New find of Dactylophrya-stage of parasitic suctorian of genus Tachyblaston Martin, 1909 (Ciliophora, Suctorea) with comments on genus taxonomy Author Chatterjee, Tapas Near Hari Mandir Road, Hirapur, Dhanbad 826004, Jharkhand, India Author Dovgal, Igor A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, 2, Nakhimov ave., Sevastopol, 299011, Russia Author Sautya, Sabyasachi Laboratory for Benthic Ecological Trait Analysis (L-BETA), Biological Oceanography Division, CSIR-National Institute of Oceanography, Regional Centre, Mumbai - 400053, India text Zootaxa 2023 2023-12-19 5389 2 266 274 https://www.mapress.com/zt/article/download/zootaxa.5389.2.8/52515 journal article 10.11646/zootaxa.5389.2.8 1175-5326 10406684 682D659F-A0BD-4D81-88A9-3250E6B3A3FB Tachyblaston reversum ( Collin, 1909 ) n. comb. = Ophryodendron reversum Collin, 1909 , syn. n. = Pleurophryodendron reversum ( Collin, 1909 ) , syn. n. Diagnosis (based on Collin 1909 , 1912 , and own data): Marine suctorian ciliate, the Dactylophrya -stage of which has unflattened pyramidal or pear-shaped cell body, covered by extremely thin, transparent lorica, aperture of which have noticeable lateral clefts ( Fig. 2A–D ; Fig. 3A, B ; Fig. 5C ). There are spherical of oval macronucleus, micronuclei not observed. Up to 8 unciliary larval stages (dactylozoites) form at apical surface of the body. Dactylozoites ( Fig. 3A, B ; Fig. 5C ) are spindle-like, with sharp anterior and rounded dorsal ends. The anterior end with feeble marked knob. Macronucleus of dactylozoit, rounded, centrally located. There are from 1 to 2 large contractile vacuole, positioned above macronucleus. Reproduction is by semi-internal successive vermigemmy. The trophont stage unknown. Measurements ( in µm, based on one individual in present find): Lorica length 265; lorica width 122; stalk length 101; stalk width 17. Measurements of dactylozoites (in µm, based on three individuals in present find): cell-body length 103– 119, width 27–36; dimensions of macronucleus 15–18×10–13; contractile vacuole dimensions 20–23×26–30. Localization: Abdomen segments and furca of a harpacticoid host. Type locality: Sète , France . Type host: Ameira sp. The host of trophont stage unknown.