Description

Body design

A small shrimpgoby up to 4 cm long, with small dark-edged yellow spots scattered over the body and fins from the cheek to the caudal fin base. The body is pale brown with five broad, brown saddles becoming narrower and darker down the sides. The second and third saddles are slightly broken up dorsally. There is a line of brown blotches mid-laterally between the saddles. 

The face is pale and is covered with brown-edged yellow spots. There is a distinct dark red patch on the operculum. There is a dark band running from the rear corner of the mouth to the eye, and extending over the top of the head. 

Fin design

The first dorsal fin is triangular with a curved posterior edge. There are blue and yellow spots and lines at the base but the fin is primarily transparent. In the female, the fin is otherwise undecorated. In the male the first three rays are markedly extended, the third being the longest.

The second dorsal fin is rectangular, and pale blue with four rows of yellow spots and a yellow margin. The pectoral fin is translucent and the pelvic fin is creamy white. The anal fin is yellow basally followed by stripes of blue, brown, blue, and orange near the margin. The caudal fin is a distinctive swallow-tail shape, with branched, filamentous fifth and ninth caudal fin rays. The background colour is yellow dorsally and orange-brown ventrally with blue lines between the rays.

In areas of dark sand habitat, they may be spectacularly colourful. On the pale grey sand of the Great Barrier Reef lagoon pale grey sand, the colours are more subdued.

Diagnostic features

Most illustrations of this goby show the male displaying, which is quite spectacular. The species is normally a very drab dark brown and is probably overlooked and/or misidentified. This goby is distinguished by the dark-edged yellow spots over the head and body with its five dark saddles. The red colour of the operculum is distinctive.

Similar species

Vanderhorstia macropteryx and V auropunctata, 

Tomiyamichthys latruncularia is found in the same habitat and is superficially similar although it lacks the yellow spots and has a different first dorsal and caudal fin.

Etymology

The specific name is from the Latin papilio (= butterfly), in reference to the elongate, filamentous fifth and ninth branched caudal-fin rays (like the ‘tails’ of the swallowtail butterfly).