Silurian Archaeoscyphia from the Canadian Arctic: a case for simplified generic taxonomy in the anthaspidellid lithistids (Porifera)

• Published in: Canadian Journal of Earth Sciences
• Main Author: Freitas, Tim A. de
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1989
• Subjects: Arctic; Rigby
• Online Access: http://dx.doi.org/10.1139/e89-159; http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-159

Abundant anthaspidellid orchoclad lithistids occur in thin biostromes of Wenlockian age of the Canadian Arctic. The sponges are well preserved, and many have similar internal architecture. Synonymization of Calycocoelia Bassler, 1927, Rhopalocoelia Raymond and Okulitch, 1940, Somersetella Rigby and Dixon, 1979, and Steliella Hinde, 1889 under the genus Archaeoscyphia Hinde, 1889 is necessary in light of continuous morphological variation of the more than 100 specimens in the study collection. Synonymization takes into consideration various features formerly used to define the five taxa, including parietal width, canal diameter, annulation, presence of monaxons in trabs, dermalia, position of the trab-pinnation surface, spicule dimension, and canal disposition. Several features previously thought to be distinctive generically are shown to be species significant or to be a result of variation within a single species or specimen.