Redescription of Schizobrissus mauritanicus Pomel, 1885, on the basis of new topotypic material from the Lower Miocene of the Oran region (northwestern Algeria)

Mohamed Belkercha ¹, Fadila Yacef ¹, Bruno Ferré ², Mohamed Bendella ³, Mustapha Bensalah ⁴, Loïc Villier ⁵ & Mansour Zaagane ^6
1Département des Sciences de la Terre et de l’Univers, Université Hassiba Benbouali de Chlef. Faculté de Génie civil et d’Architecture, Pôle Universitaire Ouled Fares, DZ-2010 Chlef, Algeria, ²2 rue Guy de Maupassant, F-76800 Saint Étienne du Rouvray, France, ³Mohamed Ben Ahmed Oran 2 University, Laboratory of Basin Geodynamics and Sedimentary Balance, P.O. Box 1524, El M’Naouer, DZ-31000 Oran, Algeria, ⁴Laboratoire de Recherche n° 25, Université Abou-Bekr Belkaid, DZ-13000 Tlemcen, Algeria, ⁵Université Pierre & Marie Curie Paris VI, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P), F-75252 Paris CEDEX 05, France, ⁶University of Mascara, Mustapha Stambouli, Mascara, DZ-29000, Algeria

Schizobrissus mauritanicus Pomel, 1885, is an extinct species of echinoid from the Lower Miocene of Algeria, indicated by Pomel (1885) as the type species of the genus Schizobrissus Pomel, 1869, but subsequent authors established Brissus cruciatus (Agassiz in Agassiz & Desor, 1847a) as type species. New collections within the type locality (Ben Abdelmalek Ramdane, formerly named Ouillis) allowed a careful redescription of S. mauritanicus by means of biometric measurements and thorough analysis of the oral plate architecture of these topotypical samples. Two morphological types differing by the elongation of the test and the dimensions of the plastronal area are documented. Synonymy of nominal Schizobrissus species are discussed.

Since Schizobrissus mauritanicus is well defined, as well as its type locality, and given the ambiguities and disagreement of the scientific community on S. cruciatus, it is now appropriate to restore S. mauritanicus as the type species of the genus.