2c and d). Tang and Tang

(1977) reported that each larva develops a proboscis-like portion at the anterior end. The same structure was observed in the present study (Fig. 2a, b and f). This larval stage did not present oral aperture. Thus, the hollow find more tapered end is named anterior end, and the elongated end the posterior region. In the tapered region are concentrated the cercariae in development tightly packed by an inner tegument highly folded, named endocyst, which was already separated from the external sac, when dissected sporocysts were observed (Fig. 2 and Fig. 3). The external surface of the tegument was folded presenting well defined transversal and concentrical striations at the anterior end of the larval body (Fig. 3b, c and d). These striations ended in a blind cavity at the hollow tapered region (Fig. 2e and f). When observed by SEM the tegument showed striations that were interrupted by longitudinal

striations, which were more conspicuous at the anterior end of the body (Fig. 3c, d and e). This hollow region presented a granular and dense aspect with dark appearance under the LM (Fig. 3a). When expelled, the sporocyst had a whitish color in the center of the body and was transparent at both ends (Fig. 3f) and had a total length of 5.280 mm (4.450–5.950 mm). As described before for E. pancreaticum ( Tang, 1950), E. coelomaticum sporocysts also have a transparent oval sac-like region. The middle of the body was swollen, exhibiting a round or oval sac-like shape; the anterior terminal portion had a short prolongation click here as one filament, and the posterior region a longer filament-like prolongation ( Fig. 3g). This swollen region measured about 1.287 mm (1.000–1.500 mm) in length and 0.095 mm (0.700–1.400 mm) in width. The anterior filament was 0.712 mm (0.0425–0.0950 mm)

in length and the posterior filament was larger than the anterior one, 3.250 mm (2.450–3.775) in length. The point of origin of the anterior and posterior filaments is viewed in Fig. 3h and i, respectively. The tegument of the larvae presents many foldings with different orientations ( Fig. 3j). Looss (1907) redescribed D. coelomaticum and proposed the new genus Eurytrema based only in characters observed in the adult worm. Only in 1977, Tang and Tang included in their study Etomidate characteristics of the larval stages of E. coelomaticum, such as morphometrical description of the intramolluscan larval development. Since then, the morphology of the E. coelomaticum intramolluscan larval stages was forgotten. Beyond this, they reported some biological and epidemiological aspects of Eurytrema species, presenting some characteristics of E. coelomaticum, but they focused only on morphometrical characters and the images were presented as drawings. This lack of information leads us to describe in this work the morphology and characteristics of the larval stages of E. coelomaticum and to compare it with data on the morphology of E.