A Walcottella-like bradoriid (Arthropoda) from the lower Cambrian of Sweden

A probable new bradoriid genus and species, represented by a single specimen, is described tentatively as Walcottella? aff. apicalis Ulrich & Bassler from lower Cambrian strata of Sweden. The specimen comes from the Bergmyrhobben section west of Storuman in Västerbotten County, northern Sweden. It was found in mudstone in the lower part of the Grammajukku Formation, co-occurring with a rich acritarch assemblage of the Skiagia ornata-Fimbriaglomerella membranacea acritarch Zone that corresponds to the Schmidtiellus trilobite Zone. The specimen represents one of the oldest bradoriids known from the paleocontinent Baltica. Characteristics of the specimen are a dorsomedian to mid-dorsal acuminate nod and a flattened shell border along the free margin, the latter feature unknown from other bradoriid taxa. The specimen occurs at the same level where the first trilobites were found in the investigated section. The biogeographic affinities of the Baltic bradoriid genera to the bradoriid fauna of Avalonia, western Gondwana and Laurentia are reviewed and discussed.