Trematoda (Platyhelminthes) of the Gulf of Mexico

Authors

Robin M. Overstreet, University of Southern Mississippi
Joshua O. Cook, University of Georgia
Richard W. Heard, University of Southern Mississippi

Date of this Version

2009

Citation

Gulf of Mexico Origin, Waters, and Biota, Volume 1: Biodiversity

Edited by Darryl L. Felder and David K. Camp

Chapter 23, pages 419-486

College Station, Texas, United States: Texas A&M Press, 2009

Comments

Copyright 2009, Texas A&M University Press and the authors. Used by permission.

Abstract

First paragraph:

The platyhelminth class Trematoda, consisting of the subclasses Aspidogastrea and Digenea, contains individuals referred to as digeneans, trematodes, or flukes. Aspidogastreans, not digeneans in the strict sense2 number about 80 species in total (Rohde 2005), but adults in the Gulf of Mexico of 4 species have been reported from teleost and chondrichthyan fishes (Hendrix and Overstreet I 977) and one from a turtle (Wharton 1939). Consequently, this chapter deals with trematodes rather than just digeneans, even though all the records but the 5 refer to digeneans. Trematoda is the largest group of platyhelminths, and trematode adults, other than exceptional cases in both Aspidogastrea and Digenea, occur in vertebrates. Rather than being totally restricted to a lumen like members of its sister group Eucestoda (tapeworms), trematode species occur in a variety of sites, exhibiting rather restricted site specificity for each species or higher group. The intriguing situation about trematodes is that they have a molluscan first intermediate host. The larval stage of the aspidogastreans (cotylocidium) does not undergo asexual replication in the mollusk like it does for the digenean counterparts. Digeneans have a series of asexual stages reproducing large numbers of individuals originating as the larva (miracidium) from a single egg that assure transmission and dispersal to a series of one to 3 different, necessary intermediate hosts. With the exception of a few aporocotylids (fish blood flukes) that have larvae developing in polychaetes and maturing in fish, all species in the approximately 17 S families n:quire the molluscan first intermediate host. Of the approximately 18,000 nominal Trematoda. After Overstreet 1973. trematode species worldwide, including well over 5,000 of those from fishes alone (Cribb 2005b), perhaps the largest group of internal metazoan parasites (Cribb et al. 2001), almost all are highly specific for at least the first, second, or final host. On the other hand, at one or more of those 3 stages many digenean species infect several different species of hosts. The number of named or accepted species is low, primarily because of the lack of attention paid to this difficult group of mostly tiny soft-bodied worms. This chapter provides an initial attempt to document records. We do not agree with all, are sure several have been unintentionally omitted, and are sure the lists present a woefully incomplete record because of a paucity of collections and the fact that we have many new records that are not included for lack of time at present.