Reproduction and development in Cirratulidae (Annelida: Polychaeta)

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Abstract

Reproduction and development in 10 genera of Cirratulidae (Annelida: Polychaeta) are reviewed on the basis of the literature and personal observations on living and preserved material. Most species are gonochoristic and spawn freely, but parthenogenesis (Dodecaceria) and hermaphroditism (Aphelochaeta, Caulleriella, Chaetozone, and perhaps Dodecaceria), sometimes with viviparity (Caulleriella, Chaetozone, Cirratulus(?) and Dodecaceria), occur in several genera. Some species of Caulleriella, Cirratulus, Dodecaceria, Protocirrineris, Timarete, and perhaps Chaetozone, reproduce asexually by architomic fragmentation, later developing into sexual individuals with or without epitoky. Asexual regenerates of the first five genera (including types of the bitentaculate Cirratulus gayheadius) are figured, most species for the first time. Epitoky is discussed, some features are figured, and the only known male epitoke of Dodecaceria saxicola is illustrated. Failure to recognize reproductive stages, especially asexual regenerates, has often led to taxonomic confusion. Cirratulid gametes are poorly investigated; most observations are anecdotal comments on presence, color or size of oocytes, less frequently sperm, and are based on light-microscopical studies; sperm ultrastructure has been described for only one species of Cirriformia; cirratulid oocytes have not been studied ultrastructurally. Light microscopical observations show cirratulid sperm to be aquasperm of both the long-headed (ent-aquasperm, e.g. some species of Aphelochaeta) and short-headed (ect-aquasperm, all genera?) types. The karyology of cirratulids has been studied in only three species. Planktonic larvae occur but have not been reported from the plankton; most observations on larval development are based on species with direct development, often with brood care in the tube or burrow of the adult (Aphelochaeta, Dodecaceria), in a jelly mass on the bottom or in the burrow (Cirratulus, Dodecaceria), or in jelly on the body or among tentacles and branchiae of the adult (Cirratulus). Some larval stages of Caulleriella (the hermaphroditic C. parva) are figured for the first time. Sexual dimorphism has been found in Aphelochaeta and the genus of ‘Cirratulus’ branchioculatus. Poecilogony is known for one laboratory culture of Cirriformia. ‘Intraspecific’ differences in life histories of ‘well known’ species probably indicate unjustified synonymization or failure to recognize distinct elements of species complexes. Types of Chaetozone setosa Malmgren, 1867, have been examined; a lectotype is designated herein.

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