A New Species of Allacanthochasmus (Trematoda: Cryptogonimidae) from White Bass, Morone chrysops (Moronidae), from Lake Livingston, Texas, USA

摘要

Allacanthochasmus texanus n. sp. is described from white bass, Morone chrysops, collected from the Trinity River system in southeastern Texas, U.S.A. Specimens of the new species can be distinguished from Allacanthochasmus varius Van Cleave, 1922 by the former's elongate body shape, prominent prepharynx, and tandem testes. The new species is most similar to Allacanthochasmus artus Mueller and Van Cleave, 1932, with which it shares a common body shape, structure of the gonotyl, and distribution and arrangement of most internal structures; the new species differs in having vitelline follicles confined more posteriorly, a gonotyl with more root-like processes, and a smaller number of circumoral spines on the oral sucker. The shape of the circumoral spines in A. texanus n. sp. is highly variable, and the type series includes specimens with spines similar to what described for both A. artus and A. varius. Allacanthochasmus texanus is the third species in the genus from North America, and at this time, all 3 species that are considered valid members of this genus have been described from white bass.