(Gastrotricha): new morphological data and description of the spermatozoon

Maria Balsamo (1) , L. Guidi (1) , M. Ferraguti (2) , L. Pierboni (1) , R. M. Kristensen (3)

1 Dipartimento di Scienze dell'Uomo, dell'Ambiente e della Natura
2 Dipartimento di Biologia
3 Zoological Museum [Copenhagen]

The genus (Gastrotricha Chaetonotida) includes two species, and ; its morphological affinity with the genus has been pointed out. Here, new morphological data from light and electron microscopy and the description of the spermatozoon of are reported, with the aim of clarifying the phylogenetic position of the genus. The mouth cavity has a wreath of stout, protrusible processes. The two secondary furcal tubes are inserted ventrally and are covered with elongate scales. All the caudal tubes contain a duo-gland adhesive system. Three kinds of ciliated sensory receptors are described for the first time in . The filiform spermatozoon consists of an acrosome, a nuclear-mitochondrial complex, and a flagellum. The acrosome including two long and different cones, the single, giant mitochondrion surrounding the nuclear base, and the axoneme arising from a deep nuclear ‘fossa' appear as autapomorphic characters. The keeled, solid cuticular body scales and the spermatozoon with a supernumerary membrane are features shared with . The structure of the accessory fibres is a strong spermatological similarity between the families Muselliferidae and Xenotrichulidae. Thus morphological and spermatological characters support the inclusion of and into the family Muselliferidae recently described. The comparative spermatology also suggests that Xenotrichulidae may be the sister group of Muselliferidae.

Mots clés: Gastrotricha; Chaetonotida; Ultrastructure; Spermatozoon

Maria Balsamo, L. Guidi, M. Ferraguti, L. Pierboni, R. M. Kristensen. (Gastrotricha): new morphological data and description of the spermatozoon. Helgoland Marine Research, 2009, 64 (1), pp.27-34. ⟨10.1007/s10152-009-0163-x⟩. ⟨hal-00535198⟩