COLACIUM LIBELLAE SP. NOV. (EUGLENOPHYCEAE), A PHOTOSYNTHETIC INHABITANT OF THE LARVAL DAMSELFLY RECTUM1

Colacium libellae sp. nov., in the non-flagellated palmella stage and lacking stalks, lines the cuticle of the rectum of damselfly larvae, forming a conspicuous green plug. In culture this species forms highly-branched colonies of stalked cells. The cells tire often elongated to twice the size of most motile cells (40–50 × 6–10 μm), with parallel sides and rounded apices. These features are distinctive when comparisons are made among clones of related species in soil-water-pea medium. C. libellae established itself in the rectum of previously Colacium-free larvae of the damsel fly Anomalagrion hastatum whereas a clone of C. vesiculosum and C. mucronatum did not.