PHYLOGENY AND A REVISED CLASSIFICATION OF THE MONOGENOIDEA BYCHOWSKY,1937 (PLATYHELMINTHES)

A hypothesis (CI = 57.3%) on the evolutionary relationships of familie s comprising the class Monogenoidea is proposed based on 141 character states in 47 homologous series and employing phylogenetic systematics . Based on the analysis, three subclasses, the Polyonchoinea, Polystom atoinea and Oligonchoinea, are recognised. The analysis supports indep endent origins of the Montchadskyellidae within the Polyonchoinea and of the Neodactylodiscidae and Amphibdellatidae within the order Dactyl ogyridea (Polyonchoinea); the suborder Montchadskyellinea is raised to ordinal status and new suborders Neodactylodiscinea and Amphibdellati nea are proposed to reflect these origins. The Gyrodactylidea (Polyonc hoinea) is supported by three synapomorphies and comprises the Gyrodac tylidae, Anoplodiscidae, Tetraonchoididae and Bothitrematidae. The ana lysis supports recognition of the Polystomatoinea comprising Polystoma tidae and Sphyranuridae. Evolutionary relationships within the Oligonc hoinea indicate independent origins of three ordinal taxa, the Chimaer icolidea (monotypic), Diclybothriidea (including Diclybothriidae and H exabothriidae) and Mazocraeidea (with five suborders). The suborder Ma zocraeinea comprises the Plectanocotylidae, Mazocraeidae and Mazoplect idae, and is characterised by two synapomorphies. The suborder Gastroc otylinea, characterised by presence of accessory sclerites in the hapt oral sucker, is divided into two infraorders, the monotypic Anthocotyl ina infraorder novum and Gastrocotylina. Two superfamilies of the Gast rocotylina are recognised, the Protomicrocotyloidea and Gastrocotyloid ea; the Pseudodiclidophoridae is considered incertae sedis within the Gastrocotylina. The suborder Discocotylinea comprises the Discocotylid ae, Octomacridae and Diplozoidae and is supported by four synapomorphi es. The monotypic Hexostomatinea suborder novum is proposed to reflect an independent origin of the Hexostomatidae within the Mazocraeidea. The terminal suborder Microcotylinea comprises four superfamilies, the Microcotyloidea, Allopyragraphoroidea, Diclidophoroidea and Pyragraph oroidea. The analysis supports incorporation of the Pterinotrematidae in the Pyragraphoroidea and rejection of the monotypic order Pterinotr ematidea. The following taxa are also rejected for reasons of paraphyl y and/or polyphyly: Articulonchoinea, Bothriocotylea, Eucotylea, Monoa xonematidea, Tetraonchidea, Gotocotyloidea, Anchorophoridae and Macrov alvitrematidae. The Sundanonchidae, Iagotrematidae and Microbothriidae were not included in the analysis because of lack of pertinent inform ation regarding character states.