecial walls with lami-nated singulum.

Stratigraphical and geographical ranges: Yvoir Forma-tion (Basal Hun Member), Hastarian substage, Tournaisian, Mississippian; Les Ornais quarry, Belgium.

Fig. 5. A-C – Dyscritella ornata sp. nov., paratype ULg 6-2i. A – Tangential section. B – Longitudinal section. C – Tangential section showing exilazooecia and acanthostyles. D-H – Trepostomata sp. indet. D-E – Branch transverse section, ULg 4-2a-1. F – Longitudinal section, ULg 4-2a-2. G-H – Tangential section showing acanthostyles (arrow) and paurostyles, ULg 4-2a-4.

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Fig. 5.

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Order Cryptostomata vine, 1884Suborder Rhabdomesina astrova & morozova, 1956

Family Nikiforovellidae GorJUnova, 1975Genus Nikiforovella nekhoroshev, 1948

Type species: Nikiforovella alternata nekhoroshev, 1948, by original designation. Mississippian (Lower Carbonifer-ous); Altai, Russia.

Diagnosis: Branched colonies. Autozooecia diverging at low angles from distinct median axis. Hemisepta absent, diaphragms rare. Autozooecial walls laminated, with dark zooecial boundaries. Metazooecia few between longitudi-nally successive autozooecial apertures; acanthostyles com-mon to abundant. Longitudinal ridges absent.

Comparison: Nikiforovella nekhoroshev, 1948 is similar to Streblotrypella nikiforova, 1948, but differs from it mainly in the shape of autozooecia, which bend at higher angles in exozone, and in the absence of longitudinal ridges. Moreover, styles can be absent in Streblotrypella.

Stratigraphical and geographical ranges: Devonian to Permian; worldwide.

Nikiforovella sp.Fig. 6B-E; Appendix

Material: ULg Bossuit K/124.25; Nutons 2011, bc 25. Description: Branched colonies, 0.8-1.9 mm in diameter, with 0.15-0.40 mm wide exozones and 0.5-1.1 mm wide endozones. Autozooecia growing in spiral pattern from the median axis, rhombic in the transverse section of endozone, abruptly bending in exozone. Autozooecial apertures oval to circular, arranged in regular diagonal rows. Autozooecial diaphragms absent. Metazooecia originating at the base of exozone, 2-3 arranged between longitudinally successive autozooecial apertures. Acanthostyles 0.02-0.025 mm in diameter, 4-5 arranged between longitudinally successive autozooecial apertures, having distinct hyaline cores and laminated sheaths. Autozooecial walls granular, 0.005-0.008 mm thick in endozone; finely laminated, without visible zo-oecial boundaries in exozone.

Comparison: The present material differs from Nikiforov-ella kasakhstanica nekhoroshev, 1948 from Tournaisian of Kazakhstan in smaller acanthostyles (0.02-0.025 mm vs. 0.05 mm in N. kasakhstanica). The present species is also similar to Nikiforovella alternata nekhoroshev, 1956 from

the lower Tournaisian of Kazakhstan, but differs from it by larger metazooecia (0.03-0.07 mm vs. 0.020-0.025 mm in N. alternata), and more acanthostyles arranged between lon-gitudinally successive apertures (4-5 vs. 2 in N. alternata).

Stratigraphical and geographical ranges: Upper Member of the Hastière Formation, Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississippian; Nutons quarry, Belgium. Hastière Formation, Hastarian substage, Tournaisian, Mississippian; Bossuit K borehole, Belgium.

Family Rhomboporidae simPson, 1895Genus Saffordotaxis bassler, 1952

Type species: Rhombopora incrassata Ulrich, 1890. Lower Mississippian; USA (Kentucky).

Diagnosis: Branched colonies with distinct linear axis. En-dozones and exozones distinctly separated. Autozooecia with oval apertures and regularly thickened walls in the exozone, diverging at angles of 20-30° from the axis, bending sharply in exozones and intersecting the colony surface at angles of 80-90°; polygonal in endozone becoming hexagonal and rounded at colony surface. Longitudinal arrangement of au-tozooecia regular. Diaphragms complete, rare. Hemisepta absent. Metazooecia and acanthostyles absent. Aktinoto-styles common to abundant, arranged in single or multiple rows, arising in the exozone.

