NEOTYPE AND REDESCRIPTION OF THE UPPER CAMBRIAN ANTHASPIDELLID SPONGE, WILBERNICYATHUS DONEGANI WILSON, 1950

摘要

The Upper Cambrian sponge Wilbernicyathus donegani Wilson, 1950 was originally described as an archaeocyath. The original specimens were lost. Later, based on the original description and figures, this species was interpreted as an orchocladine lithistid, but family-level taxonomy has not been clear. A neotype is designated to help stabilize the taxonomy of this species. A redescription based on the neotype and other new material from the area of the type locality and elsewhere demonstrates that this species is an orchocladine lithistid sponge belonging to the family Anthaspidellidae. It has a regular skeleton consisting of dendroclones and trabs arranged in a ladderlike net, and radial canals are well organized. The species occurs within sponge-microbial and stromatolitic reefs in the Wilberns Formation of central Texas and possibly the Clinetop Bed of the Dotsero Formation of Colorado. Stratigraphically, it ranges from the Idahoia to the Saukia trilobite zones of the Upper Cambrian Ptychaspid Biomere. Ecologically, Wilbernicyathus Wilson, 1950 occupies a reefal niche and constitutes up to 30% of the reef volume. These Late Cambrian bioherms represent the initial Laurentian expansion in the sponge-microbial buildups that dominated reef environments worldwide during the Early Ordovician.