Abstract

Three new species of plumatellid (Phylactolaemata) bryozoans are distinguished largely by the presence of tiny, rash-like nodules on the floatoblast surface. Nodules are integral parts of the sclerotized floatoblast envelope, and they persist through generations of laboratory rearing. These minute structures are best detected by scanning electron microscopy. In Plumatella bushnelli, n. sp., nodules are densely distributed on the floatoblast annulus. Notable in this species are floatoblast dimensions: the dorsal fenestra measures >½ the overall length of 400 μm. The species is known only from single sites in North Carolina and New Zealand. Plumatella nodulosa, n. sp., bears nodules over the entire floatoblast surface, not just the annulus; otherwise, the species most resembles the widespread P. rugosa (Wood, Wood, Geimer, Massard, 1998). Plumatella nodulosa is reported from 5 lentic sites in Illinois, Ohio, and western New York. In Plumatella similirepens, n. sp., the floatoblast has a paved annulus with widely scattered nodules; unlike the European species, P. repens (L., 1758), the floatoblast suture lacks the row of prominent tubercles on either side. Plumatella similirepens is confirmed from 2 sites in Illinois. Contrary to numerous published works, P. repens is unknown in North America.[Romanized Abstract]Three new species of plumatellid (Phylactolaemata) bryozoans are distinguished largely by the presence of tiny, rash-like nodules on the floatoblast surface. Nodules are integral parts of the sclerotized floatoblast envelope, and they persist through generations of laboratory rearing. These minute structures are best detected by scanning electron microscopy. In Plumatella bushnelli, n. sp., nodules are densely distributed on the floatoblast annulus. Notable in this species are floatoblast dimensions: the dorsal fenestra measures > 1/2 the overall length of 400 mm. The species is known only from single sites in North Carolina and New Zealand. Plumatella nodulosa, n. sp., bears nodules over the entire floatoblast surface, not just the annulus; otherwise, the species most resembles the widespread P. rugosa (Wood, Wood, Geimer, Massard, 1998). Plumatella nodulosa is reported from 5 lentic sites in Illinois, Ohio, and western New York. In Plumatella similirepens, n. sp., the floatoblast has a paved annulus with widely scattered nodules; unlike the European species, P. repens (L., 1758), the floatoblast suture lacks the row of prominent tubercles on either side. Plumatella similirepens is confirmed from 2 sites in Illinois. Contrary to numerous published works, P. repens is unknown in North America.