Macrognathus pentophthalmos

Macrognathus pentophthalmos, the Sri Lanka five-eyed spiny eel, is a small species of spiny eel that is endemic to freshwater habitats in Sri Lanka. Described as a common species as recently as 1980, for unknown reasons its population rapidly declined in the following years and there are no recent confirmed records.[2] In 2012, it was listed as "Critically Endangered, possibly Extinct" in the Sri Lankan National Red List.[3]

Macrognathus pentophthalmos
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Synbranchiformes
Family:	Mastacembelidae
Genus:	Macrognathus
Species:	M. pentophthalmos
Binomial name
Macrognathus pentophthalmos (Gronow, 1854)
Synonyms[1]
Mastacembelus pentophthalmos Gronow, 1854

It is up to 19.5 cm (7.7 in) in standard length.[4] Compared to Mastacembelus armatus, the only other spiny eel in Sri Lanka, M. pentophthalmos has a striped/plain (not mottled) pattern, and clearly separated dorsal, caudal and anal fins.[2] The English name of M. pentophthalmos refers to the series of dark spots on its dorsal fin.[2]

Described as a new species in 1854, it was then considered a synonym of the widespread M. aral. In 2008 it was shown that this was mistaken and M. pentophthalmos was reinstated as a valid species (the true M. aral is not found in Sri Lanka).[2]