Comparative morphology of the scolices and microtriches among five species of Tetrabothrius (Eucestoda: Tetrabothriidae).

The structure of the scolex, neck, and adjacent strobila of 5 species of Tetrabothrius was evaluated using low to high magnification scanning electron microscopy. Species-specific patterns and morphotypes (spiniform, papilliform, and filiform) of microtriches were found on the scolices and strobilar tegument of Tetrabothrius (Oriana) affinis, Tetrabothrius (Oriana) filiformis, and Tetrabothrius (Culmenamniculus) laccocephalus ; microtriches were absent in Tetrabothrius (Culmenamniculus) cylindraceus and Tetrabothrius (Tetrabothrius) sp. The presence, distribution, and form of microtriches may not be correlated with the subgeneric divisions of Tetrabothrius or the host taxon. Unique patterns do not appear to be shared with other groups of cestodes, particularly other tetraphyllideans. We suggest that the spiniform, filiform, and papilliform types of microtriches may be symplesiomorphic for the Eucestoda.