Revision of the suborder Synziphosurina (Chelicerata, Merostomata) : with remarks on merostome phylogeny. American Museum novitates ; no. 2543

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New York, N.Y. : American Museum of Natural History
"A new genus and species of the merostome suborder Synziphosurina is described from the Lower Devonian of Bolivia. This new taxon has made possible a reinterpretaion of other poorly understood genera commonly allocated to the Synziphosurina. Weinbergina Richter and Richter, Bunodes Eichwald, Bunaia Clarke, and Pseudoniscus Niezkowski are re-examined in detail, based mainly on a study of the original material, as well as on collections of topotypical specimens of Bunodes lunula Eichwald and Pseudoniscus aculeatus Niezkowski. Shorter discussions are presented for Neolimulus Woodward and Limuloides Salter in Woodward. Weinbergina and the new Bolivian genus are monotypic. Each is known from only three specimens, and both occur in Lower Devonian marine rocks. Bunodes as presently understood is also monotypic: B. lunula from the Upper Silurian of Oesel; some British Silurian species described as Limuloides are probably referable to Bunodes. The three described species of Pseudoniscus (P. aculeatus Niezkowski from Oesel; P. roosevelti Clarke, and P. clarkei Ruedemann from New York State), all Upper Silurian in age, are difficult to differentiate, and only the genus is rediagnosed. In addition, two specimens of Pseudoniscus are now known from the Silurian of Great Britain. Neolimulus, based on a single specimen from the Upper Silurian of England, is poorly known and apparently closely related to Pseudoniscus. Bunaia is based on four specimens (from the Upper Silurian of New York) and may be a junior synonym of Pseudoniscus. The suborder Synziphosurina is rediagnosed and contains but four valid genera: Weinbergina, Bunodes, Limuloides, and the new Bolivian taxon. The families Weinberginidae (Weinbergina and the Bolivian genus) and Bunodidae (Bunodes and Limuloides) are recognized. The suborder Limulina is the sister group of the Synziphosurina, and in turn is comprised of the infraorders Pseudoniscina (diagnosed herein) and Limulicina. Pseudoniscus, Bunaia, and Neolimulus are referred to the Pseudoniscina, as is an unnamed family of primitive belinurid limulines in which the axis of the opisthosoma is broader than the prosomal cardiac lobe at the juncture of these two tagmata. A classification of the class Merostomata is presented: the Aglaspida comprise the sister group of the Xiphosurida (i.e., Synziphosurina and Limulina) and the Eurypteridida and Chasmataspida are probably sister taxa. Two merostome subclasses, the Eurypterida and Xiphosura, are recognized. Finally, there is a brief discussion of evolutionary patterns within the Merostomata, with emphasis on the Xiphosurida"--P. 3.
41 p. : ill. ; 26 cm.
Includes bibliographical references (p. 39-41).