Diversity of the Schizophoria lineage (Brachiopoda: Orthida) in the Lower and Middle Devonian of Poland and adjacent areas

The nominative subgenus of Schizophoria (Brachiopoda, Orthida) is represented in the Lower and Middle Devonian of Poland and of the western Ukraine by six taxa: late Emsian Schizophoria (S.) interstrialis, late Eifelian S. (S.) schnuri biscissa, early Givetian S. (S.) schnuri schnuri, middle to late Givetian S. (S.) schnuri prohibita ssp.n., middle Givetian S. (S.) parvaepunctata and late Givetian S. (S.) sp.n. (unnamed for lack of sufficient material). Morphotypes referable to S. (S.) schnuri biscissa and to S. (S.) schnuri junkerbergiana co-occur in the same outcrop (not necessarily in the same levels), wherefore the separation of these subspecies may be maintained only if they are considered as chronosubspecies (unverifiable on the studied material) but not as geographic variants (hypothesis falsified by the studied material). A lectotype for S. (S.) interstrialis and a neotype for S. (S.) parvaepunctata are selected. Punctae diameter and density (either an important systematic character according to some authors or devoid of such value according to other ones) were investigated: they show important within-individual and within-sample variation, wherefore they cannot serve to distinguish related species. On the contrary, punctae character combinations are sufficiently constant to help differentiate subgenera or groups of species. In the studied material, three clusters are distinguished on the basis of the punctae characteristics: S. (Pachyschizophoria) and S. (S.) parvaepunctata differ between each other and from all other investigated species of S. (Schizophoria); the latter are indistinguishable on the sole basis of punctae characteristics.