New, distinctive, well preserved and previously undescribed constituents of a Middle Ordovician (middle Darriwilian, Dw2) radiolarian assemblage from the Table Cove Formation in Newfoundland are described. Three-dimensional X-ray micro-computed tomography (μ-CT) facilitates detailed examination of key specimens revealing hitherto unknown details of the internal morphologies of key lower Paleozoic taxonomic groups amongst which a lack of knowledge has previously impeded resolution of higher taxonomic rankings. 

Twenty-seven archaeospiculid and entactinarian taxa are described and illustrated including six new species: Westernbrookia polygonata n. sp., Neopalaeospiculum piccadilliensis n. sp., Ramuspiculum laxum n. sp. Spongentactinianazarovi n. sp., Aspiculum irregulare n. sp., Nyfrieslandia ramosissima n. sp., 

The investigation extends the known  ranges of the species: Pararcheoentactinia reedae Won and Iams 2002, Sphaeroentactinia robusta Won, 2015, Varispiculum ectospiculatum Won 2015, and Svalbardospiculum multifurcatum (Won, Iams and Reed) 2005, together with the genus Echidnina to the mid-Darriwilian.

SEM imagery acquired with a Hitachi TM3030 desktop SEM

μ-CT imaging acquired with a Xradia Versa 500 scanner

imagery processed using Avizo® 9.4 software for 3D visualization and data analysis.