Morphologic variation of the Middle Devonian crinoid genus Haplocrinites from Poland

Abstract

A rich collection of well-preserved Middle Devonian crinoid thecae from Holy Cross Mountains (Świętomarz locality, Poland) is described. They are attributed to the widely distributed inadunate crinoid genus Haplocrinites. Using a traditional classification these thecae should be assigned to two species (H. aremoricensis and H. boitardi). However, a wide range of morphologic variation suggests that this assemblage represents morphological variants of a single species. This is supported by morphometric analyses which revealed that these thecae are not clustered into two morphologically distinct groups. These data show that the number of haplocrinitid species is likely overestimated. Traditional classifications based on the cup shape and ornamentation are no longer tenable, and require substantial revision. The diagnosis of H. boitardi is emended to encompass a broader range of morphologic variation. H. aremoricensis is a junior synonym of H. boitardi.