A survey of freshwater fishes and their macroparasites in the ... - NINA

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NINA Report 635
Even in our quite restricted data set, we see the generally observed trend that the number of
species decreases with altitude. The rate of decrease is similar on both sides of the divide, but
the intercept (“number of species at sea level”) reflects the richer fauna on the Atlantic side
(Smith & Bermingham 2005). In this case, the main reason for a decreasing number of species
with altitude is probably the steep river gradients. At high altitudes, minimum water temperatures
might also restrict some species. All our investigated sites are in forest, implying that the
supply of organic material of a terrestrial origin (allocthonous material) is quite abundant.
5.2 Parasite diversity
The parasite faunal composition, in general, follows the biogeographical patterns and history of
the hosts. The freshwater fishes of central America are largely neotropical in origin (e.g., Cichlidae,
Characidae, Heptapteridae). The most widely cited scenario involves the colonization of
this area by cichlids, characids and freshwater catfishes from South America once the isthmian
landbridge was established in the Miocene or in the case of some salinity tolerant migrants
(some cichlids) as components of the land-bridge were being assembled (Smith & Bermingham
2005). It is also hypothesized that some families such as Cichlidae and Poeciliidae underwent
significant adaptive radiation in the lower central American region (Smith & Bermingham
2005).
The parasite fauna of cichlids reported in this study resembles closely the fauna reported from
southern Mexican cichlids (Vidal-Martinez et al. 2001; Pérez-Ponce de León & Choudhury
2005). The finding of trematodes such as Wallinia chavarriae, Prosthenhystera obesa and
Paracreptotremtina (likely aguierrepequenoi) in the small bodied characids (Astyanax and Bryconamericus)
connects it to the South American characid parasite fauna. The presence of
nematodes such as Neocucullanus sp. in Brycon guatemalensis and Cucullanellus pimelodellae
in the catfish Rhamdia nicaraguense further reinforces this neotropical/South American
connection, as these parasite taxa also are associated with the South American fauna..
Poeciliidae, Alfaro cultratus, 56
mm, Rio Sapoa (locality 3; 240 m
a.s.l.).
Characidae, Astyanax aeneus,
79 mm, Rio Sapoa (locality 2;
205 m a.s.l.).