Comparison: Saffordotaxis bassler, 1952 differs from Pri-morella romantchUk & kiseleva, 1968 in shape of autozo-oecia with sharp bend in the exozone.

Stratigraphical and geographical ranges: Middle Devo-nian to Lower Permian; worldwide.

Saffordotaxis spinigerus sp. nov.Figs. 6F-I, 7A; Appendix

Etymology: The species name refers to large aktinotostyles (from Latin “spiniger” – spiny).

Holotype: ULg 4-1b-1

Paratypes: ULg Rekkem-2 (depths 196.0, 199.9, 191.1, 197.9, 190.7, 190.1 m); Bossuit K (depths 101.4, 105.3 m); La Belle Roche quarry 2008, bc 10, bc 3b; Nutons 2011 – bc 29; Nu-tons quarry 2012 - Yvoir Fm. base bc 2; ULg 4-3a-(1, 3, 5-6), 4-3e-(1-2, 5-6), 4-3d-(1-2, 4), 4-3b-(1-4, 6), 4-3c-(1-2), 4-1d-(1-2), 4-1b-2; ULg 6-2c, d, g, h, j, k, m, n, o.

Fig. 6. A – Trepostomata sp. indet., ULg 4-2a-2. A – Longitudinal section. B-E – Nikiforovella sp., ULg Bossuit KUL/124.25. B-D – Longitudinal section. E – Tangential section showing autozooecial apertures, metazooecia and acanthostyles. F-I – Saffordotaxis spinigerus sp. nov. F-G – Longitudinal section, ULg 4-1b-1. H – Tangential section, holotype ULg 4-1b-1. I – Tangential section, paratype ULg 4-3a-6.

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Fig. 6.

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Type locality: Les Ornais quarry, Belgium.


Diagnosis: Thin branched colonies with narrow exozones; autozooecia budding at angles of 21–37° in endozones, abruptly bending in exozones; rhombic, tear-drop shaped in transverse section of endozone; autozooecial apertures oval, arranged in regular diagonal rows on branches; large aktino-tostyles in a single row between autozooecia.

Description: Branched colonies, 0.7-1.0 mm in diameter, with 0.15-0.40 mm wide endozones and 0.22-0.41 mm wide exozones. Autozooecia tubular, growing in spiral pattern from the distinct median axis at angles of 21–37° in en-dozones, abruptly bending in exozones; having a rhombic, tear-drop shape in transverse section of endozone. Autozo-oecial apertures oval, arranged in regular diagonal rows on branches. Autozooecia diaphragms occasionally present. Aktinotostyles large, arranged in a single row between au-tozooecia. Autozooecial walls finely laminated, with dark di-viding layer, 0.005-0.008 mm thick in endozone; laminated, without distinct boundaries in exozone.

Comparison: Saffordotaxis spinigerus sp. nov. differs from S. germanа ariUnchimeG, 2005 from the Viséan of Mon-golia by smaller apertures (0.07-0.11 mm vs. 0.14 mm in S. germanа), by size and location of aktinotostyles (0.04-0.07 mm in a single row vs. 0.02 mm in several rows or irregularly in S. germanа), and by presence of diaphragms.

Stratigraphical and geographical ranges: Pont d’Arcole Formation, Hastarian substage, Tournaisian, Mississippian; Bossuit K borehole, Belgium. Orient Formation, Upper Has-tarian substage, Tournaisian, Mississippian; Rekkem-2 bore-hole, Belgium. Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississippian; Nutons and Les Or-nais quarries, Belgium. Ourthe Formation, Ivorian substage, Tournaisian, Mississippian; La Belle Roche quarry, Belgium.

Family Goldfussitrypidae GorJUnova, 1985Genus Paranicklesopora GorJUnova, 1988

Type species: Paranicklesopora elenae GorJUnova, 1988. Mississippian (Viséan); Mongolia.

