Jardamarekia, Frýda, Jiří, Blodgett, Robert B., Lenz, Alfred C. & Frýdová, Barbora, 2011

Frýda, Jiří, Blodgett, Robert B., Lenz, Alfred C. & Frýdová, Barbora, 2011, Jardamarekia enigma, a new Early Devonian tryblidioidean from Royal Creek area (Yukon Territory, Canada), and paleobiogeography of the Early Devonian of northwestern Canada, Zootaxa 2905, pp. 57-62 : 59-60

Jardamarekia gen. nov.

Type species: Jardamarekia enigma sp. nov. from middle Early Devonian (Pragian) age strata of the Road River Formation in the Royal Creek area, Yukon Territory, Canada (64.8° N, 135.2° W).

Diagnosis. Medium-sized limpet shell (maximal shell diameter about 26 mm) with rounded apertural outline; apex overhanging, apex position at half of shell height; maximum shell height about half of shell length; shell slightly wider than high; shell ornamentation consists of strong collabral and slightly adapically curved ribs; height of ribs about double that of their width; space between ribs ornamented by radial threads, intersecting with collabral ribs to form distinct, regular, reticular pattern.

Differences. Jardamarekia gen. nov. resembles Ladamarekia from the Early Devonian Pragian strata of the Prague Basin in its shell ornamentation, but is easily distinguished by the shape and size of its shell. The type and only known species of Ladamarekia, L. miranda has a much higher shell than J. enigma ( Fig. 2 ). Also the expansion rate of the shell in the former species is much slower than in J. enigma . The shells of the latter species are about four times larger than those of L. miranda . The new genus also resembles the type and only known species of genus Pilinopsis , P. eminens ( Perner, 1903) . Because only a single shell of the latter species is known (see Horný 1962: p. 10), knowledge of its shell features is limited. Jardamarekia differs from Pilinopsis in having a higher shell (because of faster expansion rate of its shell), protruding shell apex, much thicker shell and a very distinct shell ornament (compare figures 6–8, pl. III, in Horný 1962 with Fig. 2 ).

Etymology. Jardamarekia (femininum), in honor of Jaroslav Marek, Czech paleontologist and teacher at Charles University (Prague).

Figures

FIGURE 2. Jardamarekia enigma sp. nov. from middle Early Devonian (Pragian) age strata of the Road River Formation in the Royal Creek area, Yukon Territory, Canada. The species is from interval 142.0 – 150.0 m of section 1 (Fig. 1 A). Holotype GSC 134793: A – C, F, H – N, shell length 18 mm, width 14 mm, height 10 mm; figure width of shell details: H— 11 mm, I— 10 mm, J— 8 mm, K— 3,5 mm, L— 10 mm, M, N— 3 mm. Paratype: GSC 134794: D – E, G, shell length 26 mm, width 21 mm, height 11 mm.