This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

No abstract

Clinostomum spp. (Digenea: Clinostomidae) are a group of trematodes commonly found in the buccal cavity and oesophagus of a variety of piscivorous birds. The metacercariae, colloquially known as "yellow grubs," have been reported from a diverse group of freshwater fishes worldwide. In the catfish farming region of the southeastern USA, piscivorous birds present a continuous challenge for aquaculturists in the form of fish depredation and the introduction of trematodes into these static, earthen pond systems. Clinostomum spp. are commonly encountered in farm-raised catfish. While generally considered pests of minimal importance, heavy infections can result in unmarketable fillets. Of the piscivorous birds that frequent catfish aquaculture operations in the southeastern US, the double-crested cormorant (Phalacrocorax auritus Lesson) is one of the most damaging, although reports of Clinostomum spp. from P. auritus are limited. In this study, adult trematodes morphologically consistent with Clinostomum sp. were found in the trachea of a double-crested cormorant captured in Lowndes Co., Mississippi, USA. These specimens differed from other recognised Clinostomum spp. in several key morphological characters. Moreover, sequence data of mitochondrial cytochrome c oxidase subunit 1 gene (cox1), nicotinamide adenine dinucleotide dehydrogenase subunit 1 gene (nad1) and ribosomal internal transcribed spacer (ITS) regions did not match any known Clinostomum sp. for which sequence data are available. While genetically similar to C. marginatum and C. album Rosser, Alberson, Woodyard, Cunningham, Pote & Griffin, 2017 reported from the great egret Ardea alba L. in Mississippi, these adult clinostomids were larger in size and limited to the trachea, whereas both C. marginatum Rudolphi, 1819 and C. album are found in the oral cavity and esophagus. Given these distinct morphological and molecular characters we propose a new member of the genus, known hereafter as Clinostomum poteae n. sp. Additionally, larval stages in the life-cycle of C. album are morphologically and molecularly identified for the first time from ramshorn snails Planorbella trivolvis Say and fathead minnows Pimephales promelas Rafinesque.

The digenetic trematode Bolbophorus damnificus is a significant hindrance to the production of farm‐raised catfish in the southeastern USA. Severe infections with Bolbophorus damnificus can result in death, but the real damage lies in mild to moderate infections, which can go unnoticed by producers. Research has shown even mild infections can inhibit production to the point of operating at a net loss. The ramshorn snail Planorbella trivolvis is the first intermediate host for Bolbophorus damnificus and is prevalent in most commercial catfish ponds in the Southeast. Management practices aimed at controlling Bolbophorus damnificus infections primarily focus on reducing snail populations in ponds. Other aquatic snail species are also commonly associated with commercial catfish ponds, although little is known about their contributions to trematode infections in catfish. In the summer of 2014, 804 snails Biomphalaria havanensis (synonym: Biomphalaria obstructa) were collected from a single commercial catfish pond and screened for trematode infections. Seven of these snails (0.81%) were actively releasing cercariae identified molecularly as Bolbophorus damnificus. These cercariae were subsequently used in infectivity trials with Channel Catfish Ictalurus punctatus fingerlings (5–8 cm). Seven days postchallenge, fish were examined histologically for the presence of metacercariae, which were present in 13 of 15 (86.67%) surviving fish. This is the first report of naturally occurring infections of Bolbophorus damnificus in another snail species.