Comparative Parasitology 68(2) 2001 - Peru State College

JALISCO
SALGADO-MALDONADO ET AL.—HELMINTHS OF MEXICAN FISHES 205
Chap '
LAKE'CHAPALA
Figure 1. The Lerma-Santiago River drainage basin of west-central Mexico, showing the fish collection
sites. Locality codes as in Table 1.
review of the literature dealing with freshwater fish helminth
parasites in the entire Lerma-Santiago river basin
was made. In addition, a total of 1,177 fish of 18 species
(Table 1), from 11 localities in the Lerma-Santiago river
basin (Table 2, Fig. 1) was examined for the presence of
helminths from January to October 1997 and from January
to March 1998.
At each site, fish were captured using electrofishing or
gill nets. The numbers of fish examined at each locality
and collection data are given in the parasite-host list (Table
3). After capture, the fish were taken live to the laboratory
and examined within 48 hr using standard procedures.
Briefly, all the external surfaces, viscera, and
musculature of each fish host were examined under a
stereomicroscope, and all the helminths encountered in
each fish were counted. Digeneans (adults and larvae),
cestodes, and nematodes were fixed in hot 4% neutral
formalin. Acanthocephalans were placed in distilled water,
refrigerated overnight (6—12 hr) to evert the proboscis,
and then fixed in hot 10% formalin. Digeneans, cestodes,
and acanthocephalans were stained with Mayer's paracarmine
or Ehrlich's hematoxylin, dehydrated using a
graded alcohol series, cleared in methyl salicylate, and
whole mounted. Nematodes were cleared with glycerine
for light microscopy and stored in 70% ethanol. Voucher
specimens of all taxa have been deposited in the National
Helminth Collection (Coleccion Nacional de Helmintos
[CNHE]), Institute of Biology, National Autonomous
University of Mexico (UNAM), Mexico City. Infection
parameters utilized are those proposed by Margolis et al.
(1982), that is, prevalence (% infected) and mean intensity
of infection (number of parasites per examined fish).
Voucher specimens of the following species, found in
fish from the Lerma-Santiago river basin and deposited
in the CNHE, were examined: Posthodiplostomum minimum
(MacCallum, 1921) (nos. 001253, 001476,
001748); Bothriocephalus acheilognathi Yamaguti, 1934
(no. 000434); Proteocephalus pusillus Ward, 1910 (nos.
000383-000386); Proteocephalus sp. (no. 000425); Ligula
intestinalis (Linnaeus, 1758) [nos. 448(F) and
449(F)], and Contracaeciim sp. [nos. 002508(F) and
002253(F)].
Results
A host-parasite checklist is presented herein
as Table 3. In this study, 43 helminth species are
reported from 33 species of freshwater fishes of
the Lerma-Santiago river basin, west-central
Mexico. Six (14%) of the 43 species are endemic
to the basin: A. mexicanum, M. bravoae, O.
mexicanum, R. lichtenfelsi, Spinitectus sp., and
B. nayaritensis. Fourteen are allogenic species
that mature in, and are transported by, birds: C.
Copyright © 2011, The Helminthological Society of Washington