Figure 1. A female of the type species, Nanaloricus mysticus, from Roscoff, France. The animal is seen from the dorsal view. Abbreviations: an, anus; bu, buccal tube; cv, clavoscalid; du, glandular duct; dv, dorsoventral muscle; fl, flosculum; fu, oral furca; gl, epidermal gland; gu, midgut; lg, lorical spike gland; mo, mouth cone; mt, mouth tube; nu, nucleus; oo, oocyte; os₂, secondary oral ridge; pr₁–pr₂, protonephridia; sr₂–sr₉, scalid rings, ts₁ and ts₂, trichoscalids. (Modified from Kristensen 1991a, drawn by Beth Beyerholm.)

Figure 2. Life cycle of Nanaloricus mysticus, all animals seen from the ventral view. A, female; B, male; C, spermatozoon; D, egg; E, first larval instar; F, last larval instar; G, metamorphosis of Higgins larva to postlarva; H, postlarva. (Modified from Kristensen 1991b, drawn by Beth Beyerholm.)

Figure 3. A male of Pliciloricus enigmaticus from off the coast of North Carolina, USA; the animal seen from the dorsal view. Abbreviations: an, anus; cm, circular muscle; cv, clavoscalid; fl, flosculum; ri, the double organ from the second-ring head appendages. sr₂, leg-shaped spinoscalid of second ring; sv, seminal vesicle; te, testis; ts₁ and ts₂, trichoscalids. (Original drawing by Birgitta Rubaek.)

Figure 4. Life cycles of Rugiloricus, all animals seen from the ventral view. A, The free-laid egg; B, embryo inside the egg; C, first instar larva; D, last instar larva with ovary (neoteny); E, old larval exuvium with eggs and embryos in different stages; F, neotenous larva; G, postlarva; H1, female; H2, male. In R. carolinensis the larva can develop direct to adult (D–H). In R. cauliculus the postlarva is always involved in the life cycle. Neoteny can be present in both species. (Original drawings by Stine Elle.)