Title

Taxonomy and Systematics of Some Freshwater and Coastal Trematodes from Fishes on the Atlantic Rim

Date of Award

2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Coastal Sciences, Gulf Coast Research Laboratory

First Advisor

Robin M. Overstreet

Advisor Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Xiphidiatan digeneans were investigated using morphology and molecular rDNA gene sequence comparisons. A phylogeny based on 28S rDNA gene fragments from 47 species in 40 genera and 23 families revealed that the Barbulostomum and Apocreadium, previously synonymized under Homalometron were accepted genera. Polylekithum, a notional allocreadiid or opecoelid, belonged in an undetermined family closely related to Encyclometridae. Morphological data for 27 species in 6 families including 11 new species in 5 families was presented. Plagiocirrus n. sp. (Opecoelidae) was described from three topminnow species from the Pascagoula River, Mississippi, USA. Polylekithum n. sp. (undetermined family) was described from the blue catfish, Ictalurus furcatus, from Catahoula Lake, Louisiana, USA. Homalometron n. sp. 1 (Apocreadiidae) was described from Fundulus grandis and several sciaenid fishes from brackish waters in Mississippi and Louisiana. Homalometron n. sp. 2 was described from Aplodinotus grunniens in the Pearl River, Mississippi. Homalometron n. sp. 3 was described from Lepomis microlophus from the Pascagoula River, Mississippi. Cryptogonimus n. sp. (Cryptogonimidae) was described from Pomoxis annularis from Lake Chotard, Mississippi. Crepidostomum n. sp. (Allocreadiidae) was described from Hiodon tergisus in the Pearl River, Mississippi. Creptotrema n. sp. 1 (Allocreadiidae) was described from Ancistrus brevifilis and Auchenipterus nuchalis from the Paraguay River, Paraguay. Creptotrema n. sp. 2 was described from Tetragonopterus argenteus from San Pablo, Ecuador. Maicuru n. sp. 1 (Allocreadiidae) was described from Bryconops c.f. caudomaculatus from Rio Itaya, Department of Loreto, Peru. And, Maicuru n. sp. 2 was described from Stethaprion cf. erythrops from Rio Itaya, Department of Loreto, Peru. Morphological cladistic analysis of apocreadiid genera revealed that Crassicutis represents an unnatural group, thus, a new genus will be proposed for Crassicutis marina, C. gerridis, C. caranxi, C. karawarensis, and C. imitiazi. Morphological cladistic analysis of allocreadiid genera revealed that the "papillose" allocreadiids probably represent a natural group. Caudouterina is closely related to Polylekithum and is not an allocreadiid. A summary list of known freshwater fish digeneans was provided and the zoogeography of certain modern taxa were discussed in terms of geological events.