First report of Temnocephala haswelli (Platyhelminthes: Temnocephalida) in Pomacea canaliculata (Mollusca: Ampullariidae) from Brazil: description update based on specimens from the state of Rio Grande do Sul, Brazil

Abstract

The impact of the discovery of Temnocephala haswelli Ponce de Léon, 1989, described as ectosymbionts of ampullariid apple snails outside of Uruguay, motivated us to collect a large number of specimens of Pomacea canaliculata (Lamarck, 1822) from several localities in the southern portion of the state of Rio Grande do Sul. This species was recorded three times after its description: in a study of chromosomes, in a study about the ultrastructure of the collar receptor cells, and in a study of the Haswell glands, all conducted in Uruguay. A total of 301 specimens of P. canaliculata were collected from 1999 to 2007. Temnocephalans found in the pallial cavity were identified as T. haswelli, which occurred in single infestations or concurrently with Temnocephala iheringi Haswell, 1893. Helminths usually showed a light-orange body pigmentation and conspicuous, intense red-eye pigment. Many taxonomic characters evidenced by several techniques were documented photographically for the first time. The typical curved cirrus, approximately 90°, typical of the species, showed some variation in the width of the shaft base, whereas the first longitudinal row of spines of the introvert appeared with shorter spines. The vagina was found to be thick-walled, but not very muscular, and to have a single, large and slightly asymmetrical sphincter, with the posterior portion of slightly larger diameter. Eggs were observed in the umbilicus and along the suture, but predominantly in the body whorl of the shell. Egg peduncles were found to be very short or, most of the time, the eggs were sessile, always with a long apical filament. The rounded shape of the dorsolateral 'excretory' syncytial epidermal plates had external margins reaching the ventrolateral region of the body and eccentric nephridiopores. This is the first record of the species outside Uruguay and in Brazil

First report of Temnocephala rochensis (Platyhelminthes: Temnocephalida) from Pomacea canaliculata (Mollusca: Ampullariidae) outside Uruguay: description update based on specimens from the state of Rio Grande do Sul, Brazil

“…Although there is a series of differences when the specimens from Rio Grande do Sul are compared with the specimens previously described, a number of other characters agree with the original description by PONCE DE LEÓN (1979), particularly in regards to the morphology of the cirrus, the character with the highest taxonomical value, plus the distribution of the rhabditogen glands and the peculiarities of the female reproductive system. Despite extended sampling efforts in the eastern region of Rio Grande do Sul (collections of P. canaliculata referred in SEIXAS et al 2010a and2010b for the study about T. iheringi and T. haswelli, respectively), T. rochensis was found to be restricted to the southern region of the State, close to Laguna Negra, Uruguay.…”