Description

Body design

This is a medium-sized goby measuring about 5 cm. The body is silvery with a mid-lateral variegated brown stripe, continuous anteriorly but becoming broken up posteriorly Either side of this is a reflective blue stripe. The body below this is plain white and above this is speckled with brown spots that tend to coalesce into up to six dorsal saddles.

The front half of the body is paler than the remainder.

Head design

The head is brown dorsally with reflective blue and orange scribbled spots on the face. There is a dark red-brown spot on the upper part of the gill cleft. There is an iridescent blue stripe dorsally from the snout to the origin of the first dorsal fin. 

Fin design

The first dorsal fin is the shape of a high triangle. It is translucent with 1 to 2 broad orange stripes basally and faint orange spots/wavy bands covering the rest of the fin and a diffuse orange-brown eye-sized blotch at the base between the second and fifth spines (from underwater photographs in Type description: our images do not show these details ). The second dorsal fin is translucent pale brown with an iridescent blue margin and scattered blue spots. The caudal fin is long and pointed, translucent with continuous blue streaks on the lower half and broken blue dashes on the upper. The anal fin is translucent with a blue edge and a faint brown submarginal stripe The pectoral fins are transparent and arise from a patch of iridescent orange and blue markings. The pelvic fins are solidly coloured, yellow-green basally and blue-grey distally.

The above description applies to the male and to a lesser extent the female, which is more subtly marked. The major points of difference are that the female is noticeably lighter coloured on the body anteriorly and has a conspicuous black bar arising from a black circular patch near the base of the first dorsal fin.

Diagnostic features

This goby is distinguished by the reflective orange and blue scribbled markings on the face, the dorsal blue stripe from the snout to the first dorsal fin and the dorsal fin pattern of the female.

Similar species

V dorsomacula are similar, the colour patterns are the most reliable way of distinguishing these species.

V dorsomacula lacks the characteristic blue edge brownish orange stripes on the side. Instead, it has numerous small yellow-orange spots. The cheeks and operculum are also profusely covered with similar spots rather than the less numerous larger spots bands and bars of V nobilis. Further differences include the lack of a dark sub-marginal band on the anal fin, and black or orange spots on the pelvic fins in V dorsomacula. The first dorsal fin of V nobilis is roughly triangular (with a rounded apex in adult males) compared to the squarish shape of V dorsomacula (Allen and Randall 2006).

Vanderhorstia belloides is also similar in general body colour, the dorsal blue stripe and dark patch on the gill cover. It differs in having darkly outlined yellow spots on the face and two confluent black spots on the trailing edge of the first dorsal fin. It is easily confused with V. dorsomacula but is distinguished by five dark-edged yellow patches on the body below the first dorsal fin.

We have only encountered this species once and had problems with our camera. These photos are very poor quality and do not show the true colours of these fish.