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Medientyp:
E-Artikel
Titel:
Ultrastructure of Gnathostomaria lutheri Ax (Gnathostomulida: Scleroperalia).I. An Hypothesis About the Origin of Micropodia in Scleroperalian Sperm
Beteiligte:
Sterrer, Wolfgang;
Salvenmoser, Willi;
Rieger, Reinhard M.
Beschreibung:
<jats:p><jats:bold>Abstract. </jats:bold> Initially described as an aberrant taxon of turbellarian flatworms, the Gnathostomulida were recognized as a distinct phylum by Rupert Riedl already in 1969. Yet these microscopic, non‐segmented marine worms remain organisms of enigmatic phylogenetic affiliation, and although they are often the dominant invertebrate taxon in detritus‐rich, oxygen‐poor sands, our knowledge of their biology is still very scanty. About 90 gnathostomulid species are known to date; they are grouped in two orders, one with two suborders. Sperm structure, often a useful instrument for clarifying evolutionary pathways in metazoan taxa, differs so widely between the orders and suborders that sperm phylogeny within the Gnathostomulida also remains uncertain. We here report on the ultrastructural features of a peculiar type of sperm, the aflagellar “megasperm” of <jats:italic>Gnathostomaria lutheri, </jats:italic> and discuss new and older interpretations of sperm cytology of the taxon.</jats:p>