Studies on the Trematode Family Azygiidae. I. The Morphology and Life Cycle of Proterometra macrostoma Horsfall

Proterometra epholkos sp. n. (Digenea: Azygiidae) from Terrapin Creek, Alabama, USA: Molecular characterization of life cycle, redescription of Proterometra albacauda, and updated lists of host and geographic locality records for Proterometra spp. in North America

“…Prior to Horsfall [1], wherein she proposed Proterometra, species of Proterometra were assigned to the collective group name Cercaria [3,17,20] (see International Code of Zoological Nomenclature [ICZN] page 70, article 67.14). Subsequent to the establishment of Proterometra, published works assigned the adults and cercariae separately, with the former being assigned to Proterometra and the latter to Cercaria [1,6,15,16,24,33]. To provide taxonomic resolution within Proterometra we discuss conspecificity of species assigned to Cercaria and treat those species as junior subjective synonyms of their conspecific adults assigned to Proterometra.…”

“…6,12). Others have referred to these tail stem protuberances as "papillae" [22] or "wartose structures" [33]. Herein, we refer to Lawrence [85] and call these protuberances on the tail stem 'mamillae'.…”

“…Dickerman [33] studied cercariae from E. livescens (as G. livescens correcta) in the Des Plains River, Illinois, and adults from Pomoxis nigromaculatus (as Pomoxis spiroides), Micropterus salmoides (as Helioperca incisor), and L. gibbosus (as Eupomotis gibbosus). He considered these specimens conspecific with P. macrostoma but, again, no voucher materials reportedly were deposited.…”

“…This makes the assessment of operational taxonomic units based on cercarial morphology alone challenging, especially given the low number of reported diagnostic characteristics. Various workers have treated morphology, behavior, and host-parasite relationships of the cercariae [13,[6][7][8][9][10][11][12]33,[66][67][68][69][70][71][72], development and morphology of the eggs [35,73] and adults [1,6,15,[21][22][23][24][25]28,33,35], and general attributes of the intra-molluscan stages, sporocyst and redia [11,14,74]. Moreover, 8 cercarial strains of P. macrostoma have been morphologically characterized from Lake Erie [13], Kentucky [8,75], Michigan [8], and Ohio [8].…”

“…Since Dickerman [33], experimental infections of Proterometra spp. (8 of 10 species) have indicated that these flukes undergo asexual reproduction in freshwater prosobranch snails, primarily of Elimia but also Pleurocera acuta [1,6], Lithasia obovata [4; see Graff [39] for synonymy], and Campeloma subsolidum [3], that range in rivers and streams draining to the Great Lakes, Gulf of Mexico, and Atlantic Ocean (Table 1).…”