Jardamarekia enigma, a new Early Devonian tryblidioidean from Royal Creek area (Yukon Territory, Canada), and paleobiogeography of the Early Devonian of northwestern Canada Author Frýda, Jiří Author Blodgett, Robert B. Author Lenz, Alfred C. Author Frýdová, Barbora text Zootaxa 2011 2905 57 62 journal article 46759 10.5281/zenodo.206868 e62210f9-f1bd-4dde-8f76-7c88fc32f004 1175-5326 206868 Jardamarekia enigma sp. nov. Fig. 2 A–N Holotype . GSC 134793 ( Fig. 2 A–C, F, H–N). Paratype . GSC 134794 ( Fig. 2 D–E, G). Type locality. Middle Early Devonian (Pragian) age strata of the Road River Formation in the Royal Creek area, Yukon Territory, Canada . It comes from interval 142.0–150.0 m ( 466–492 feet ) of section 1 ( Fig. 1 ), which belongs to the fauna of Pragian age with the brachiopod Davidsoniatrypa johnsoni Lenz, 1968 ( Lenz 1977b ). Etymology. enigma —from Latin aenigma (something inexplicable). Diagnosis. Because of monotypic genus, see that of genus. Description. Two well-preserved, silicified, almost complete shells. Shells medium-sized, spoon shaped with distinctly protruding apex; maximum length about 27 mm . Shell as high as wide, twice as long. Aperture elliptical, apertural margin in one plane. Protruding shell apex in middle of shell height, distinctly overhanging anterior margin of aperture ( Fig. 2 C–E). Outer shell surface ornamented by strong concentric lamellae, comarginal with aperture. Lamellae crossed by radial threads. Comarginal lamellae, radial threads regularly spaced, forming distinct reticular shell ornamentation at their intersections ( Fig. 2 A–C, J, K). Distance between lamellae about twice distance between radial threads. Because of more rapid shell growth in dorsal part of shell, distance between comarginal lamellae in dorsal region higher than in anterior region below shell apex. Lamellae adapically bent, height equals to their distance of separation. Width of each lamella about half of its height ( Fig. 2 M–N). Shell apex blunt, cap-shaped without traces of spiral coiling ( Fig. 2 C, H–I). Shell thickness about equal to width of comarginal lamellae ( Fig. 2 N).