Phylogeny, coevolution, and revision of the hexabothriidae price, 1942 (Monogenea)

Abstract

Using 92 character states comprising 42 transformation series, a hypothesis on evolutionary relationships of hexabothriid genera was constructed employing phylogenetic systematics. The analysis supports division of the family into subfamily taxa. Three clades, Epicotyle-Neonchocotyle-Callorhynchocotyle, Heteronchocotyle-Paraheteronchocotyle-Rhinobatonchocotyle, and Rajonchocotyle-Squalonchocotyle-Protocotyle, appear cohesive; Hexabothrium, Erpocotyle, and Dasyonchocotyle developed independently from ancestral stock. Tests for coevolution with phylogenetic hypotheses proposed by Compagno (1977, American Zoologist 17: 303-322) for elasmobranchs suggest a relatively high evolutionary independence for hexabothriids. Emended family and generic diagnoses are provided; Hexabothrium dasyatis Yamaguti, 1968, is transferred to Dasyonchocotyle; Squalonchocotyle somniosi (Causey, 1926) is a proposed junior subjective synonym of S. borealis (van Beneden, 1953); the following are considered incertae sedis: Erpocotyle mavori (Linton, 1940); E. pontica Pogoreltseva, 1964; E. septistoma Maillard & Paperna, 1978; Hexabothrium musteli (MacCallum, 1931); H. akaroensis Dillon & Hargis, 1968; Neoerpocotyle platensis Mane-Garzon & Holcman-Spector, 1968; Rajonchocotyle pristiuri Maillard, 1970; and Squalonchocotyle impristi Hargis, 1955. © 1989.