Ordovician microplankton (Baltisphaerids) from the Grötlingbo borehole no. 1 in Gotland, Sweden

The present study deals with a group of Ordovician phytoplankton with organic tests, baltisphaerids, derived from a continuous core drilled at Grötlingbo in Gotland. Fourty-three species belonging to genera Baltisphaeridium, Goniosphaeridium, Multiplicispbaeridium, Orthosphaeridium, and Peteinospbaeridium are described and biostratigraphically analyzed. Twenty-three new species are proposed, i. e.: Baltisphaeridium brevifilicum n. sp., Baltisphaeridium bulbosum n. sp., Baltisphaeridium constrictum n. sp., Baltisphaeridium echinatum n. sp., Baltisphaeridium filosum n. sp., Baltisphaeridium flagellicum n. sp., Baltisphaeridium granosum n. sp., Baltisphaeridium paucispinum n. sp., Baltisphaeridium psilatum n. sp., Baltisphaeridium ritvae n. sp., Baltisphaeridium triradiatum n. sp., Baltisphaeridium verrucatum n. sp., Goniosphaeridium conjunctum n. sp., Goniosphaeridium connectum n. sp., Multiplicisphaeridium continuatum n. sp., Orthosphaeridium trabeculatum n. sp., Peteinosphaeridium aequifurcatum n. sp., Peteinospbaeridium groetlingboensis n. sp., Peteinospbaeridium heteromorphicum n. sp., Peteinospbaeridium majorfurcatum n. sp., Peteinosphaeridium majorvesiculum n. sp., Peteinospbaeridium nanofurcatum n. sp., and Peteinospbaeridium velatum n. sp. Two genera, Goniosphaeridium and Orthosphaeridium, are emended.