Distribution extension of Escherbothrium molinae Berman and Brooks, 1994 (Cestoda: Tetraphyllidea: Triloculariidae) in Urotrygon sp. from the Pacific Coast of Mexico

Cestodes collected from the spiral valves of the stingray Urotrygon sp. from the Pacific coast of Mexico were identified as Escherbothrium molinae Berman and Brooks, 1994. The first report of the species was from the Gulf of Nicoya and the Guanacaste coast, Costa Rica; this work represents the second report of the species since the original description and extends its distribution north to Acapulco, Guerrero, Mexico.

Escherbothrium molinae was described by Berman and Brooks (1994) based on 35 specimens taken from several individuals of Urotrygon chilensis (Günther, 1871) (Chondrichthyes: Myliobatiformes: Urolophidae), the Chilean round ray, collected in the Gulf of Nicoya and the Guanacaste coast, Costa Rica. Since that date the species has been mentioned in publications by Brooks and Barriga (1995), Brooks et al. (1999), andCaira et al. (1999), among others, but it has not been reported again.
In the original work, Berman and Brooks (1994), established the genus and described E. molinae; the name of the genus was inspired by the artwork of M. C. Escher. They examined the holotype and paratypes of Zyxibothrium Hayden and Campbell, 1981 and illustrations of the scolex of Pentaloculum Alexander, 1963, and they noted a marked similarity between the scoleces of those Abstract: Cestodes collected from the spiral valves of the stingray Urotrygon sp. from the Pacific coast of Mexico were identified as Escherbothrium molinae Berman and Brooks, 1994. The first report of the species was from the Gulf of Nicoya and the Guanacaste coast, Costa Rica; this work represents the second report of the species since the original description and extends its distribution north to Acapulco, Guerrero, Mexico.
Francisco Zaragoza-Tapia 1 , Scott Monks 1* , Griselda Pulido-Flores 1 and Juan Violante-González 2 Distribution extension of Escherbothrium molinae Berman and Brooks, 1994 (Cestoda: Tetraphyllidea: Triloculariidae) in Urotrygon sp. from the Pacific Coast of Mexico taxa and the bifurcating structure of the medial bothridial septa of E. molinae. Therefore, they placed it into the family Triloculariidae. Others have suggested that the genus should be moved to the Rhinebothriinae, but formal taxonomic studies of this question are still wanting.
To date, the only known species of Escherbothrium is a parasite of elasmobranchs, Urotrygon sp. It has a singular type of scolex with 4 pedicellated bothridia, cup-shaped bothridia, each bothridium with apical sucker and muscular septa dividing it into 4 large and 2 small loculi (Figures 1-2). The specimens we collected conform to the description established by Berman and Brooks (1994) in this and the other features included in their description; Figures 1-2 are provided to aid in the identification of specimens.
The most often overlooked components of the biodiversity of a country are those organisms with life cycles as parasites. Unless there are health-related problems with particular species (Poulin 2004;Brooks and Hoberg 2008), only specialists are concerned about their presence or the possibility of their extinction; it is doubtful if a species of parasite will ever make the "Red List" (IUCN 2012). This is partly because the public sees parasites as diseases that must be cured rather than an indispensable part of natural systems (Brooks and McLennan 2002). This lack of emphasis has resulted in there being few reports of their distributions except in the specialized literature, and many helminths have only been reported in the original descriptions. Despite the usefulness of distribution records of parasites to our understanding of the ecology and evolution of parasites and their hosts (Brooks and McLennan 1993;Brooks and Hoberg 2000;Poulin 1999), this trend has yet to be reversed. This report of the range extension of Escherbothrium molinae Berman and Brooks, 1994 is offered to provide information useful for those classes of studies.
Finally, the finding of E. molinae in Guerrero and Jalisco, suggests that individuals of U. chilensis are moving (possibly migrating) within the limits of the range of   -Pérez 1996;Fishbase 2012). From this second report, and the distance between each known locality, it is obvious that further studies must be carried out for a fuller understanding of the distribution of E. molinae, particularly in the localities between Mexico and Costa Rica. Molecular studies could shed light on this hypothesis and provide information about the potential "passive migration" of E. molinae. The stingrays should also be studied with the same goal. The taxa from Mexico that are host for E. molinae are difficult to distinguish and assign to a particular species. Both U. chilensis (Günther, 1872) and U. rogersi (Jordan and Starks, 1895) are common along this coast, and there are occasional reports of U. nana Miyake andMcEachran, 1988 (see Castro-Aguirre andEspinosa-Pérez 1996). The morphology (i.e., coloration, etc.) of these species is variable and each is virtually indistinguishable to casual observation; assignment to species is based primarily on the form of the pupil cover of the eye (McEachran 1995;Fishbase 2012). Thus, we are relatively sure that the stingrays collected in Mexico are either U. chilensis or U. rogersi (or both species were included), but we cannot be sure beyond assigning them to Urotrygon sp. Both parasitological and ichthyological knowledge would benefit from a thorough study of this genus that would correlate morphology and molecular identification.