Strophomenid brachiopods from the Rhenish Lower Devonian (Germany) ULRICH JANSEN Early Devonian Strophomenida (Brachiopoda) from the Rhenish Slate Mountains (Germany) are described. Three gen- era are introduced as new: Gigastropheodonta [type species: Leptaena (Strophomena) gigas McCoy, 1852], Rheno- stropheodonta (type species: R. rhenana gen. nov. et sp. nov.) and Gibbodouvillina (type species: Strophomena taeniolata G. & F. Sandberger, 1856). The diagnosis of the poorly known genus Boucotstrophia Jahnke, 1981 (type spe- cies: Stropheodonta herculea Drevermann, 1904) is revised. These and several further taxa are briefly discussed with re- gard to phylogenetic relationships, palaeobiogeographical implications, palaeobiological aspects and stratigraphical sig- nificance. • Key words: Brachiopoda, Strophomenida, Devonian, Rhenish Slate Mountains, taxonomy, biostratigraphy, palaeobiology, palaeobiogeography. JANSEN, U. 2014. Strophomenid brachiopods from the Rhenish Lower Devonian (Germany). Bulletin of Geosciences 89(1), 113–136 (7 figures, 1 table). Czech Geological Survey, Prague, ISSN XXX. Manuscript received April 22, 2013, accepted in revised form July 19, 2013, published online December 17, 2013; issued January 21, 2014. Ulrich Jansen, Senckenberg Forschungsinstitut und Naturmuseum, Paläozoologie III, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany; [email protected] The Early Devonian Strophomenida from the Rhenish tion which ventral and dorsal valves belong to the same Slate Mountains (Rheinisches Schiefergebirge, Ger- species was not easy to answer in some cases. With regard many) have been paid little attention to since the classical to the genus Boucotstrophia Jahnke, 1981, common in the works of d’Archiac & de Verneuil (1842), G. & F. Sand- Seifen fauna, the author has come to the conclusion that its berger (1856) or Drevermann (1902, 1904). A few taxa type species B. herculea (Drevermann, 1904) was often have been studied more recently by Jahnke (1971, 1981, taxonomically united with or mistaken for the similar-sized 1986). In the frame of a large monograph on the “strophe- but unrelated “Stropheodonta” gigas (McCoy, 1852) odontoid” Strophomenida, Harper & Boucot (1978a–c) which occurs in the same fauna. In the opinion of the pres- revised all genera of this large group on a world-wide ent author, the genus Boucotstrophia has largely been mis- scale from the Ordovician to the Devonian. They intro- understood by previous workers starting with its original duced the genus Fascistropheodonta and the subgenus diagnosis (Jahnke 1981) and in the following years, for ex- Leptostrophia (Leptostrophiella) basing these on Rhe- ample by García-Alcalde (1992), Aït-Malek et al. (2000) nish type species, and they redescribed the Rhenish taxa and in the revised Treatise on Invertebrate Palaeontology, Douvillinella and Plicostropheodonta. Besides, several Part H (Cocks & Rong 2000). It was necessary to revise the Rhenish species were assigned by these workers to ge- genus and to erect a new genus for the group of “S.” gigas. nera established in regions outside the Rhenish Slate Another group of Rhenish strophomenids is repre- Mountains and partly from different stratigraphic levels, sented by Strophomena piligera G. & F. Sandberger, 1856. as well. The species has been reported from various stratigraphic The present author started his work on Rhenish “stro- levels within the Emsian of Europe and was assigned by pheodontoids” in the early nineties (Jansen 1994, 1998a, b) Harper & Boucot (1978c, p. 34) to Strophodonta Hall, focusing on materials from the classical localities Seifen 1850 whose type-species Strophomena demissa Conrad, (upper part of Middle Siegenian, Westerwald) and 1842 comes from the Middle Devonian Hamilton Group in Oberstadtfeld (upper part of Lower Emsian, Eifel area). E North America. Three years later, Jahnke (1981, pp. 152, The study of the Seifen fauna in particular has shown that 153) assigned S. piligera to the Rhenish genus Plico- intense collecting and detailed analysis of these multi-spe- stropheodonta Sokolskaya, 1960. The actual revision has cies allochthonous assemblages are necessary to record the shown that the taxon piligera actually includes at least two complete morphology of each taxon. Even the trivial ques- Rhenish species belonging to a new genus. DOI 10.3140/bull.geosci.1443 113 Bulletin of Geosciences Vol. 89, 1, 2014 Figure 1. Sketch map show- ing strophomenid localities in the Rhenish Slate Mountains (shaded in grey), Germany. The position of the map in Fig. 2 is indicated. Finally, the poorly known Rhenish species Strophomena of the lithostratigraphic units as used in the present work the taeniolata G. & F. Sandberger, 1856 is revised. Rösler Devonian