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Ernst et al.—New caledonian Triassic bryozoan


Table 1. Descriptive statistics of Metastenodiscus zealandicus (Schäfer and Grant-Mackie, 1994)


Paramter


Aperture width, mm Aperture spacing, mm


N X SD CV MIN MAX 50 0.26 0.028 11.01 0.22 0.35


Aperture width in maculae, mm 20 0.34 0.045 12.95 0.28 0.44 Acanthostyle diameter, mm Acanthostyles per aperture


50 0.33 0.043 12.89 0.28 0.49 50 0.07 0.019 27.14 0.03 0.12


Macroacanthostyle diameter, mm 50 0.16 0.034 21.45 0.11 0.25 Heterozooecia diameter, mm


Autozooecial diaphragm spacing, mm 30 0.20 0.087 44.12 0.10 0.43 Exozonal wall thickness, mm


40 5.6 1.659 29.50 2.0 11.0 40 0.095 0.029 31.05 0.045 0.180 20 0.041 0.018 44.22 0.01 0.07


CV = coefficient of variation; MAX = maximal value; MIN = minimal value; N = number of measurements; SD = sample standard deviation; X = mean.


diaphragms usually abundant, straight or slightly curved distally. Acanthostyles moderate to large, varying in size throughout the colony, possessing narrow cores of hyaline material and wide laminated sheaths, originating in exozone, two to seven surrounding each autozooecial aperture. Heterozooecia representing narrow tubes abundant, locally containing thin diaphragms, originating at the base of exozone, 3–10 surrounding each autozooecial aperture. Autozooecial walls thin, displaying granular microstructure, 0.010–0.015mm thick in endozone; merged, showing distinct convex lamination without visible zooecial boundaries, moderately to strongly thickened, non-beaded, 0.03–0.10mm thick in exozone.


Material.—Warepan of Ile Ducos: NC/f533 (AU7188-(1-2)). Warepan of Ile Page: NC/f336 (AU7786). Otapirian of Ile Hugon : NC/f7 (AU7149d, e); Warepan of Ile Hugon NC/f89 (AU7141(1, 6, 9, a, f)).


Occurrence.—New Zealand; upper Carnian to lower Norian, Oretian. New Caledonia, Ile Ducos, Ile Page; Upper Triassic, Norian, Warepan. New Caledonia, Ile Hugon; Upper Triassic, Norian, Warepan. New Caledonia, Ile Hugon, Hill 121; Upper Triassic, Rhaetian, Otapirian.


Remarks.—The present material is similar to Dyscritellopsis isoseptatus Schäfer and Grant-Mackie, 1994 from the upper Carnian to lower Norian of New Zealand. The New Zealand material has fewer heterozooecia. Dyscritellopsis isoseptatus differs from D. montelloensis Schäfer, Cuffey and Young, 2003 from the Lower Triassic of Nevada, USA in its branched and encrusting instead of massive colony form and in having larger autozooecial apertures (average autozooecial aperture width 0.26mm vs. 0.15mm in Dyscritellopsis montelloensis).


Genus Arcticopora Fritz, 1961


Type species.—Arcticopora christiei Fritz, 1961. Lower Triassic (upper Dienerian – lower Smithian); Ellesmere Island, Canada.


Diagnosis.—Cylindrical, branching and encrusting colonies. Significant distinction between endozone and exozone. Endozone thin-walled, autozooecia polygonal in transverse section; budding pattern of autozooecia acyclical in zooecial corners (interzooecial). Autozooecia long in endozone, almost parallel to zoarial growth direction, rapidly bending outward


739


in endozone, meeting colony surface at 90° angles. Basal diaphragms locally present, more common in transition between endozone and exozones. Autozooecial apertures irregularly rounded to oval in shallowest tangential section, indented by acanthostyles, more angular in slightly deeper tangential sec- tion, arranged randomly on colony surface. Basal diaphragms common in exozones. Zooecial walls moderately thickened in exozone, non-beaded. Distinctly convex lamellar wall micro- structure, zooecial boundaries amalgamated. Heterozooecia abundant, originating in the inner exozone, basal diaphragms present or absent. Distinct difference in diameter between autozooecia and smaller heterozooecia. Acanthostyles common but irregularly scattered, moderately thick, of one size, origi- nating in endozone or exozone.


Occurrence.—Lower-Upper Triassic; Canada, Europe, Japan, Siberia, Caucasus, New Zealand, New Caledonia.


Remarks.—Arcticopora Fritz, 1961 differs from Pseudobatos- tomella Morozova, 1961 in possessing a less regular budding pattern of autozooecial apertures and more abundant diaphragms. Furthermore, Arcticopora develops colonies of branched and encrusting sheets, whereas Pseudobatostomella is known only as a branching form. Arcticopora differs from Dyscritella Girty, 1911 in the presence of diaphragms and less by the lack of diaphragms in the latter genus. Additionally, Dyscritella possesses exilazooecia, heteromorphs without diaphragms, whereas heterozooecia in Arcticopora have variable numbers of diaphragms.


Arcticopora lobatula (Schäfer and Grant-Mackie, 1994) Figures 9.6–9.7, 10.1–10.6; Table 3


1994 Pseudobatostomella lobatula Schäfer and Grant-Mackie, p. 19, figs. 18-21


Holotype.—BZ159. BZ160. Institute of Geological and Nuclear Sciences Limited (GNS Science), Lower Hutt, New Zealand.


Description.—Branched colonies, branch diameter 1.7–4.2mm. Endozone 0.9–1.4mm wide, exozone 0.4–1.6mm wide. Secondary overgrowths uncommon. Autozooecia long in endozone, having polygonal shape in transverse section, bend- ing at angles of 30°–51° in exozone and intersecting colony surface at angles of 83°–88°. Autozooecial apertures oval to subpolygonal and strongly petaloid due to indenting acantho- styles. Autozooecial diaphragms rare or absent in the endozone, rare to abundant in the exozone, thin and planar. Autozooecial walls thin, displaying granular microstructure, 0.01- to 0.02-mm thick in endozone; merged, showing distinct convex lamination without visible zooecial boundaries, moderately to strongly thickened, non-beaded, 0.05- to 0.16-mm thick in exozone. Acanthostyles moderate to large, possessing narrow cores of hyaline material and wide laminated sheaths, originating in exozone, four to ten surrounding each autozooecial aperture. Heterozooecia representing narrow tubes rare, small, rarely containing thin diaphragms, originating at the base of exozone. Maculae indistinct consisting of slightly larger autozooecia and


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