A revision of the rare genus Cyclolampas (Echinoidea) using morphometrics with description of a new species from the upper Callovian of Burgundy (France).

18 pagesInternational audienceThe discovery of a new species, Cyclolampas altus new species in the upper Callovian of Burgundy (France) leads to the systematic revision of the rare echinoid genus Cyclolampas Pomel, 1883. Two morphometric approaches are used jointly to describe and quantify variations in test shape: the analysis of linear measurements and the Elliptic Fourier shape analysis. Both analyses yield congruent results that highlight the amplitude of within-species variations and quantify the part due to allometry. Along with the description of C. altus, the systematic position of species formerly assigned to the genera Pygorhytis Pomel, 1883 and Cyclolampas is amended. Previously attributed to the genus Pygorhytis, Cyclolampas castanea (Desor, 1858) is reassigned to the genus Cyclolampas on the base of new observations. Conversely, the examination of the Bajocian species Pygorhytis kiliani (Lambert, 1909) and Pygorhytis gillieroni Desor in Desor and de Loriol, 1872, which were previously assigned to Cyclolampas now supports their taxonomic reassignment to the genus Pygorhytis. Finally, the two species Cyclolampas verneuili (Cotteau, 1870) and Cyclolampas cotteaui Mintz, 1966 (nomen nudum) are considered junior synonyms of the genus type species Cyclolampas voltzii (Agassiz, 1839). The questioned origin date of the genus, estimated either to the Bajocian or to the Oxfordian, is now clearly established to be upper Callovian. These new results fit well with the overall scheme of atelostomate echinoid evolution and migration to deep-sea environments during the Middle and Upper Jurassic