Diagnosis: Branched colonies. Autozooecia diverging at low angles in endozone, often forming a central bundle. Superior and inferior hemisepta present. Autozooecial diaphragms rare. Autozooecial walls laminated, with dark zooecial

boundaries. Metazooecia absent. Acanthostyles and/or pau-rostyles present, forming a regular pattern around autozo-oecial apertures.

Comparison: Paranicklesopora GorJUnova, 1988 differs from Nicklesopora bassler, 1952 by the presence of superior and inferior hemisepta and acanthostyles.

Stratigraphical and geographical ranges: Mississippian; Mongolia, Transcaucasia, Europe. Kuznets Basin.

Paranicklesopora ornaisa sp. nov.Figs. 7B-G, 8A-B; Appendix

Etymology: The species name refers to name of Les Ornais quarry where it was found.

Holotype: ULg 4-3d-2.

Paratypes: ULg 4-3b-6, 4-3a-5, 4-1d-(1-2), 4-1b-1, 4-3a-(1-3, 5-6), 4-1c-1, 4-1e-4, 4-3d-(1, 3).


Type horizon: Yvoir Fm. (Hun Member), Hastarian sub-stage, Tournaisian, Mississippian.

Diagnosis: Thin branched colonies with narrow endozones and occasional secondary overgrowths; autozooecia tubular, growing from a central bundle of zooecia, abruptly bending in exozones; superior hemisepta long, hook-shaped, curved proximally; inferior hemisepta long, situated beneath supe-rior hemisepta; acanthostyles and paurostyles abundant.

Description: Branched colonies, 0.70-1.35 mm in diameter, with 0.27-0.91 mm wide endozones and 0.14-0.28 mm wide exozones. Secondary overgrowths occurring, 0.24-0.28 mm thick. Autozooecia tubular, growing from a central bundle of zooecia, abruptly bending in exozones, having polygonal shape in transverse section of endozone. Superior hemisepta long, hook-shaped, curved proximally; inferior hemisepta long, situated beneath superior hemisepta. Autozooecial ap-ertures oval, arranged in regular diagonal rows on branches. Acanthostyles having hyaline cores and laminated sheaths, abundant, arranged in 1-3 rows between autozooecia. Pauro-styles scattered between acanthostyles. Autozooecial walls finely laminated, 0.001-0.005 mm thick in endozone; lami-nated, with dark dividing layer in exozones.

Comparison: Paranicklesopora ornaisa sp. nov. differs from P. stupenda GorJUnova in GorJUnova & lavrentJeva,

Fig. 7. A – Saffordotaxis spinigerus sp. nov., paratype ULg 4-3a-7. A – Branch transverse section. B-G – Paranicklesopora ornaisa sp. nov. B-C – Branch transverse section, paratype ULg 4-3a-3. D – Oblique sections, holotype ULg 4-3d-2. E-F – Tangential section showing autozooecial apertures, acanthostyles and paurostyles, holotype ULg 4-3d-2. G – Longitudinal section, holotype ULg 4-3d-2.

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Fig. 7.

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2007 from the Tournaisian of Azerbaijan in having a wider exozone (0.14-0.28 mm vs. 0.07-0.10 mm in Р. stupendа ), secondary overgrowths, and smaller autozooecial apertures (aperture width 0.04-0.07 mm vs. 0.07-0.08 mm). Further-more, Paranicklesopora ornaisa possesses acanthostyles 0.01-0.04 mm in diameter, which are arranged in 1-3 rows between autozooecial apertures, whereas aktinotostyles in P. stupenda are arranged irregularly on the colony surface. GorJUnova (in GorJUnova & lavrentJeva, 2007) gave the value by 2 µm (0.002 mm) for the aktinotostyle diameter in P. stupenda. However, this value appears to us not realistic, because it can be compared with diameter of paurostyles which are simple structureless styles (blake 1983). Pauro-styles in Paranicklesopora ornaisa sp. nov. are 0.001-0.005 mm in diameter.

Stratigraphical and geographical ranges: Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississip-pian; Les Ornais quarry, Belgium.

