Seven late juvenile stages or young males, two late juvenile stages or males fixed in the process of moulting, three stage-1 and seven stage-2 females, and 17 juvenile specimens of Campyloderes cf. vanhoeffeni Zelinka, 1913 from various locations as well as a late juvenile or male and a juvenile specimen of Ryuguderes casarrubiosi Cepeda et al., 2022 were studied by light microscopy. The investigation yielded important insights into the life history of mainly the former species, viz, (1) establishment of clear distinctive characters between late juvenile and female as well as more maturated male life history stages, (2) the principal developmental series of juvenile stages, (3) development of spines via anlagen and modified spines, and (4) dissolution of septa in the primary spinoscalids of the head during moulting.
Meiofauna, Kinorhyncha, Postembryonic development, Deep sea
