Late Ordovician and Silurian lichid trilobites from northwestern Canada: Hemiarges, Borealarges , and Richterarges

Four new species of Borealarges, B. fritillus, B. patulus, B. renodis , and B. variabilis , and one new species of Richterarges, R. facetus , are described and one unnamed species, Borealarges sp., discussed. All are from the Wenlock strata of Avalanche Lake sections in the Mackenzie Mountains, Nort...

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Bibliographic Details
Published in:Journal of Paleontology
Main Authors: Campbell, Margaret J., Chatterton, Brian D. E.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2007
Subjects:
Paleontology
Arctic
Northwest Territories
Canada
Avalanche Lake
Mackenzie mountains
Online Access:http://dx.doi.org/10.1666/06-008.1
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000051842
Description
Summary:Four new species of Borealarges, B. fritillus, B. patulus, B. renodis , and B. variabilis , and one new species of Richterarges, R. facetus , are described and one unnamed species, Borealarges sp., discussed. All are from the Wenlock strata of Avalanche Lake sections in the Mackenzie Mountains, Northwest Territories. Borealarges tuckerae Adrain, 1994, the only species reported from both the Arctic and the Mackenzie Mountains, is discussed. Hemiarges avalanchensis n. sp., an Ashgill species from Avalanche Lake section AV 4B just below the Ordovician-Silurian boundary, is described. A phylogenetic analysis based on 14 species of Borealarges , three of Richterarges , and two of Hemiarges , demonstrates that the former two genera are three separate and distinct taxa. Borealarges , a genus that includes some species formerly assigned to Richterarges or Hemiarges , is monophyletic, contains a well-supported internal clade of species, and is not separated into senso stricto and senso lato groupings.

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