Order Fenestrata elias & conDra, 1957Suborder Fenestellina astrova & morozova, 1956

Family Fenestellidae kinG, 1849Genus Spinofenestella termier & termier, 1971

Type species: Fenestella spinulosa conDra, 1902 by subse-quent designation (morozova 1974). Upper Carboniferous, Coal Measure; Nebraska, USA.

Diagnosis: Zoarium fan-shaped or conical. Branches straight, connected by thin dissepiments. Two rows of auto-zooecia per branch, overlapped basally. Autozooecial cham-bers triangular in deep tangential section, oval right below the distal tube. Chambers circular in cross-section. Proximal hemisepta absent or poorly developed. Low keel with a single row of nodes on the observe surface.

Comparison: Alternifenestella termier & termier, 1971 is a synonym of Spinofenestella due to the close morphological similarities of their type species, according to haGeman & mckinney (2010), and GorJUnova & Weis (2012) retained Alternifenestella as a valid genus.

Stratigraphical and geographical ranges: Silurian to Up-per Permian; worldwide.

Spinofenestella nodosa sp. nov.Fig. 8C-H; Appendix

Etymology: The species name refers to abundant and di-verse nodes of the new species.

Holotype: ULg 4-1g-1.

Paratypes: ULg 4-1a-1, 4-3a-4.



Diagnosis: Reticulate colony with moderately coarse mesh-work; dissepiments narrow; fenestrules oval to rectangular; autozooecia in two rows on branches with occasional inser-tion of the third row before bifurcation; autozooecia triangu-lar to trapezoid in mid tangential section; axial wall between autozooecial rows strongly zigzag; hemisepta absent; aper-tures circular with a single node; 4-7 apertures per fenestrule length; keel low, with moderately large nodes; large nodes on the reverse colony surface.

Exterior description: Reticulate colony formed by straight branches joined by narrow dissepiments. Fenestrules oval to rectangular, long, narrow. Autozooecia arranged in two rows on branches. Occasionally three rows of apertures developed for the length of a fenestrule. Autozooecial apertures circu-lar, with low smooth peristome; 4 to 7 apertures spaced per fenestrule length. Single node developed at aperture, 0.02-0.03 mm in diameter. Moderately large elliptical nodes on the low keel, widely spaced. Irregularly arranged sharp nodes on the reverse side of branches.

Interior description: Autozooecia short, triangular to trapezoid in mid tangential section; with short vestibule in longitudinal section. Axial wall between autozooecial rows strongly zigzag; aperture positioned at distal end of chamber. Hemisepta absent. Internal granular skeleton thin, continu-ous with obverse keel, nodes, peristome and across dissepi-ments. Outer laminated skeleton thin. Abundant microstyles in the laminated skeleton, having distinct hyaline cores and dark laminated sheaths, 0.005-0.007 mm in diameter.

Comparison: Spinofenestella nodosa sp. nov. differs from S. undulata troizkaya, 1975 from the Kassinski Horizon (low-er Tournaisian) of Kazakhstan in thicker branches (0.36-0.62 mm vs. 0.25-0.30 mm in S. undulata) and larger fenestrules (0.23-0.60 х 0.78-1.73 mm vs. 0.25-0.31 x 0.63-0.73 mm in S. undulata). The new species differs from all Tournaisian species of Spinofenestella in having a larger number of ap-ertures per fenestrule and by development of large nodes on branches.

Fig. 8. A-B – Paranicklesopora ornaisa sp. nov. A – Longitudinal section, paratype ULg 4-1b-1. B – Longitudinal sec-tion (arrow – inferior hemiseptum), paratype ULg 4-3a-1. C-H – Spinofenestella nodosa sp. nov. C-D – Tangential section, holotype ULg 4-1g-1. E-H – Tangential section (G, apertural node – arrow), paratype ULg 4-1a-1. I – Rectifenestella rudis (Ulrich, 1890), ULg 6-2e. I – Tangential section.

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Fig. 8.

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Stratigraphical and geographical ranges: Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississip-pian; Les Ornais quarry, Belgium.

