Description

Body design

A medium-sized goby, 10 cm in length, uniformly brown with six yellow-green saddles on the dorsum. The anterior saddle is formed by lines running back from the pale eyebrows to cross the midline in a way that makes the shape of a letter W. The last one is restricted to a pale patch above the caudal peduncle.

The remaining four saddles have finer bars between them and together this makes eight narrow yellow-green bars along the side of the body. All these bars are interrupted by a dark brown mid-lateral stripe running from the eye to the base of the caudal peduncle.

Head design

The head markings are divided by the dark mid-lateral stripe. Below this the head is either brown with distinctive orange spots as far as the gill cleft; or pale yellow, in which case the spots are less conspicuous. The transition from one pattern to the other occurs in a matter of minutes in a single individual. There are three yellow spots on the upper lip. Nostril tubular.

Fin design

The first dorsal fin is triangular with the second to fourth rays extended, the third or fourth usually being the longest. It is translucent pale yellow with, at its base a brown patch opposite each of the dark bands of the body It has a blue leading edge outlined anteriorly in black. There is additional blue streaking on the fin rays of the trailing edge. The second dorsal fin is translucent with a combination of brown spots. brown accentuation of the rays, and an iridescent blue edge. Three rows of fine yellow lines are sometimes evident on the distal part of the fin just below the blue iridescent margin. The pelvic fin is pale grey with red dots. The anal fin is pale grey with brown accentuation of the fin rays, The pectoral fins are transparent and arise from a finely speckled pale patch The caudal fin is pointed, grey with blue iridescent highlighting of the rays. The intervening membranes have a reddish tinge. At the base of the fin, there is a short extension of the mid-lateral stripe.

In the northern Great Barrier Reef, Myersina nigrivirgata has the pattern described but more subtle colouration.

Diagnostic features

The thing that catches the eye is the longitudinal dark line. In the bright-coloured form, the fish is distinctive with its brown body, yellow-green bars and bright blue tail. The yellow pelvic fin is conspicuous. These features are present but more subdued in the more usual sombre form.

Variant form

The images have been chosen to highlight the range of variation.

We have found very brightly marked individuals off Frazer Island in Hervey Bay. The fins are a striking feature of the fish, particularly the bright blue caudal and bright yellow pelvic fins. The vivid blue of the caudal fin is the result of diffraction and in some lights can change to rainbow hues at the red end of the spectrum. The pelvic fin is conspicuously yellow with orange spots and is prominently extended in display or threat. The anal fin is more yellow.

Similar species

The Peacock Shrimpgoby, Cryptocentrus pavoninoides, is similar but has 3 to 4 vertically elongated spots on the first dorsal fin. The pelvic fin is dark.

Also found in Australia is Myersina macrostoma Herre 1934 from SE Anjo Peninsula WA to Gunn Point and Tiwi Islands NT. It is a very different fish.

Taxonomy 

We thought the striking form we found at Frazer Island was a new species, but now feel that it is more likely to be a local variant.

Type Description 

In the type description, the pelvic and anal fins are said to be transparent. Our observation is that the anal fin is solid pale grey with brown accentuation of the fin rays, and the pelvic fin varies from pale yellow with imperceptible markings to bright yellow with orange spots.