Resolution of taxonomic ambiguities among siliceous Cambrian microfossils: poriferan affinity of Blastulospongia and phylogeny of archaeospicularians (Radiolaria)

A new species of Blastulospongia Pickett and Jell, 1983 from the middle Cambrian Devoncourt Limestone, Georgina Basin, Australia exhibits distinct perforation patterns characteristic of sphinctozoans. Recognition as a sphinctozoan-grade sponge confirms the poriferan affinity of this enigmatic genus, which appeared prior to the development of other hypercalcified sponge forms of chaetetids and stromatoporoids. Blastulospongia bouliaensis new species occurs together with four species of primitive spicular radiolarians: Echidnina irregularis Won in Won and Iams, 2002, Parechidnina aspinosa Won in Won and Below, 1999, Palaeospiculum reedae Won in Won and Below, 1999, and Palaeospiculum devoncourtensis Won in Won and Below, 1999. Micro-computed tomographic (MCT) analysis of Parechidnina aspinosa reveals its skeletal construction through the fusion of unirayed spicules, indicating a close phylogenetic link with archeoentactinids. Blastulospongia bouliaensis n. sp. and Palaeospiculum devoncourtensis represent promising Miaolingian accessory species for biostratigraphy during the Drumian-Guzhangian interval. UUID: http://zoobank.org/a74cdd4d-6bc3-427b-bf4c-d4f0b79a5c91