Genus Rectifenestella morozova, 1974

Type species: Fenestella medvedkensis schUlGa-nester-enko, 1951. Kasimovian (Upper Carboniferous); Russian Platform.

Diagnosis: Reticulate colonies consisting of fine to moder-ately robust branches and straight dissepiments. Autozooecia

triangular to pentagonal in mid-tangential section. Superior hemisepta present; inferior hemisepta absent. Narrow keel with one row of intermediate-sized nodes.

Comparison: Rectifenestella differs from Laxifenestella morozova, 1974 in the pentagonal shape of the autozooe-cia in mid-tangential section and in the absence of inferior hemisepta.

Stratigraphical and geographical ranges: Early Devonian to Late Permian; worldwide.

Fig. 9. A-E – Rectifenestella rudis (Ulrich, 1890). a-B – Tangential section showing branches, fenestrules, autozooecial chambers and apertures, ULg 6-2e. C – Mid-tangential section showing place of dichotomy, ULg 6-2e. D – Tangential section showing autozooecial aperture containing apertural nodes, ULg 6-2a. E – Branch transverse section showing autozooecial chambers and low keel, ULg 6-2a.

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Rectifenestella rudis (Ulrich, 1890)Figs. 8I, 9A-E; Appendix

1890 Fenestella rudis Ulrich, p. 537, pl. 49, fig. 3-3d.1926 Fenestella rudis Ulrich, 1890. – nekhoroshev, p.

1242, pl. 19, figs. 7-8, pl. 20, fig. 5.1927 Fenestella rudis Ulrich, 1890. – nikiforova, p. 178,

pl. 4, figs. 2, 3.1932 Fenestella rudis Ulrich, 1890. – nekhoroshev, p. 53,

pl. 2, fig. 2.1933 Fenestella rudis Ulrich, 1890. – nikiforova, p. 18,

pl. 4, figs. 11-13.1948 Fenestella rudis Ulrich, 1890. – nikiforova, p. 23,

pl. 6, fig. 3.1950 Fenestella rudis Ulrich, 1890. – nikiforova, p. 109,

pl. 2, fig. 1, pl. 9, fig. 2.1956 Fenestella rudis Ulrich, 1890. – nekhoroshev, p.

153, pl. 18, figs. 1, 3.1958 Fenestella rudis Ulrich, 1890. – trizna, p. 127, pl.

34, fig. 5, pl. 35, figs. 1-4.1973 Fenestella rudis Ulrich, 1890 multinodosa tavener-

smith, 1973. – tavener-smith, p. 424, pl. 6, figs. 1-7.1979 Rectifenestella rudis (Ulrich, 1890). – GorJUnova &

morozova, p. 55, pl. 16, fig. 2.1981 Rectifenestella rudis (Ulrich, 1890). – morozova, p.

63, pl. 14, fig. 5.1991 Cubifenestella rudis (Ulrich, 1890). – snyDer, p. 90,

pl. 29, figs. 1-11, pl. 30, figs. 1-7.1999 Rectifenestella rudis (Ulrich, 1890). – lU, p. 158, pl.

5, figs. 6-8.2000 Rectifenestella rudis (Ulrich, 1890). – PoPeko, p. 100,

pl. 6, fig. 2.

Material: ULg 6-2a, c, e, f, i.

Exterior description: Reticulate colony formed by straight branches joined by narrow dissepiments. Fenestrules oval to rectangular, long, narrow. Autozooecia arranged in two rows on branches, with an inclusion of a third row at the place of dichotomy. Autozooecial apertures circular, with low peristome containing small nodes; 4 to 5 apertures spaced per fenestrule length. Low keel with a single row of smaller nodes alternating with larger nodes. Smaller nodes 0.015-0.030 mm in diameter; larger nodes 0.05-0.07 mm in diameter. Longitudinal striation on reverse side of branches.

Interior description: Autozooecia short, pentagonal to roughly rectangular in mid tangential section; with short vestibule in longitudinal section. Axial wall between au-tozooecial rows strongly to weakly zigzag; aperture posi-tioned at distal end of chamber. Hemisepta absent. Internal granular skeleton thin, continuous with obverse keel, nodes, peristome and across dissepiments. Outer laminated skeleton thin. Abundant microstyles in the laminated skeleton, having distinct hyaline cores and dark laminated sheaths, 0.005-0.007 mm in diameter.

