Portrait

Description:

Portrait of the small caenomorphid ciliate, Ludio parvulus (Penard, 1922). The genus is monotypic. The colorless cell is roughly pyriform. The posterior end terminates in a short conical spinous projection. The pellicle is firm and only slightly deformable. The subequatorial peristome spirals around the body. The peristome is bordered anteriorly by a narrow perizonal ciliary stripe and also by an inconspicuous adoral zone of membranelles. The cytostome is at the posterior end of the peristome. A needle-like spine at least as long as the cell body arises on the right surface and extends posteriorly. A prominent cirrus approximately the same length as this spine trails behind the cell. A shorter anterior cirrus is not well seen in this image. The single spherical macronucleus is located eccentrically. The micronucleus is not clearly seen in these images. There is a single posterior contractile vacuole. L. parvulus is sapropelic. L. parvulus lacks the anterior rows of cirri seen in both Caenomorpha and Cirranter. Unlike Ludio, Cirranter lacks spines. Collected from a slow-moving freshwater stream near Boise, Idaho December 2004. DIC.