Difficulty in species delineation within the Nymphonidae stems from variability of morphology and few physical traits useful to taxonomic analyses (Hedgpeth.
Genetic differentiation in the circum-Antarctic sea spider Nymphon australe (Pycnogonida; Nymphonidae).
Antarctic and Subantarctic Pycnogonida: Nymphonidae. Colossendeidae.
A study of the walking behavior of Phoxichilidium femoratum (Rathke, 1799): family Phoxichilidae and Nymphon brevirostre Hodge: family Nymphonidae was begun at the Nikolai Pertsov White Sea Biological Station (WSBS) operated by Lomonosov Moscow State University during the summer of 2013.
The occurrence of similar walking patterns in four families, Colossendeidae, Pallenopsidae, Phoxichilidae, and Nymphonidae would indicate that this may be the normal walking pattern for octopodous pycnogonids.