Revision of Cryptogonimus Osborn, 1903 and Caecincola Marshall et Gilbert, 1905 (Digenea: Cryptogonimidae), supplemental description of Cryptogonimus chili Osborn, 1903, and description of a new species of Caecincola infecting basses (Centrarchiformes: Centrarchidae) in Tennessee and Alabama rivers.

Abstract

We provide a supplemental description of the type species for Cryptogonimus Osborn, 1903 (Digenea: Cryptogonimidae), Cryptogonimus chili Osborn, 1903, based on newly-collected, heat-killed, formalin-fixed specimens infecting rock bass, Ambloplites rupestris (Rafinesque), and smallmouth bass, Micropterus dolomieu Lacepède (both Centrarchiformes: Centrarchidae), from the Duck River, Tennessee (USA). We emend Cryptogonimus to include features observed in the present specimens of its type species and in the descriptions of its congeners: a broad (wider than long) oral sucker, an intestine that bifurcates in the posterior half of the forebody, a bipartite seminal vesicle, a hermaphroditic duct that is dorsal to the ventral sucker, a preovarian seminal receptacle, and a Laurer's canal that opens dorsally at the level of the anterior testis. We describe Caecincola duttonae sp. n. (Cryptogonimidae) infecting largemouth bass, Micropterus salmoides (Lacepède), from Neely Henry Reservoir (Coosa River, Alabama, USA). The new species differs from its congeners by having a combination of a less elongate body, an intestine that bifurcates at the level of the ventral sucker, caeca that terminate at the level of the testes, diagonal testes in the middle of the hindbody, and a vitellarium predominantly distributed in the hindbody. We emend Caecincola Marshall et Gilbert, 1905 (type species Caecincola parvulus Marshall et Gilbert, 1905) to include features of the new species and recently-described congeners: an elongate body, an intestine that bifurcates in the posterior half of the forebody, caeca that extend posteriad beyond the testes, tandem testes, and a vitellarium that is wholly or primarily in the hindbody. Our 28S and ITS2 phylogenetic analyses recovered Caecincola and Cryptogonimus as sister taxa; Caecincola was recovered as paraphyletic with 28S but monophyletic with ITS2. This is the first phylogenetic study of Cryptogonimidae that includes a nucleotide sequence for a species of the type genus Cryptogonimus. We regard Cryptogonimus diaphanus (Stafford, 1904) Miller, 1941 as a species inquirenda.