[3] C. castelli was discovered from rotting Micropholis cayennensis fruit in the Nouragues Nature Reserve of tropical French Guiana in 2008.

[5] The spicules of C. castelli males possess a short, stout, evenly curved, complex morphology, similar to other Caenorhabditis species within the Angaria and Drosophila groups.

[2] Like most species of Caenorhabditis, C. castelli demonstrates a gonochoristic, or male-female, mode of reproduction, as opposed to C. elegans and C. briggsae which demonstrate an androdioecious mode of reproduction, such that populations primarily include self-fertile hermaphrodites with more rare males.

[2] C. castelli males contain larger sperm cells (28.81 μm2) on average compared to hermaphroditic Caenorhabditis species like C. elegans (19.55 μm2), C. briggsae (18.65 μm2) and C. tropicalis (19.81 μm2).

[5] In the lab, C. castelli can hybridize with C. angaria to produce sterile females and slow growing males.