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Tenua
From Williams et al., 2017:
[Tenua, Davey, 1978, p.894.
Name illegitimate - senior homonym: Tenua Eisenack, 1958a.
Type species: Tenua rioultii, Sarjeant, 1968 (pl.1, fig.22; pl.2, fig.1)]
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Remarks:
Eisenack's type material of Cyclonephelium hystrix possesses the characteristics which typify the genus cyclonephelium - processes more or less restricted to a circumferential zone and an angular apical archeopyle- and it is therefore transferred to this genus. C. hystrix is characterized by numerous short, generally less than 10 µm, distally bifid processes and a rounded antapex. The above transference effectively removes the type species form Tenua Eisenack, 1958. However, Tenua was originally defined as having an overal covering of short processes, and has an obvious apical archeopyle. Hence the type species, T. hystrix, possessing bald areas, never precisely complied with the generic diagnosis. Since its erection, Tenua has been widely used and has come to be regarded as being characteristic of the later Jurassic and all the species subsequently erected have been of this age. Only the type species is of Cretaceaous age and this has fallen into disuse mainly because it does not comply with the generic diagnosis. It is hence here proposed to conserve the name Tenua, retaining Eisenack's original definition, and to erect T. rioulti Sarjeant as the new type species.
[Tenua, Davey, 1978, p.894.
Name illegitimate - senior homonym: Tenua Eisenack, 1958a.
Type species: Tenua rioultii, Sarjeant, 1968 (pl.1, fig.22; pl.2, fig.1)]
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Remarks:
Eisenack's type material of Cyclonephelium hystrix possesses the characteristics which typify the genus cyclonephelium - processes more or less restricted to a circumferential zone and an angular apical archeopyle- and it is therefore transferred to this genus. C. hystrix is characterized by numerous short, generally less than 10 µm, distally bifid processes and a rounded antapex. The above transference effectively removes the type species form Tenua Eisenack, 1958. However, Tenua was originally defined as having an overal covering of short processes, and has an obvious apical archeopyle. Hence the type species, T. hystrix, possessing bald areas, never precisely complied with the generic diagnosis. Since its erection, Tenua has been widely used and has come to be regarded as being characteristic of the later Jurassic and all the species subsequently erected have been of this age. Only the type species is of Cretaceaous age and this has fallen into disuse mainly because it does not comply with the generic diagnosis. It is hence here proposed to conserve the name Tenua, retaining Eisenack's original definition, and to erect T. rioulti Sarjeant as the new type species.