between these and the Asian genus Spilornis. The syrinx morphology is distinctly like those of accipiter hawks but shows similarities to features found in Nisaetus. Two subspecies are known: the nominate subspecies Dryotriorchis spectabilis spectabilis and D. s. batesi. D. s. batesi was originally described as a separate species, Dryotriorchis batesi, by Richard Bowdler Sharpe in 1904 due to its unspotted breast. Sharpe named the subspecies in honor of G. L. Bates, who shipped him specimens from Cameroon. This species is also known as the West African Serpent eagle and the African Serpent-eagle. Despite Shelley's reclassification, the species was later merged into the genus Circaetus in 2005, along with other taxa popularly known as "serpent eagles". However, a 2018 study recovered this classification as being paraphyletic with respect to Terathopius, and for this reason, reclassified it back into Dryotriorchis. This was followed by the International Ornithological Congress in 2022. The Congo serpent eagle is superficially similar in plumage and size to Cassin's hawk-eagle, which has an overlapping range with the serpent eagle. It has been suggested that the Congo serpent eagle evolved to mimic the Cassin's hawk-eagle, which could give the serpent eagle several advantages, possibly including the ability to trick its reptilian prey into not fleeing, lowering its own predation, and/or minimizing mobbing by birds through its resemblance to a predator of birds. D. s. spectabilis more closely resembles the immature Cassin's hawk-eagle, while D. s. batesi resembles the adult. This is one of very few suspected examples of avian mimicry. Description This hawk is a medium-sized, slender species with short, rounded wings and a long, rounded tail. It is long, with the tail contributing . The wingspan is across. The adult of the nominate subspecies, Dryotriorchis spectabilis spectabilis, has a blackish-brown crown and upper neck while the sides of the neck and a broad collar are a dark rufous-brown. The feathers on the top of the head are slightly pointed, giving this species a hint of a crest. The remaining upperparts are a dark chocolate brown. The cheeks are light brown while the throat is buffy white with streaks. The eyes are large and dark brown or grey in females and yellow in males while the beak is short but deep. It also has a black median streak. The bird's underparts are white with variable amounts of rufous wash and a number of large, round blackish spots. The