NEW GENERA OF PALEOZOIC POLYPLACOPHORA (MOLLUSCA)

Abstract

The opportunity to study some of de Koninck's (1883) type specimens from the Institut Royal de sciences Naturelle de Belgique (RMNS), specimens from the British Museum of Natural History (BMNH), and from the Museum of Comparative Zoology, Harvard University (MCZ) has provided insight into the taxonomic relationships of some polyplacophoran taxa. It is evident that errors have occurred in relating various specimens to taxa which differ significantly. Two examples of this related to a Devonian species in Germany and a Permian species in the United States National Museum of Natural History (USNM) are clarified and illustrated. ### Class Polyplacophorade Blainville, 1816 Order Paleoloricata Bergenhayn, 1955 Suborder Chelodina Bergenhayn, 1943 Family Helminthochitonidae Van Belle, 1975 Genus Diadelochiton new genus Chiton corrugatus Sandberger and Sandberger, 1853–1855, p. 238, pl. 26, fig. 22, 22b, 22c, (not figs. 22a, d). #### Type species Diadelochiton recavus new species, monotypy. #### Diagnosis Intermediate plates strongly arched; anterior margin with deep jugal sinus; anterior two-thirds of jugal area depressed, bordered by sharp emarginations. #### Etymology Greek, diadelos, distinguishable plus chiton, tunic. #### Occurrence Devonian (Givetian) Stringocephalenkalk at Villmar and (Frasnian) reef complex at Winterberg, Germany. #### Discussion Sandberger and Sandberger (1853–1855, p. 238, pl. 16, fig. 22, 22a–d) described and illustrated Chiton corrugatus from the Stringocephalenkalk at Villmar, Germany. Previously, G. Sandberger (1842, p. 387, 399) had listed C. subgranosus (nomen nudum) which name he changed to C. corrugatus for unknown reasons. Dall (1882, p. 281) selected figure 22a of the Sandbergers for the type specimen of a new genus Probolaeum , type species C. corrugatus . The specimens illustrated in figure 22, 22c, and probably 22b by the Sandbergers are significantly different …