Description of Opisthonecta matiensis n. sp (Protozoa, Ciliophora), a new peritrich ciliate from wastewater

Opisthonecta matiensis n. sp. was isolated from the inlet water of a wastew ater treatment plant near Madrid, Spain, and studied in vivo, with silver m ethods, and using electronic and indirect immunofluorescence microscopy. Th is new species shows an amphora-like cell shape and has a size of 45-73 mu m ((x) over bar 58.2) X 25-40 mu m ((x) over bar 31.3). The oral infracilia ture is formed by one haplokinety, three polykineties, and a short row of k inetosomes (epistomial membrane). The aboral infraciliature is made up of t he trochal band and the scopula. From the trochal band arise three fibrilla r systems: oral fibers, aboral fibers, and oblique fibers. The myoneme syst em is composed of a delicate peristomial ring, longitudinal branched fibers that reach the trochal band and of radial fibers extending from the scopul a to the trochal band. The silverline system consists of an average of 147 lines. This new species is separated from other known forms by its smaller size, the presence of one single vacuole, and its higher number of silverli nes.