Caddisfly (Insecta: Trichoptera) Diversity in the Ozarks and Tallgrass Prairie Transitional Zone, Arkansas and Missouri, USA

ABSTRACT Adult caddisfly (Trichoptera) community assemblages were studied in nine streams located in the transitional zone of the Ozarks and tallgrass prairie ecoregions. Seventy-two species, 36 genera, and 15 families were collected from among these streams. Cluster analysis showed taxa similarity among sites was grouped by geographic proximity rather than stream type, but, within the primary clusters, there also was separation among the streams. Predominantly spring-fed streams were less closely related to the other streams in those clusters. Among streams within a park, there were distinct differences among their respective faunas, which is likely due to local physical and chemical differences in those streams. An NMDS analysis was consistent with the similarity analysis with streams ordinating primarily based on geographic proximity (stress = 0.07, R2 = 0.76) and not stream type (multiresponse permutation procedure: A = 0.289, p = 0.003). Results from free permutation testing showed half of the environmental variables included in the model were significant (p ≤ 0.05). The most important findings of this study are that highest taxa similarities were among streams in the same park (local scale) as opposed to similar stream types among parks (regional scale), but there also was substantial variation among stream types within parks due to local factors.