DEAN, C.D., SUTTON, M.D., SIVETER, D.J., SIVETER, D.J. 2015. A novel respiratory architecture in the Silurian mollusc Acaenoplax. Palaeontology, 58, 5, 839-847. DOI: 10.1111/pala.12181
Christopher D. Dean, Mark D. Sutton, Derek J. Siveter, and David J. Siveter- Christopher D. Dean - Imperial College London Department of Earth Sciences and Engineering London UK (Email: christopher.dean09@imperial.ac.uk)
- Mark D. Sutton - Imperial College London Department of Earth Sciences and Engineering London UK (Email: m.sutton@imperial.ac.uk)
- Derek J. Siveter - University Museum of Natural History Earth Collections Oxford UK (Email: derek.siveter@oum.ox.ac.uk; dereks@earth.ox.ac.uk)
- Derek J. Siveter - University of Oxford Department of Earth Sciences Oxford UK
- David J. Siveter - University of Leicester Department of Geology Leicester UK (Email: djs@le.ac.uk)
- Issue published online: 28 August 2015
- Article first published online: 01 January 1970
- Manuscript Accepted: 29 May 2015
- Manuscript Received: 19 January 2015
Extant aplacophorans, a group of shell‐less vermiform molluscs, respire through appendages within or projecting from a posterior cavity. Respiratory structures differ between the subclasses Caudofoveata (ctenidia within the cavity) and Solenogastres (folds of the mantle itself). Acaenoplax hayae, a Silurian vermiform mollusc from the Herefordshire Lagerstätte, England, exhibits characteristics of both these groups. While recent work places it within the crown group Aplacophora, near the caudofoveates, initial observations suggested that its respiratory structures were closer to those of the solenogastres. Here, we present new reconstructions of the posterior of Acaenoplax prepared with the aim of resolving features obscured when prior studies were undertaken. These reconstructions detail a novel posterior architecture, not closely comparable to that of either extant aplacophoran group, in which respiratory projections arise from a membrane that partly encloses a central posterior cavity. The posterior membrane is flanked by small spherical projections; both membrane and spherical projections are apparently unique within the Aplacophora. The existence of this previously undocumented respiratory system underlines the diversity of the aplacophoran clade during the Palaeozoic.
Data for this study are available in the Dryad Digital Repository http://dx.doi.org/10.5061/dryad.s7193 Wiley Online Library