Correlation Tables (Weddige 1996, 1998a, b, (1954) examined this species and determined it as a repre- 2000) and the “Stratigraphic Table of Germany” (German sentative of Strophodonta Hall, 1850. At that time, Stro- Stratigraphic Commission 2002) may be consulted. phodonta was still a comprehensive genus with very wide This work represents a part of a monographic revision scope. Later, Jahnke (1971) assigned it to the Bohemian ge- of the rhynchonelliformean brachiopod taxa from the nus Bojodouvillina Havlíček, 1967, and Harper & Boucot Rhenish Lower Devonian, with the intention to improve (1978b) finally included it in their new genus Proto- the knowledge on their morphology, to reconstruct their douvillina, which is based on a type species from the Hamil- phylogenetic relationships, to clarify their stratigraphic ton Group, again. Jahnke (1981, p. 157) determined Proto- ranges and to get new insights in their palaeobiology and douvillina taeniolata in the Armorican Massif and palaeobiogeography. García-Alcalde (1992, fig. 4) in the Cantabrian Mountains. The present author has compared the Rhenish forms with the presumable congenerics from North America to elucidate Material and methods their relationships. It turned out unavoidable to introduce a new genus for the species taeniolata and related forms. The materials studied are preserved as internal and external The classical regional stratigraphy, including the stages moulds of mainly disarticulated shells, rarely of articulated Siegenian and Emsian in German sense, is used herein ones. Latex casts were made to examine the external and in- (Carls 1987, Jansen 2001) because the global GSSP subdivi- ternal shell morphologies. The specimens were coated with sion still cannot be reproduced with satisfying precision in magnesium oxide prior to photographing. They are largely these siliciclastic-neritic, rhenotypic successions. In spite of stored in the Senckenberg Forschungsinstitut und Naturmu- this restriction, the strophomenids turned out to be excellent seum Frankfurt am Main (Senckenberg Museum), but in biostratigraphic markers on a regional scale. For the position other museums/institutions in Europe and overseas, as well. 114 Ulrich Jansen Strophomenid brachiopods from the Rhenish Lower Devonian Localities The localities are situated in different regions of the Rhe- nish Slate Mountains (Figs 1, 2) and further specified in the lists of materials. Abbreviations The lists of materials contain abbreviations used both for singular and plural: AVIM – internal mould of articulated valves; DVEM – external mould of dorsal valve; DVIM – internal mould of dorsal valve; DVIM+EM – internal mould of dorsal valve with corresponding external mould (counterpart); VVIM – internal mould of ventral valve; Figure 2. Strophomenid localities in the central Rhenish Slate Moun- VVEM – external mould of ventral valve; VVIM+EM – in- tains around Koblenz (Upper Emsian outcrops shaded in grey). ternal mould of ventral valve with corresponding external mould (counterpart). each side are either separated by a ridge as in Gigastrophe- odonta (Fig. 4K) or Rhenostropheodonta (Fig. 5J) [note Institutional abbreviations that the cavities are preserved as ridges and the separating ridge is represented by a furrow on the internal moulds fi- IPB – Paläontologisches Institut Bonn; MB.B. – Museum gured], or they are not separated as in Boucotstrophia für Naturkunde, Berlin, brachiopod collection; MW – Mu- (Fig. 3K). A taxonomic significance is ascribed to this seum Wiesbaden, G. & F. Sandberger collection; SMF – difference. The term “crural fossette” has been used to Senckenberg Museum, Frankfurt am Main; SMF-Mbg. – describe cavities receiving the posteroventral edge of the former collection of the Institut für Geologie und Paläonto- brachiophore or crural plate (Williams & Brunton 1997), logie, University of Marburg a.d. Lahn, today stored in the but this term refers to cavities in the hinge teeth. Senckenberg Museum, Frankfurt am Main; USNM – Smith- sonian, United States National Museum of Natural History, Interstriate. – Parvicostellate ornamentation consisting of Washington D.C., USA; YPM – Peabody Museum of Na- relatively coarser costellae clearly separating groups of tural History, Yale University, New Haven/Ct., USA. more or less numerous, uniform capillae (for example in Gibbodouvillina: Fig. 5D) or very fine costellae in a very regular pattern (= “interstriat” sensu Paeckelmann & Sie- Morphological terminology verts 1932, p. 41; = “interstriée” sensu Jahnke 1981, p. 149; Jahnke 1986, pp. 108–110; Aït-Malek et al. 2000, pp. 311, The terminology used in the systematic part largely follows 312, 315). The coarser costellae may arise from capillae in the Treatise on Invertebrate Paleontology,