Infraciliature and systematic position of the marine interstitial ciliates (Protozoa, Ciliophora) Lopezoterenia torpens (Kahl, 1931) nov. gen., nov. comb., Discotricha papillifera Tuffrau, 1954, and Paraspathidium fuscum (Kahl, 1928) Fjeld, 1955. Revista de la Sociedad Mexicana de Historia Natural, 47 1997: 41-63. 59 [Zoological Record Volume 136]