Samantha A. Seixas

Temnocephala lutzi Monticelli (Platyhelminthes, Temnocephalida) ectosimbionte sobre duas espécies de Trichodactylus Latreille (Crustacea, Decapoda, Trichodactylidae) da região sul do Brasil

Temnocephala lutzi Monticelli, 1913, ectosymbiont on brachyuran freshwater crabs of the genus Trichodactylus Latreille, 1828 is recorded for the first time in the State of Rio Grande do Sul, southern Brazil. Two hundred and seventy-nine crabs of two species were examined: 211 Trichodactylus panoplus (von Martens, 1869) and 68 Trichodactylus fluviatilis Latreille, 1828 of which 51 (24.17%) and 28 (41.17%) were positive for T. lutzi, respectively. Crabs of both species carried eggs fixed, exclusively, on the floor of the branchial chambers and/or on the lower side of the gills. Adult as well as young specimens were found inside and outside the branchial chambers. The temnocephalans were always devoid of body pigmentation, although they kept the red eye pigment undiluted in specimens fixed by formalin. The cirrus of T. lutzi showed the typical shape for the species, while the dorsolateral, post tentacular ‘excretory’ syncytial plates, demonstrated by two special techniques (silver nitrate staining and SEM), appeared with an elliptical shape and a central nephridiopore.