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Nexosispinum sp.
Nexosispinum sp.
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Genus: Nexosispinum Davey, 1979
tax. jr. synonym of Kiokansium Stover and Evitt, 1978, according to Stover and Williams, 1987. Prössl, 1990, retained Nexosispinum as a separate genus.
Type species: Nexosispinum hesperum Davey, 1979
Original description: Davey, 1979, p. 558
The cysts are spherical to subspherical and bear numerous, relatively short, solid processes which are apparently randomly arranged; they are of constant size upon an individual specimen. The processes are either simple or they anastomose with one or more neighboring processes, sometimes forming an irregular network of linkages. Distally the processes are accuminate [sic], capitate or briefly bifurcate. The archeopyle is precingular, formed by the loss of two plates (type 2P).
Affinities:
Stover and Williams, 1987, p. 163: Both Nexosispinum and Kiokansium Stover and Evitt 1978 emended Duxbury 1983 have solid, nontabular processes with acuminate to slightly branched tips and type 2P archeopyles. However, in Nexosispinum some processes anastomose, generally proximally or medially, in an uncomplicated manner with one or two adjacent processes, and the cyst body is subspherical. Kiokansium lacks the proximal-medial connecbons between processes and has an ellipsoidal body. However, we regard the morphologic differences to be of specific rather than generic taxonomic value. Accordingly, we consider Nexosispinum to be a junior synonym of Kiokansium.
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Genus: Nexosispinum Davey, 1979
tax. jr. synonym of Kiokansium Stover and Evitt, 1978, according to Stover and Williams, 1987. Prössl, 1990, retained Nexosispinum as a separate genus.
Type species: Nexosispinum hesperum Davey, 1979
Original description: Davey, 1979, p. 558
The cysts are spherical to subspherical and bear numerous, relatively short, solid processes which are apparently randomly arranged; they are of constant size upon an individual specimen. The processes are either simple or they anastomose with one or more neighboring processes, sometimes forming an irregular network of linkages. Distally the processes are accuminate [sic], capitate or briefly bifurcate. The archeopyle is precingular, formed by the loss of two plates (type 2P).
Affinities:
Stover and Williams, 1987, p. 163: Both Nexosispinum and Kiokansium Stover and Evitt 1978 emended Duxbury 1983 have solid, nontabular processes with acuminate to slightly branched tips and type 2P archeopyles. However, in Nexosispinum some processes anastomose, generally proximally or medially, in an uncomplicated manner with one or two adjacent processes, and the cyst body is subspherical. Kiokansium lacks the proximal-medial connecbons between processes and has an ellipsoidal body. However, we regard the morphologic differences to be of specific rather than generic taxonomic value. Accordingly, we consider Nexosispinum to be a junior synonym of Kiokansium.