ECHINOSTOMA LUISREYI N. SP. (PLATYHELMINTHES: DIGENEA) BY LIGHT AND SCANNING ELECTRON MICROSCOPY

The entire life cycle of the Brazilian Echinostoma luisreyi n. sp., of the 37–collar spine E. revolutum group, has been observed under experimental conditions. The snail Physa marmorata serves as its first natural intermediate host. This species and the planorbid Biomplalaria glabrata act as experimental second intermediate hosts. The worm recovery rate was 51.3 and 0.6% for mice and hamsters, respectively, but the infection did not develop in the quail Coturnix coturnix. The natural vertebrate host is not known. The most important morphological character of the new species separating it from the other Echinostoma species studied is the oral corner spines that increase in size from the latero-oral to the ventro-oral regions. The ratio of the sizes of the smaller oral spines and the larger aboral ones was 1.7:1.0. Also, the excretory pore is radially wrinkled and dorsally subterminal. Images obtained by scanning electron microscopy confirmed the characters that differentiate the new species and the most closely related species.