Morphological Confirmation of Homalometron (Trematoda: Apocreadiidae) Species in Freshwater Fishes in Southeastern Texas, USA, with Description of Two Species

摘要

Recent work using DNA sequence data considered Homalometron armatum (McCallum, 1895) Manter, 1947 (Trematoda: Apocreadiidae) to consist of 3 species. The goal of the present investigation was to test, using new collections, whether these 3 putative species could be recognized and differentiated morphometrically. Newly collected worms from freshwater drum (Aplodinotus grunniens) and redear sunfish (Lepomis microlophus) in Texas, U.S.A., were combined with existing museum collections in multivariate analyses of morphometric characteristics. Principal components analysis on new collections suggested that worms did group by morphometric characteristics relativized by worm length. Discriminant function analyses demonstrated a high degree of fidelity between a priori classification of worms and the ability to discriminate among populations using morphometric data. Based on these results, the 2 as-yet undescribed species of Homalometron are named herein.