Comparative Study of the Tegumental Surface of Several Species of Gorgoderina Looss, 1902 (Digenea: Gorgoderidae), as Revealed by Scanning Electron Microscopy ROSARIO MATA-LO ´ PEZ AND VIRGINIA LEO ´ N-RE ` GAGNON 1 Departamento de Zoologı ´a, Instituto de Biologı ´a, Universidad Nacional Auto ´noma de Mexico, Apartado Postal 70-153, C.P. 04510, Mexico, Distrito Federal, Mexico ABSTRACT: Seven species representing Gorgoderidae Looss, 1899, previously have been examined by scanning electron microscopy. This study describes the papillary pattern on the body surface of 6 additional species—Gorgoderina attenuata, Gorgoderina bilobata, Gorgoderina diaster, Gorgoderina megalorchis, Gorgoderina parvicava, and Gorgoderina megacetabularis—from localities in the United States, Mexico, and Costa Rica. Four types of papillae (button, ciliated, rosette, and domed) were distinguished on the body surfaces of these trematodes and both the type and position of papillae varied among species. A consistent papillary pattern on the ventral forebody region and oral and ventral suckers is described. Three constant pairs of button papillae are around the stylet cavity. The pattern on the oral sucker consists of 10 papillae around the oral aperture. One of these pairs was doubled in G. bilobata and G. diaster; in addition, a variable number of papillae arranged in groups were usually present. Five pairs of button papillae were always present in a lateral position on the ventral surface of the forebody between both suckers. Six rosette papillae were observed on the ring of the ventral sucker, except in G. megacetabularis; 4 additional pairs of rosette papillae and 2 pairs of domed papillae were observed on the internal surface of this sucker. These papillae were not observed in G. bilobata and G. parvicava. Differences in the papillary pattern among species lie in the position of the different types of papillae. KEY WORDS: Digenea, Gorgoderidae, Gorgoderina attenuata, Gorgoderina bilobata, Gorgoderina diaster, Gorgoderina megalorchis, Gorgoderina parvicava, Gorgoderina megacetabularis, Mexico, Costa Rica, United States, scanning electron microscopy. Scanning electron microscopy (SEM) has become increasingly useful in describing the surface topog- raphy of helminth parasites, and many species of digenetic trematodes have been examined by this method. Recent ultrastructural studies of the body surface of adults, miracidia, and cercariae of digenetic trematodes have revealed a variety of sensory receptors (Thulin, 1980; Fried and Fujino, 1984; Sobhon et al., 1986; Tandon and Maitra, 1987; Busta and Nasincova, 1988; Cifrian and Garcı ´a-Corrales, 1988; Zdarska et al., 1988; Ferrer et al., 1996). More detailed studies on the presence, microtopography, and distribution of the tegumental papillae also have been performed (Nadakavukaren and Nollen, 1975; Edwards et al., 1977; Bakke and Lien, 1978; Fujino et al., 1979; Hoole and Mitchell, 1981; Cribb, 1987; Bakke and Hoole, 1988; Abdul-Salam et al., 2000; Moravec, 2002). However, within the Family Gorgo- deridae Looss, 1899, only Gorgoderina sp.; Gorgo- derina attenuata (Stafford, 1902) Stafford, 1905; Gorgoderina vitelliloba (Olsson, 1876) Ssinitzin, 1905; Phyllodistomum conostomum Olsson, 1876; Phyllodistomum folium (Olfers, 1816) Braun, 1899; and Phyllodistomum umblae Fabricius, 1780 have been subjects of SEM studies of tegumental surface microtopography (Nadakavukaren and Nollen, 1975; Bakke and Lien, 1978; Hoole and Mitchell, 1981; Hoole et al., 1983; Bakke and Zdarska, 1985; Bakke and Bailey, 1987; Bakke and Hoole, 1988). The papillary pattern seems to remain constant during development (Goodchild, 1943; Thomas, 1958), but it has been described in detail for only 4 gorgoderid species: Phyllodistomum simile Nybelin, 1926, and Gorgodera amplicava Looss, 1899, by light micros- copy and G. vitelliloba and Gorgoderina megaceta- bularis Mata-Lo ´pez, Leo ´n-Re `gagnon and Brooks, 2005, by SEM (Goodchild, 1943; Thomas, 1958; Bakke and Hoole, 1988; Mata-Lo ´pez et al., 2005). This study describes the types of papillae and the distinct papillary pattern observed on the ventral forebody region and oral and ventral suckers in 6 species of Gorgoderina. MATERIALS AND METHODS Adult gorgoderids were collected from the urinary bladder of naturally infected amphibians as follows (number of specimens examined by light microscopy/number of specimens examined by SEM presented parenthetically by species): G. attenuata (6/6), Pawnee Lake, Lancaster County, Nebraska, U.S.A., ex. Rana catesbeiana Shaw, 1802, and 1 Corresponding author (e-mail: vleon@ibiologia. unam.mx). Comp. Parasitol. 73(1), 2006, pp. 24–34 24