Microconchid tubeworms from the Jurassic of England and France

The Bajocian tubeworm Spirorbis midfordensis, previously regarded as a spirorbid polychaete, is reinterpreted as a microconchid and assigned to Punctaconchus gen. nov. along with two new species, Punctaconchus ampliporus sp. nov. (Toarcian?, Aalenian–Bathonian), the type species of the new genus, and Punctaconchus palmeri sp. nov. (Bathonian). Microconchids are a mostly Palaeozoic group of tubeworms that are probably more closely related to modern lopho− phorate phyla than they are to polychaetes. Punctaconchus, the youngest unequivocal microconchid, is characterised by having large pores (punctae) penetrating the tube wall, which has a fibrous or platy lamellar microstructure, and ripplemark−like transverse ridges on the tube interior. In both morphology and ecology it is a remarkable homeomorph of the polychaete Spirorbis.