Leptonemella species (Desmodoridae, Stilbonematinae), benthic marine nematodes with ectosymbiotic bacteria, from littoral sand of the North Sea island of Sylt: taxonomy and ecological aspects

• Published in: Helgoland marine research 2003-06, Vol.57 (2), p.118-131
• Main Authors: Riemann, Franz, Thiermann, Frank, Bock, Lars
• Format: Article
• Language: English
• Subjects: Bacteria; burrows; Desmodoridae; fauna; females; Leptonemella; Leptonemella aphanothecae; Leptonemella gorgo; Leptonemella vicina; littoral zone; males; Marine; microhabitats; Nematoda; Nematodes; new species; oxygen; Polychaeta; population density; sand; Stilbonematinae; sulfides; temporal variation
• ISSN: 1438-387X; 1438-3888
• DOI: 10.1007/s10152-003-0149-z

Leptonemella species represent a dominant element of the nematode fauna in sulfidic, deep sediment layers on the sandy shore of Sylt. Based on collections sampled here in 1991–1999, a taxonomic treatise is presented on the three co-existing species, Leptonemella aphanothecae Gerlach, 1950, the closely related L. vicina sp. nov., and L. gorgo Gerlach, 1950. The high incidence of pseudohermaphrodites in the material, mostly functional females with a male copulatory apparatus, is remarkable. The highest population densities of Leptonemella spp. (up to 73 individuals/10 ml sand) were found near polychaete burrows. Because of the great spatial and temporal variations in the oxygen/sulfide regime of these microhabitats, and because of the strong adhesive capabilities of Leptonemella spp., which can anchor themselves firmly to sand grains using caudal glands, we propose that a hemisessile life strategy is employed by these nematodes to fulfill the metabolic needs of their sulfide-oxidizing ectosymbionts.