Articulated endoskeletons of the Devonian disparid Storthingocrinus: implications for the revision of a misunderstood crinoid genus

The discovery of new specimens and restudy of known collections result in revision of the disparid crinoid genus Storthingocrinus, known from the Middle Devonian of Europe and Asia. High ecophenotypic plasticity of the common S. fritillus negates the validity of several former subspecies and demonstrates the general morphologic variability of the cup proportions. This requires the definition of interspecific distinguishing features based on the description of articulated crowns. Three new species are described (Storthingocrinus coronatus n. sp., S. ebbighauseni n. sp., and S. lobatus n. sp.). A neotype is proposed for the lost original of S. fritillus. The proposed interpretation of Storthingocrinus trifidus as a stemless and pelagic crinoid is rejected, and its subgeneric status is dissolved based on the first recovery of articulated crowns with attached stems. Because “Storthingocrinus sphaericus” from the Upper Devonian of Germany is excluded from Storthingocrinus, and “Storthingocrinus haugi” as well as “Storthingocrinus labiatus” from the Lower Devonian of Spain were listed in the Official Index of Rejected and Invalid Specific Names in Zoology by the International Commission on Zoological Nomenclature (ICZN), the stratigraphic range of the genus is restricted to the Middle Devonian. The genus populated the southeastern shelf realm of Laurussia within the Rheic Ocean about 31°S latitude (Germany, Czech Republic; Europe), and the Prototethys/Paleotethys Ocean about 27°S latitude (Burma; Asia). A monobathrid camerate species from the Middle Devonian of the Eifel Synclines, which was incorrectly assigned to Storthingocrinus decagonus, is redescribed as Bohnerticrinus nilsjungi n. gen. n. sp.