Comparison: Rectifenestella rudis (Ulrich, 1890) differs from R. cesteriensiformis (nekhoroshev, 1956) from the Vi-séan of Kazakhstan in longer fenestrules (0.78-0.95 mm vs. 0.60-0.65 mm in R. cesteriensiformis), and smaller apertures

(aperture width 0.08-0.11 mm vs. 0.14 mm in R. cesterien-siformis).

Stratigraphical and geographical ranges: Yvoir Formation (Hun Member), Hastarian substage, Tournaisian, Mississip-pian; Nutons quarry, Belgium. Viséan, USA, Tournaisian-Viséan, Eurasia.

5. Discussion

Ten bryozoan species occur in the Tournaisian of the Namur-Dinant Basin. The highest diversity is observed at the transition between the lower and upper Tournai-sian substages (Fig. 2). At the base of the Tournaisian (Hastière Formation) only one bryozoan species, Ni-kiforovella sp., was found. In the Pont-d’Arcole For-mation specific composition is very poor comprising four species: Fistulipora sp. 1, Leptotrypa hexagona sp. nov., Dyscritella ornata sp. nov., and Saffordotaxis spinigerus sp. nov. The species Saffordotaxis spini-gerus sp. nov. has wide stratigraphical distribution be-ing found in the Orient, Yvoir (Hastarian) and Ourthe Formations (Ivorian).

The species composition changes in the upper part of the Hastarian substage (Yvoir Formation, Hun Mem-ber). Besides the species Dyscritella ornata sp. nov. and Saffordotaxis spinigerus sp. nov. persisting from underlaying deposits, Fistulipora sp. 2, Paranickleso-pora ornaisa sp. nov., Spinofenestella nodosa sp. nov., Trepostomata sp. indet., Nikiforovella sp., and Rectifen-estella rudis (Ulrich, 1890) appear in the Hun Member of the Yvoir Formation.

The studied bryozoans are highly endemic at the species level. The only species known from previous studies, Rectifenestella rudis (Ulrich, 1890), displays wide stratigraphical and geographical distribution (Tournaisian-Viséan of USA, Kazakhstan, Uzbekistan, Eastern Transbaikalia, Northern Urals, Kuznets Basin, Mongolia, China, Ireland, Germany, as well as Serpuk-hovian of northeastern Russia). These records certainly need to be revaluated; however, such an investigation has not been done yet.

All genera of the studied association except Para-nicklesopora are cosmopolitan, known from Ordovi-cian/Devonian to Carboniferous/Permian. The genus Paranicklesopora was previously known from the Mississippian of Eurasia (Mongolia and Azerbaijan). Bryozoans of the genera identified in the Tournaisian of Belgium, are known from the Tournaisian deposits of Kuznets Basin (Fistulipora, Nikiforovella, Para-nicklesopora, Rectifenestella), Kazakhstan (Fistulipo-ra, Nikiforovella, Spinofenestella), China (Fistulipora,

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Saffordotaxis, Rectifenestella), Mongolia (Nikiforovel-la, Rectifenestella), USA (Fistulipora, Rectifenestella), Uzbekistan (Nikiforovella, Rectifenestella), Russian Platform (Leptotrypa, Rectifenestella), Azerbaijan (Paranicklesopora), Ireland (Dyscritella), British Isles (Fistulipora, Rectifenestella), Eastern Transbaikalia (Rectifenestella, Dyscritella, Nikiforovella), Kurgan region (Nikiforovella, Rectifenestella, Leptotrypa), and Urals (Fistulipora) (nikiforova 1950; nekhoros-hev 1953, 1956; trizna 1958; lavrentJeva 1970, 1974; troizkaya 1975; bancroft 1988; yanG et al. 1988; bancroft & Wyse Jackson 1995; PoPeko 2000; ari-UnchimeG 2010; GorJUnova & lavrentJeva 2007).

