
A history of Brachioptilon hamiltoni
Manta rays have a horrid taxonomic history, with many species or genera proposed based on all sorts of arbitrary minutiae, such as tiny differences in anatomy or geographic range; oftentimes a new species or genus would be named based on a single specimen. One such trait historically thought to be useful for species determination was the coloration of the dorsal side of the ray, known for drastic changes in colors and unique patternings on occasion. Specimens with "white bands" on the shoulders have remained a particularly elusive type, best published on by William Beebe (hence the type later being dubbed "Beebe's Manta" by G.G. Sehm in the journal Cryptozoology). In 2014, it was realized that these white bands were temporary flushes of color, the mantas displayed white shoulders when hungry, aroused, or otherwise just having fun. These markings still vary by species but since there are now only ~3 species (thanks DNA), identification using the white shoulders is a lot more simple today.
Here's a (likely incomplete) history of a very obscure proposed genus/species of manta ray, Brachioptilon hamiltoni, which has a surprisingly long history within cryptozoology, involved since its proposal. Many thanks are owed to u/0todus_megalodon for significant aid in researching this subject!
Brachioptilon hamiltoni was first proposed by Edward Newman in the 7th volume of The Zoologist, published 1849, based on a large specimen speared by Captain Cospatrick Baillie Hamilton off California, the drawing of which seems unpublished. That same volume saw an additional record discussed by George Guyon, based on an individual captured in the Gulf of Mexico. You'll note how both articles are sandwiched between notes on sea serpents, the Stronsa beast, and other cryptids.
The genus also gets some attention in a Swedish book discussing numerous cryptids including the Minhacao, living plesiosaurs, and giant birds. I've not seen this source acknowledged before, and am unsure of its significance to these subjects. A.C. Oudemans further mentions it in his treatise on the sea serpent! Quite an impressive history of indirect association with cryptozoology, hanging alongside key players of the 19th and 20th centuries.
Newman’s description was very brief, making ichthyologists quite uncertain of the standing of B. hamiltoni, with one author even describing Newman’s description as useless. Essentially all sources agreed that Brachioptilon was synonymous with the (now obsolete) genus Manta, but there was disagreement on what species it represented. Some authors used the combination of M. hamiltoni, deemed the “Pacific Manta” or “California sea-devil”. This persisted in some publications well into the late 1960s, and even saw use in museums, with color, again, stated as the clearest demarcation between species. Another now obsolete species, M. pinchoti, was even sunk into M. hamiltoni by Beebe! Others went in the opposite direction - according to Millar (1899) Jordan & Evermann's "Fishes of North and Middle America" (1896) is the first source to synonymize Brachioptilon hamiltoni with Manta birostris (a determination that has held true today).
As I said, Beebe's Manta became a cryptozoological subject through an article by G.G. Sehm. The paper in Cryptozoology is a mixed bag, omitting the very important Beebe article, which includes a bibliography of several examples of white-shouldered mantas known at the time, as well as the important discussion by Notarbartolo-di-Sciara & Hillyer (1989), which seems to be the second real modern recognition of the color as identifying characteristic problem. Several instances from after Beebe's paper, however, are first reported by Sehm and contemporary reportings by Karl Shuker (Mysteries Of Planet Earth, Fortean Times, see also his blog).
This history of white-shoulders is not discussed by the 2014 paper, leaving a huge gap in recording. There's many cool forgotten historical observations of these things, including old artwork and footage located by yours truly. I’ve shared some other miscellany elsewhere. Hope to publish on this all eventually.