[6] The sister species (the closest relative) is Pleurobranchus varians from the Central Pacific.

[6] Those two species split 3.10 million years ago (the Isthmus of Panama formed 3.1–3.4 Mya).

[6] Both species have color morphs and for their proper determination the knowledge of their locality is needed.

[6] Pleurobranchus areolatus occurs off Mexico, Costa Rica, Venezuela, Brazil, Jamaica, Puerto Rico, St. Thomas, Aruba, St. Maarten/St Martin, Bahamas, Bermuda, Panama,[7] Canary Islands and Madeira.

[1] P. areolatus was also reported from the eastern Pacific, but those records were identified as Pleurobranchus digueti in 2015.

[7] The background color ranges from light brown to deep violet, with varying degrees of opaque white pigment on the tubercles.

[7] In some cases the opaque white pigment is arranged in a symmetrical pattern across the body.

[9] A well marked pedal gland is visible at the posterior end of the foot in some preserved specimens.

[6] The most recent drawing of the reproductive system was published by Goodheart et al. (2015)[6] and by Alvim & Pimenta (2016).

[2] They are laying large, translucent and gelatinous egg masses during spring in Florida.