6. Conclusions

The present paper provides the first detailed taxonomic description of Tournaisian bryozoans of Belgium. The studied fauna is represented by ten bryozoans, includ-ing five new species of the cosmopolitan genera Lep-totrypa, Dyscritella, Saffordotaxis, Spinofenestella and the genus Paranicklesopora with distribution in the Mississippian of Eurasia. In the Tournaisian close palaeobiogeographical connections can be traced be-tween Belgium, USA and some regions of Eurasia on genus level. The endemism of species is 90%.

Acknowledgements

zoya tolokonnikova thanks the Paleontological Society for financial support (PAlSIRP Sepkoski Grant 998X-14-60753-1). anDreJ ernst thanks the Deutsche Forschungsgemein-schaft (DFG) for financial support (project ER 278/6.1). Part of the work is performed according to the Russian Govern-ment Program of Competitive Growth of Kazan Federal Uni-versity. This study is a contribution to the IGCP 596 “Mid-Palaeozoic climate and biodiversity”. We are grateful to JUan lUis sUàrez anDrés, Santander, and Patrick Wyse Jackson, Dublin, for their useful comments.

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Manuscript received: May 4th, 2015.Revised version accepted by the Stuttgart editor: June 8th, 2015.

Addresses of the authors:

zoya tolokonnikova, Kuban State University, Kazan Federal University, Krasnodar, Russia. 353235 Aphipskij, Post box demand;e-mail: [email protected] ernst, Institut für Geologie, Universität Hamburg, Bundesstr. 55, 20146 Hamburg, Germany;e-mail: [email protected] Poty, Département de Géologie, Université de Liège, Batiment B18, Sart Tilman, 4000 Liège, Belgium;e-mail: [email protected]

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Appendix

Descriptive statistics. Abbreviations: N = number of measurements, X = mean, SD = sample standard deviation, CV = coef-ficient of variation, Min = minimum value, Max = maximum value.

Fistulipora sp. 1 N X SD CV MIN MAX

Aperture width, mm 20 0.24 0.037 15.35 0.18 0.32Aperture spacing, mm 10 0.39 0.057 14.62 0.32 0.48Vesicle diameter, mm 10 0.11 0.023 20.53 0.08 0.16Vesicles per aperture 4 8.5 0.577 6.79 8.0 9.0Vesicle spacing, mm 10 0.10 0.020 19.50 0.07 0.13

Fistulipora sp. 2N X SD CV MIN MAX

Aperture width, mm 13 0.22 0.019 8.97 0.19 0.25Aperture spacing, mm 13 0.49 0.052 10.66 0.42 0.60Vesicle diameter, mm 20 0.12 0.029 24.07 0.08 0.17Vesicles per aperture 6 8.2 0.753 9.22 7.0 9.0

Leptotrypa hexagona sp. nov.N X SD CV MIN MAX

Aperture width, mm 25 0.18 0.030 16.85 0.12 0.23Aperture spacing, mm 25 0.25 0.038 15.25 0.18 0.34Acanthostyle diameter, mm 25 0.05 0.009 18.73 0.03 0.06Acanthostyles per aperture 25 3.60 1.000 27.78 3.00 6.00Wall thickness in exozone, mm 8 0.07 0.007 9.75 0.06 0.08

Dyscritella ornata sp. nov.N X SD CV MIN MAX

Aperture width, mm 86 0.13 0.018 13.86 0.09 0.18Aperture spacing, mm 81 0.19 0.025 13.22 0.14 0.25Acanthostyle diameter, mm 81 0.039 0.012 30.85 0.015 0.060Exilazooecia width, mm 81 0.037 0.012 32.50 0.018 0.070Acanthostyles per aperture 45 4.4 1.401 32.16 2.0 8.0Exilazooecia per aperture 53 6.2 1.898 30.48 3.0 10.0

Trepostomata sp. indet.N X SD CV MIN MAX

Aperture width, mm 30 0.13 0.018 13.66 0.10 0.18Aperture spacing, mm 30 0.26 0.035 13.38 0.20 0.34Exilazooecia width, mm 12 0.047 0.020 42.12 0.025 0.08Acanthostyle diameter, mm 10 0.048 0.010 21.20 0.030 0.065Wall thickness in exozone, mm 10 0.12 0.010 8.41 0.11 0.14

