Populations that are associated with S. sempervirens in Maine and Massachusetts... and with S. bicolor in Virginia... were studied in detail in the present work, and although we did not find morphological differences between them and A. monacha, our molecular analysis suggests that they belong to at least two undescribed species. These species are not described here because additional molecular data are needed in order to determine their boundaries and host associations. Their galls are locally common and appear similar in structure to those of A. monacha.
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One individual from a rosette gall on S. uliginosa is also included in the sempervirens/bicolor clade, whereas another individual from this host grouped with A. monacha, suggesting that S. uliginosa is used by two different species.

[Please refer to this paper for many more details of gall biology, insect life history, anatomy, and phylogeny. This gallformers entry is meant to represent the gall that sorted away from the A. monacha clade in their phylogenetic analysis.]