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Alpeis tolenensis
Taxonomy
Mimella tolenensis was named by Borissiak (1972) [= 1955 Doleroides sp.; Borissiak: 32, pl. 1, figs 5–10.]. Its type specimen is CNIGR 1/9555, a shell (partly exfoliated conjoined valves), and it is a 3D body fossil. It is the type species of Alpeis.
It was recombined as Hirnantia tolenensis by Klenina (1984); it was recombined as Alpeis tolenensis by Popov and Cocks (2014).
It was recombined as Hirnantia tolenensis by Klenina (1984); it was recombined as Alpeis tolenensis by Popov and Cocks (2014).
Synonymy list
Year | Name and author |
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1972 | Mimella tolenensis Borissiak p. 174 figs. pl. 47, figs 1–3 |
1984 | Hirnantia tolenensis Klenina p. 50 figs. pl. 3, fig. 2, pl. 6, figs 11, 15, 17 |
2014 | Alpeis tolenensis Popov and Cocks pp. 740 - 741 figs. 21V–Y, 22I–R, T) |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Alpeis tolenensis Borissiak 1972
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Diagnosis
Reference | Diagnosis | |
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L. E. Popov and L. R. M. Cocks 2014 | Shell strongly dorsibiconvex, slightly transverse, suboval to almost circular in outline, about 70% as long as wide. Hinge line significantly shorter than maximum width at mid-length (80%); cardinal extremities broadly rounded. Anterior commissure slightly unipicate. Ventral valve profile moderately convex, with maximum height at one-third to one-quarter valve length. Ventral interarea moderately high, triangular, almost planar, strongly apsacline to almost catacline, with narrow triangular delthyrium with incipient deltidial plates on the margins. Weakly defined ventral sulcus developed anteriorly to mid-length. Dorsal valve lateral profile strongly convex, more strongly curved in the posterior half, with maximum height slightly posterior to the mid-length. Umbonal region strongly swollen, hanging slightly over the hinge line. Dorsal interarea curved, almost orthocline. Radial ornament finely multicostellate, with 6 to 8 ribs per 3 mm along the anterior margin of mature specimens. Ventral interior with strong teeth supported by long, divergent dental plates. Ventral muscle field small, subtriangular, strongly impressed, with anterior border between a quarter and one-third valve length mainly within the floor of the delthyrial cavity. Adductor scar subtriangular, raised anteriorly, slightly longer and wider than gently impressed diductor scars. Mantle canal system strongly impressed, saccate, with vascula arcuata branching from widely spaced vascula media at a short distance from the outer boundary of diductor scars. Dorsal interior with a narrow and deep notothyrial cavity occupied almost completely by a posteriorly bilobed cardinal process supported by a low, narrow shaft not differentiated from a faint median ridge bisecting weakly impressed adductor muscle field. Brachiophores triangular, blade-like, with widely divergent bases almost parallel to the hinge line. Sockets deep, transverse, subtriangular, with well-developed fulcral plates. |