Comparative Parasitology 67(1) 2000 - Peru State College

Comp. Parasitol.
67(1), 2000 pp. 92-106
Digenean Fauna of Amphibians from Central Mexico: Nearctic and
Neotropical Influences
G. PEREZ-PONCE DE LEON,' V. LEON-REGAGNON, L. GARCIA-PRIETO, U. RAZO-MENDIVIL,
AND A. SANCHEZ-ALVAREZ
Laboratorio de Helmintologia, Institute de Biologia, Universidad Nacional Autonoma de Mexico, A.P. 70-153,
C.P. 04510, Mexico D.F., Mexico (e-mail: ppdleon@servidor.unam.mx: vleon@mail.ibiologia.unam.mx)
ABSTRACT: Specimens from 20 amphibian species from central Mexico were examined for helminths. We found
21 digenean species; 4 of them are recorded for the first time in Mexico. Twenty-two new host and 21 new
locality reports are added. Previous reports of these helminth species are summarized, and biogeographical
aspects of hosts and parasites are discussed.
KEY WORDS: Digenea, taxonomy, amphibians, Mexico, biogeography.
Mexico possesses one of the highest amphibian
species richnesses in the world, with 285
species recorded so far, and an unusual level of
endemism (60.7%) (Flores-Villela, 1993, 1998).
In spite of this richness and the importance of
this group of vertebrates in ecosystems, only
10% of the species in Mexico have been studied
for helminth parasites.
We recently conducted a study of helminth
parasites of amphibians in selected aquatic ecosystems
in Mexico. We surveyed helminths of
frogs, toads, and salamanders from several lakes
of the Mexican plateau (Mesa Central), a tropical
rain forest (Los Tuxtlas, Veracruz State), and
a tropical dry deciduous and semideciduous forest
(Chamela, Jalisco State). In this paper, we
present a list of the digenetic trematodes of 20
species of amphibians that we analyzed during
the last 3 yr. We also provide information about
previous records of each helminth species in
Mexico and discuss biogeographical aspects of
parasites and hosts.
Materials and Methods
Between July 1996 and May 1998, we examined
647 specimens of amphibians belonging to 20 species
and 8 genera (Table 1). We sampled in 12 localities: 8
from the Mesa Central, 1 from the Pacific coast, and
3 from the coast of the Gulf of Mexico (Map 1). However,
digeneans were found only in frogs and salamanders
of the following localities: Cienaga de Lerma, Estado
de Mexico (19°17'N, 99°30'W); Lago de Chapala,
Jalisco (20°17'N, 103°11'W); Lago de Cuitzeo, Michoacan
(19°53'N, 100°50'W); Lago de Patzcuaro, Michoacan
(19°30'N, 101°36'W); Lago de Zacapu, Michoacan
(19°49'N, 101°47'W); Manantiales de Cointzio,
Michoacan (19°35'N, 101°14'W); Los Tuxtlas,
Corresponding author.
Copyright © 2011, The Helminthological Society of Washington
92
Veracruz (Laguna El Zacatal, Laguna Escondida, and
Los Tuxtlas Field Station; 20°37'N, 98°12'W); Estero
Chamela, Jalisco (19°30'N, 105°6'W).
Hosts were collected by hand or with seine nets and
were kept alive before parasitological analysis, which
was carried out within 24 hr after capture. Hosts were
killed with an overdose of anesthetic (sodium pentobarbitol)
and examined by standard procedures.
Digeneans were relaxed with hot tap water, fixed in
Bouin's fluid for 8 hr under coverglass pressure, and
then placed in vials containing 70% alcohol; later, they
were stained with Mayer's paracarmin, Delafield's hematoxylin,
or Gomori's trichrome and mounted in permanent
slides with Canada balsam. Drawings were
made with the aid of a drawing tube. Voucher specimens
of collected worms were deposited at the Coleccion
Nacional de Helmintos (CNHE), Biology Institute,
Mexico City.
Hosts were fixed following standard procedures
(Simmons, 1985) and deposited at the Coleccion Nacional
de Anfibios y Reptiles (CNAR), Biology Institute,
Universidad Nacional Autonoma de Mexico
(UNAM), and in the Coleccion Herpetologica del Museo
de Zoologfa (Faculty of Sciences, UNAM).
Results
We identified 21 digenean species (Figs. 1-
20) of 11 genera and 10 families collected in 10
of the 20 species of frogs and salamanders analyzed
(Table 2). Four of these represent new
records in Mexico, Catadiscus rodriguezi, Glypthelmins
parva, Glypthelmins sp., and Fibricola
sp. metacercariae. We also add 22 new host records
and 21 new locality records. The frog
Rana brownorurn, the salamanders Ambystoma
dumerilii, Ambystoma mexicanum, and Ambystoma
tigrinum, the toads Bufo marinus and Bufo
valliceps, the hylids Hyla arenicolor, Hyla exirnia,
and Pachymedusa dachnicolor, and the leptodactylid
Eleutherodactylus rhodopis were free
from digenean infections.