Exostome striate

Taxonomic recognition does not just depend on broad character states of exostome papillose or exostome striate. Within these categories, there are often subtle differences in ornamentation... 

Ornamentation of the dorsal plates in the basal third of the exostome teeth conspicuously striate (striae set with papillae or not) state 1 smooth, papillose, or weakly striate near the tooth base state 2. 

Interpretation of the range of ornamental patterns found within the family as currently recognized is also problematic. Are these ancestral states that predate the evolution of reduction Given the complexity of the internal anatomy of the striate and papillose exostomes, it is tempting to consider these as ancestral. The alternative hypothesis that the peristome evolved the reduced state and concurrently or subsequently evolved these different ornamental patterns together with the marked internal differentiation seems contradictory. 

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