Proctocaecum coronarium and Proctocaecum diploporum (Digenea: Cryptogonimidae): Morphologically- and phylogenetically-distinct but closely related and sympatric crocodilian trematodes with identical life cycles
- 1Southeastern Cooperative Fish Parasite and Disease Laboratory and Southeastern Cooperative Fish Genetics Laboratory, School of Fisheries, Aquaculture, and Aquatic Sciences, College of Agriculture, Auburn University, Auburn, AL, USA
- 2Department of Zoology, School for Environmental Sciences and Development, North-West University, Private Bag X6001, Potchefstroom, South Africa
Abstract
During a parasitological survey of the cockscomb hydrobe, Littoridinops monroensis (Gastropoda: Cochliopidae), sympatric saltmarsh fishes and the American alligator, Alligator mississippiensis (Alligatoridae) within a saltmarsh pond in the Bon Secour Bay (Mobile Bay, Alabama, north-central Gulf of America) and other localities, we collected specimens of Proctocaecum diploporum (Stunkard, 1931) Baugh, 1957 and Proctocaecum coronarium (Cobbold, 1861) Brooks, 1980 (Cryptogonimidae). Fish scales were infected with 2 metacercarial cyst size classes, a small (<200 μm) and a large (>240 μm), suggesting the presence of distinct but closely related sympatric cryptogonimids. Morphological and nucleotide evidence demonstrated that P. diploporum (small cyst) and P. coronarium (large cyst), previously regarded as taxonomic synonyms, share the same first intermediate host (cockscomb hydrobe), are encysted within the scales of the same fish host species, and mature in the intestine of the same definitive host. The taxonomy of these trematodes and that of another similar American alligator trematode, Caimanicola pavida (Brooks and Overstreet, 1977) Brooks, 1980, needed reconsideration. Herein, we describe the first complete and naturally occurring life cycle of a reptile-infecting cryptogonimid, provide the first nucleotide data for a species of Proctocaecum, taxonomically reassess both P. diploporum and P. coronarium, and designate a neotype for P. coronarium. We consider C. pavida a junior subjective synonym of P. coronarium. Phylogenetically related and sympatric trematodes that use the same invertebrate and vertebrate hosts such as these Proctocaecum spp. could be a good model to further explore the mechanisms of speciation and host specificity among trematodes with complex life cycles.
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BibTeX
@article{cajiaomora2026proctocaecum,
title = {{Proctocaecum coronarium and Proctocaecum diploporum (Digenea: Cryptogonimidae): Morphologically- and phylogenetically-distinct but closely related and sympatric crocodilian trematodes with identical life cycles}},
author = {Kamila Cajiao-Mora and Stephen S. Curran and John H. Brule and Daniel Gordillo-González and Haley R. Dutton and Micah B. Warren and Stephen A. Bullard},
journal = {Parasitology},
year = {2026},
month = jun,
doi = {10.1017/s0031182026102340},
url = {https://doi.org/10.1017/s0031182026102340},
note = {CC BY-SA 4.0},
}
RIS
TY - JOUR
TI - Proctocaecum coronarium and Proctocaecum diploporum (Digenea: Cryptogonimidae): Morphologically- and phylogenetically-distinct but closely related and sympatric crocodilian trematodes with identical life cycles
AU - Kamila Cajiao-Mora
AU - Stephen S. Curran
AU - John H. Brule
AU - Daniel Gordillo-González
AU - Haley R. Dutton
AU - Micah B. Warren
AU - Stephen A. Bullard
PY - 2026
DA - 2026/06/19
JO - Parasitology
DO - 10.1017/s0031182026102340
UR - https://doi.org/10.1017/s0031182026102340
AB - During a parasitological survey of the cockscomb hydrobe, Littoridinops monroensis (Gastropoda: Cochliopidae), sympatric saltmarsh fishes and the American alligator, Alligator mississippiensis (Alligatoridae) within a saltmarsh pond in the Bon Secour Bay (Mobile Bay, Alabama, north-central Gulf of America) and other localities, we collected specimens of Proctocaecum diploporum (Stunkard, 1931) Baugh, 1957 and Proctocaecum coronarium (Cobbold, 1861) Brooks, 1980 (Cryptogonimidae). Fish scales were infected with 2 metacercarial cyst size classes, a small (<200 μm) and a large (>240 μm), suggesting the presence of distinct but closely related sympatric cryptogonimids. Morphological and nucleotide evidence demonstrated that P. diploporum (small cyst) and P. coronarium (large cyst), previously regarded as taxonomic synonyms, share the same first intermediate host (cockscomb hydrobe), are encysted within the scales of the same fish host species, and mature in the intestine of the same definitive host. The taxonomy of these trematodes and that of another similar American alligator trematode, Caimanicola pavida (Brooks and Overstreet, 1977) Brooks, 1980, needed reconsideration. Herein, we describe the first complete and naturally occurring life cycle of a reptile-infecting cryptogonimid, provide the first nucleotide data for a species of Proctocaecum, taxonomically reassess both P. diploporum and P. coronarium, and designate a neotype for P. coronarium. We consider C. pavida a junior subjective synonym of P. coronarium. Phylogenetically related and sympatric trematodes that use the same invertebrate and vertebrate hosts such as these Proctocaecum spp. could be a good model to further explore the mechanisms of speciation and host specificity among trematodes with complex life cycles.
SN - 0031-1820
SN - 1469-8161
ER -