Nikiforovella sp.N X SD CV MIN MAX

Aperture width, mm 11 0.14 0.009 6.39 0.12 0.15Metazooecia width, mm 10 0.05 0.013 27.26 0.03 0.07

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Saffordotaxis spinigerus sp. nov.N X SD CV MIN MAX

Branch width, mm 20 0.86 0.086 9.94 0.70 1.00Exozone width, mm 20 0.30 0.045 15.22 0.22 0.41Endozone width, mm 20 0.27 0.057 21.15 0.15 0.40Aperture width, mm 40 0.09 0.012 12.75 0.07 0.11Aperture spacing along branch, mm 40 0.51 0.048 9.50 0.40 0.60Aperture spacing diagonally, mm 40 0.29 0.033 11.32 0.23 0.36Aktinotostyle diameter, mm 40 0.05 0.009 18.05 0.04 0.07Autozooecial budding angle, mm 13 27.3 5.089 18.64 21.0 37.0

Paranicklesopora ornaisa sp. nov.N X SD CV MIN MAX

Branch width, mm 19 0.94 0.157 16.72 0.70 1.35Exozone width, mm 19 0.22 0.035 16.16 0.14 0.28Endozone width, mm 19 0.50 0.154 30.70 0.27 0.91Aperture width, mm 25 0.05 0.007 13.76 0.04 0.07Aperture spacing along branch, mm 25 0.34 0.036 10.64 0.30 0.40Aperture spacing diagonally, mm 25 0.22 0.025 11.45 0.17 0.26Acanthostyle diameter, mm 30 0.03 0.009 36.80 0.01 0.04

Spinofenestella nodosa sp. nov.N X SD CV MIN MAX

Branch width, mm 14 0.44 0.071 16.26 0.36 0.62Dissepiment width, mm 15 0.25 0.070 28.69 0.15 0.40Fenestrule width, mm 30 0.41 0.108 26.15 0.23 0.60Fenestrule length, mm 30 1.15 0.238 20.70 0.78 1.73Distance between branch centres, mm 30 0.75 0.135 18.03 0.50 1.00Distance between dissepiment centres, mm 30 1.49 0.262 17.57 1.00 2.00Aperture width, mm 30 0.12 0.015 13.18 0.09 0.15Aperture spacing along branch, mm 30 0.29 0.017 5.74 0.26 0.33Aperture spacing diagonally, mm 30 0.27 0.020 7.39 0.23 0.31Maximal chamber width, mm 30 0.16 0.012 7.69 0.14 0.18Apertures per fenestrule 10 5.5 1.080 19.64 4.0 7.0Keel node diameter, mm 10 0.09 0.012 13.36 0.08 0.11Keel node spacing, mm 7 0.61 0.043 7.13 0.55 0.68Node diameter, reverse side, mm 15 0.057 0.011 18.74 0.045 0.075

Rectifenestella rudis (Ulrich, 1890),N X SD CV MIN MAX

Branch width, mm 20 0.27 0.031 11.61 0.23 0.34Dissepiment width, mm 20 0.15 0.015 9.95 0.12 0.17Fenestrule width, mm 20 0.34 0.066 19.39 0.22 0.50Fenestrule length, mm 20 0.88 0.049 5.62 0.78 0.95Distance between branch centres, mm 20 0.59 0.048 8.18 0.50 0.70Distance between dissepiment centres, mm 20 1.04 0.060 5.81 0.94 1.15Aperture width, mm 20 0.09 0.009 10.44 0.08 0.11Aperture spacing along branch, mm 13 0.25 0.017 6.66 0.23 0.28Aperture spacing diagonally, mm 6 0.21 0.024 11.85 0.16 0.23Maximal chamber width, mm 20 0.12 0.010 8.24 0.10 0.14Apertures per fenestrule 9 4.2 0.441 10.44 4.0 5.0

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