Discometra Gislèn, 1924

Eléaume, Marc, Roux, Michel & Philippe, Michel, 2020, Discometra luberonensis sp. nov. (Crinoidea, Himerometridae), a new feather star from the Late Burdigalian, European Journal of Taxonomy 729, pp. 121-137 : 126-127

Genus Discometra Gislèn, 1924

Type species

Eugeniacrinus ? rhodanicus Fontannes, 1877 .

Emended diagnosis

Centrodorsal hemispherical to low hemispherical or discoidal; cirrus-free aboral apex concave or flattened; adoral side with inter-radial ridges; cirrus sockets with or without low transverse rectangular ridge and closely placed, often in 3 (rarely 5) irregular rows. Cirrals without aboral spines. Radials with internal, Y-shaped coelomic canals just beneath proximal surface; radial circlet nearly equal to or lower and narrower than centrodorsal; interarticular ligament fossae large, separated by wide midradial area. Rod-shaped basals absent. Numerous arms, up to about 60; brachitaxes with 2 or 4 ossicles (2 frequent beyond tertibrachitaxis); ligamentary synarthry at br1-2; syzygy with radiating crenularium at br3+4; ligamentary articulations irregularly placed beyond br5.

Remarks

Gislén (1924) designated D. rhodanica as the type species of the genus, so it is important to clarify and complete the description with the new data provided here. Discometra is mainly distinguished from all other genera of Himerometridae by its internal coelomic canals located near the aboral surface of the radials.

Geographical distribution

From southeastern France (this study) to northern and central Italy ( Noelli 1900; Airaghi 1904; Albus 1930), central Europe and Poland (Sieverts-Doreck 1961; Radwańska 1987) as well as Algeria ( Pomel 1885 –1887) and possibly Egypt (cited by Fourtau 1920 but without illustration), in the Early and Middle Miocene.

Included species

Discometra eggenburgensis (Schaffer, 1912) , D. luberonensis sp. nov., D. michelottii ( Noelli, 1900) , D. rhodanica ( Fontannes, 1877) and D. speciosa ( Pomel, 1885) .