MORPHOLOGY, DISTRIBUTION, LIFE HABITS AND PHYLOGENETIC AFFINITIES OF THE RECENT BRACHIOPOD GWYNIA-CAPSULA (JEFFREYS)

For more than a century, the Recent micromorphic trocholophous brachio pod Gwynia capsula (JEFFREYS) has remained inadequately understood. In this paper we provide new information on its life habits and geograph ic distribution and present a revised morphological description which corrects inaccuracies in various descriptions of the species. We also note the suppression of punctation in four specimens of G. capsula in an otherwise morphologically normal population from Connemara, fire. W e reject past suggestions by some authors that Gwynia may represent th e juvenile stage of some other brachiopod. G. capsula is compared to t he diminutive Recent brachiopod Argyrotheca cistellula (SEARLES-WOOD), with which it often occurs, and also with the Middle Jurassic micromo rph Zellania davidsoni MOORE. On the basis of a morphological comparis on between Gwynia and Zellania, a case is made for considering Gwynia as a paedomorphic descendant of Zellania, notwithstanding the consider able time gap separating the two forms. Their systematic positions wit h respect to other terebratulide genera have, however, yet to be resol ved.