English Name: Redtail filefish
Family: MONACANTHIDAE
Local Name: Dhon kothari fathirondu
Order: Tetraodontiformes
Size: Max. 16 cm
Specimen: MRS/0282/88
Distinctive Characters: Dorsal fin with 2 detached spines and 29-34 rays. Anal fin with 26-30 rays. Pectoral fin with 11-13 (usually 12) rays. Snout short. Dorsal profile concave. First dorsal spine origin over centre or front half of eye. A row of large laterally directed barbs along each lateral edge. Shallow groove for receiving first dorsal spine. Caudal peduncle short and broad.
Colour: Orange-brown with irregular fine longitudinal dark brown lines on body. A dark blotch over gill opening. Caudal fin orange with small yellow spots, the outer border with blue and yellow lines.
Habitat and Biology: Usually seen in shallow coral reefs to 20 m depth. A secretive species.
Distribution: Indo-Pacific.
Remarks: Pervagorjanthinosoma is closely related to P. a/ternans and P. aspricaudus. P. alternans differs by having a bright yellow ring around eye. P. aspricaudus has numerous tiny black spots rather than narrow black lines on the sides.