#brachaluteres

Southern Pygmy Leatherjacket (Brachaluteres jacksonianus), family Monacanthidae, endemic to the seas off of Southern Australia

Japanese Inflator Filefish (Brachaluteres ulvarum), family Monacathidae, endemic to the seas of Southern Japan

Southern Pygmy leatherjacket - Brachaluteres jacksonianus 

The Southern Pygmy Leatherjacket is a small member of the Monacanthidae family, (Order Tetraodontiformes), belonging to the species Brachaluteres jacksonianus.

The Southern Pygmy Leatherjacket is endemic to Australia. It is up to 9 cm in length and has a very compressed body, which is almost circular. The lower surface is made up of a large ventral flap (called a dewlap) which can be raised and lowered. The abdomen is also expandable by inflating. Like all the leatherjackets, the Southern Pygmy Leatherjacket lacks pelvic fins. Instead, they all have a shaft-like pelvic bone, the end of which is covered with specialized scales.

Their color is highly variable, ranging from a pale yellow-brown to dark green with small spots or ocelli.

Males of this species exhibit a noticeable display. The male fully expands the ventral flap and caudal fin, synchronously quivering the fin and quickly raising and lowering the dorsal spin (vibrating). In the photo can clearly see the inflated throat pouch and bright blue coloration of the display.

References: [1] - [2]

Photo credit: ©John Turnbull