Micromorph brachiopods from the late Asbian (Mississippian, Visean) from northwest Ireland (Gleniff, County Sligo)

A diverse assemblage of minute brachiopods is reported from the Visean (late Asbian) Meenymore Formation exposed in the Gleniff outlier, County Sligo, northwest Ireland. The assemblage includes 14 micromorph species and juveniles of larger species, in which spire-hearers (Athyridida. Spiriferida and Spiriferinida) are the most diverse. Most of the species are left in open nomenclature as only few specimens show internal features. However, a new species of the uncommon orthotetide Drahanorhynchus (D. gleniffensis sp. nov.), previously known from the Mississippian of the Czech Republic, Spain and Germany, is described. In addition, the lectotype of the athyridide Hustedia nudtiplicata ((IC Koninck, 1887), from the Tournaisian of Tournai (Belgium) is selected and illustrated photographically for the first time. The brachiopods from Gleniff are associated with other small-sized benthic organisms particularly echinoderms and molluscs (gastropods, rostroconchs). The environmental factors, which lead to the small size, are not clearly understood although they probably included a combination of biological (e.g. food supply) and physicochemical (e.g. water oxygenation) parameters. Salinity is probably not implicated because brachiopods and echinoderms are generally stenohaline.