Comparative Parasitology 68(2) 2001 - Peru State College

da-Lopez et al., 1985; Leon, 1992; Jimenez-
Garcia, 1994; Salgado-Maldonado et al., 1997)
did not reveal a rich fauna of cestodes (but see
Scholz et al., 1996). Monogeneans have only exceptionally
been reported from freshwater fishes
in Mexico (Lamothe-Argumedo, 1981), but a
number of species have been found recently, in
particular in southeastern Mexico (Kritsky et al.,
1994, 2000; Mendoza-Franco et al., 1997,
1999).
Most of the parasites recorded in this survey
are shared with freshwater fishes inhabiting other
Mexican drainage basins (see Pineda-Lopez
et al., 1985; Jimenez-Garcia, 1994; Moravec,
Vivas-Rodriguez, Scholz, Vargas-Vazquez,
Mendoza-Franco, and Gonzalez-Soli's, 1995;
Moravec, Vivas-Rodriguez, Scholz, Vargas-Vazquez,
Mendoza-Franco, Schmitter-Soto, and
Gonzalez-Soli's, 1995; Scholz et al., 1995, 1996;
Salgado-Maldonado et al., 1997; Moravec,
1998; Moravec et al., 2000; Scholz and Vargas-
Vazquez, 1998; Scholz and Salgado-Maldonado,
2000). Six adult species are of neotropical origin:
Urocleidoid.es cf. costaricensis, M. simplex,
R. kidderi, R. lichtenfelsi, R. mexicana, and N.
golvani. Saccocoelioides sogandaresi, Rhabdochona
canadensis, and C. cyprinodonticola have
been recorded in various freshwater fishes in
Canada and southern North America (Lumsden,
1963; Moravec and Aral, 1971; Moravec, 1998).
Twelve of 25 helminth species recorded during
this survey were larval forms that utilized
small freshwater fishes as intermediate hosts. All
these allogenic species are widespread taxa, with
wide distributions within Mexico and broad host
specificity. Thus, they can be regarded as an
ecological component of the fish parasite communities
in the Balsas River basin. The metacercariae
of C. complanatum, P. minimum, and
Diplostomum cf. compactum, as well as the larvae
of nematodes Eustrongylides sp., Contracaecum
sp., and Acuariidae gen. sp. have been
commonly recorded in cichlids, poeciliids, characiids,
pimelodids, and other fish families from
southern Mexico (Pineda-Lopez, 1985; Pineda-
Lopez et al., 1985; Osorio-Sarabia et al., 1987;
Jimenez-Garcia, 1994; Moravec, Vivas-Rodriguez,
Scholz, Vargas-Vazquez, Mendoza-Franco,
Schmitter-Soto, and Gonzalez-Solis, 1995;
Scholz et al., 1995; Salgado-Maldonado et al.,
1997). They have also been reported in atherinids,
goodeids, and other fish families from the
Lerma Santiago River basin in the highland pla-
SALGADO-MALDONADO ET AL.—HELMINTHS OF MEXICAN FISHES 201
teau of central Mexico (Osorio-Sarabia et al.,
1986; Salgado-Maldonado and Osorio-Sarabia,
1987; Leon, 1992; Peresbarbosa et al., 1994).
All these helminth species are widely distributed
in North America, and some are worldwide
(Hoffman, 1967; Yamaguti, 1971; Gibson,
1996).
Some of the helminths found have been introduced
to Mexico with exotic fish or other animals.
The Asian fish tapeworm (B. acheilognathi)
has been disseminated globally in association
with Asian cyprinids (grass and common
carp) introduced to several countries for use in
aquaculture (Salgado-Maldonado et al., 1986).
This tapeworm has broad host specificity and
now occurs in more than 15 freshwater fish species
in Mexico (Garcia and Osorio-Sarabia,
1991). We found B. acheilognathi widely distributed
within the Balsas River basin, parasitizing
8 fish species, mainly poeciliids.
Another example is the heterophyid trematode
C. formosanus that was introduced into Mexico
most probably with the imported thiarid snail
Melanoides tuberculata (Miiller, 1774) serving
as the first intermediate host. This trematode has
rapidly spread to an extensive area, including
central Mexico and both the Atlantic and Pacific
coasts, apparently aided by the previous expansion
of M. tuberculata within Mexico. The
metacercariae of C. formosanus are encysted in
the gills of a wide spectrum of native fishes including
members of Atherinidae, Cichlidae, Cyprinidae,
Eleotridae, Goodeidae, Ictaluridae, and
Poeciliidae (see Scholz and Salgado-Maldonado,
2000). The adults are parasites in piscivorous
birds and mammals. An increasing number of
recent records of C. formosanus in numerous
new hosts and regions, including the Balsas River
drainage, suggests that this helminth is continuing
to expand its distribution (Scholz and
Salgado-Maldonado, 2000).
Too few studies have been undertaken to draw
conclusions about the zoogeographic characteristics
of the helminth communities in the freshwater
fish species of the Balsas River basin.
However, two general statements can be made
about these faunas. The first is that nematode
and trematode species predominate, with only a
few monogeneans and acanthocephalans being
present. Second, all helminths found had previously
been reported from other regions of Mexico;
therefore the taxonomic composition of the
helminth fauna of the fishes of the Balsas River
Copyright © 2011, The Helminthological Society of Washington