BULLETIN DE L’INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN SCIENCES DE LA TERRE, 78: 9-29, 2008 AARDWETENSCHAPPEN, 78: 9-29, 2008 Devonian Proetidae (Trilobita) from the Ardennes Massif (Belgium, N France) and the Eifel Hills (W Germany) by Allart P. VAN VIERSEN & Harald PRESCHER VIERSEN, A.P. VAN & PRESCHER, H., 2008 – Devonian Proetidae (Trilobita) from the Ardennes Massif (Belgium, N France) and the Eifel Hills (W Germany). In: STEURBAUT, E., JAGT, J.W.M. & JAGT- Y AZYKOVA, E.A. (Editors), Annie V. Dhondt Memorial Volume. Bulletin de l’Institut royal des Sciences naturelles de Belgique, Sciences de la Terre, 78: 9-29, 5 igs, 5 pls, Brussels, October 31, 2008 – ISSN 0374-6291. Abstract New data are presented on trilobites of the family Proetidae (subfamilies Proetinae, Dechenellinae, Cornuproetinae) from the Devonian of the Ardennes Massif and the Eifel Hills (Rhenohercynian zone). Preliminary stratigraphic distributions of the Proetidae from the southern border of the Dinant Synclinorium are introduced. Eight taxa are recorded, namely: Gerastos prox lessensis n. ssp., Gerastos catervus (VAN VIERSEN, 2006), Gerastos sp. B, Dohmiella tenuiornata n. sp., Dechenella daumeriesi n. sp., Dechenella sp. A, Cornuproetus cornutus ssp. 2, and Diademaproetus? sp. In addition, Dohmiella stumporum n. sp. and Gerastos sp. A are described from the Eifel. The genus Rhenocynproetus BASSE, 2002 is regarded as a junior subjective synonym of Gerastos GOLDFUSS, 1843. Keywords: Trilobites, Proetidae, Devonian, Ardennes, Eifel. Résumé De nouvelles données sont présentées sur les trilobites de la famille des Proetidae (sous-familles des Proetinae, des Dechenellinae et des Cornuproetinae) du Dévonien du Massif des Ardennes et des collines de l’Eifel (zone rhéno-hercynienne). Une distribution stratigraphique préliminaire des Proetidae sur le bord méridional du Synclinorium de Dinant est proposée. Huit taxa sont reconnus, à savoir Gerastos prox lessensis n. ssp., Gerastos catervus (VAN VIERSEN, 2006), Gerastos sp. B, Dohmiella tenuiornata n. sp., Dechenella daumeriesi n. sp., Dechenella sp. A, Cornuproetus cornutus ssp. 2 et Diademaproetus? sp. En complément, Dohmiella stumporum n. sp. et Gerastos sp. A sont décrites dans la région de l’Eifel. Le genre Rhenocynproetus BASSE, 2002 est considéré comme un synonyme plus récent de Gerastos GOLDFUSS, 1843. Mots-clefs: Trilobites, Proetidae, Dévonien, Ardennes, Eifel. Introduction The family Proetidae (proetids) encompasses a large group of trilobites in the Devonian of the Ardennes. Early Devonian trilobite faunas in this region are low in diversity, and dominated by the families Acastidae and Homalonotidae. The appearance of Proetidae during the Middle Devonian here is relatively late when compared to abundant Early Devonian occurrences elsewhere, e.g. in Bohemia (ŠNAJDR, 1980) and Morocco (ALBERTI, 1969). In the Ardennes, the stratigraphically earliest conirmed records of Proetidae come from the lower Eifelian (Couvin and Jemelle Formations), which more or less coincides with putative initial migration of trilobites from Gondwana towards the northern margin of the Rheic Ocean (SCHRAUT & FEIST, 2004) and the development of shallow-water carbonate deposition in the Ardennes (CRÔNIER & VAN VIERSEN, 2007). Claimed occurrences of proetids in the upper Emsian of Belgium (e.g. MAILLIEUX, 1933; ASSELBERGHS, 1946) have not been conirmed but are possible given that they were recently reported from upper Emsian strata in adjacent regions (e.g. Proetinae and Cornuproetinae from Luxembourg by BASSE, 2002 and BASSE & FRANKE, 2006). Throughout the Eifelian, family Proetidae is represented in the Ardennes by a substantial variety of species comprising at least six genera (Fig. 1). Diversity of the family declined signiicantly in this region at around the Eifelian–Givetian boundary while only Gerastos and Dechenella are known with certainty to continue into the Givetian. The proetid fauna of the Devonian of the Ardennes has been documented inadequately which is due mainly to a 60-year intermission of research on Devonian trilobites there. Although occurrences of proetids are frequently reported in the older literature (e.g. MAILLIEUX, 1904, 1919, 1933, 1938; RICHTER &