Description

Body design

A medium-sized shrimpgoby, growing to 11 cm in length, grey brown in colour with five vertical bars along the body, the first between the nape and the posterior margin of the opercle and the last on the caudal peduncle just anterior to the caudal fin, which has a separate brown bar near its origin. These are bicoloured, being grey brown with the central portion a contrasting red-brown. The area between these is divided into a dorsal region decorated with coarse black speckles surrounding a pair of contrasting white circular patches; and a ventral portion taken up by a single larger circular white patch with a fine yellow border. The upper margin of this patch is marked by black speckles, forming a letter W with the speckles of the dorsal sector. 

Head design

The face is pale grey with a diagonal reflective blue line below and behind the eye. There are reflective blue spots on the opercle. The nape is brown with darker brown spots. There is a black line running back from the eye and another curving back from the angle of the mandible. These lines are not always visible. 

Fin Design

The first dorsal fin is triangular and transparent with brown accentuation of the spines. The second dorsal fin is translucent with a row of small yellow spots at the edge of the fin membranes. The anal fin is opaque blue-green along the base and translucent distally without an obvious dividing line. The pelvic fin is yellow at the base with radiating broken blue lines and the distal background divided into a blue anterior and red posterior zone. The Pectoral fin is transparent. The Caudal fin is spear shaped, translucent with a brown bar near its base. 

Influence of habitat On darker sand the colour of the pigmented areas is intensified and the head markings more reliable. 

Diagnostic features

The division of the body segment between the bicoloured bars into an upper densely speckled and a lower conspicuously white portion is the significant field character of this species. The markings on the head when present are significant but are not always visible. The line behind the eye is not as pronounced as the similar line seen in A gymnocephala. 

Similar Species

The Longspine shrimpgoby, A macronema is similar to this species but differs in having red spots and extended rays on its first dorsal fin. It lacks the bicoloured body bars and it has a single tear drop black patch under the chin. The anal fin also has a different pattern. 

It is very similar to Amblyeleotris masuii, Masui’s Shrimpgoby which lacks the unusual light and dark body bars (the bars being a uniform colour) and has a red tip along the dorsal fins. It is reported to occur in Indonesia, Philippines and the Ryukyu Islands of Japan. We have not seen specimens of this species for comparison. 

Taxonomy

The species we are seeing differs in several respects from the Type description. The position of the bars on the body does not quite conform to the type description, notably the fourth bar which in the Type specimen is mostly behind the second dorsal and anal fins and in ours is well within the margins of the two. 

There are differences in the fins. Our first dorsal fin is transparent with brown accentuation of the spines Our images do not show the brown network and brown edge of the type description. 

Our second dorsal fin is translucent with a row of small yellow spots at the edge of the fin membranes. Again this does not match the Type which has two yellow lines and a brown edge. 

Our pelvic fin is yellow at the base with radiating broken blue lines and the distal background divided into a blue anterior and red posterior zone The Type is ‘pale brownish’. 

Type description has good colour description and differentiation from similar species, A. fontanesii (!) and A. japonica (black blotches on each side of chin). 

The images in Allan and Eardmann (2012) are different again but conform better to the Type description. Perhaps we should just accept this as a species with variable markings. 

Randall and Earle in 2006 described A neumanni and contrasted it with A stenotaeniata from which it is totally different. Had it been contrasted with A macronema it would have been evident that it was probably the same species. The image in Fishbase of A neumanni should probably be changed to A macronema. 

A. biguttata may turn out to be a junior synonym of A stenotaeniata (Allen and Eardmann 2012). It has been described from Honiara. We have images from Honiara and other parts of the Solomon Islands of a fish that could be either species. We have not been able to make the distinction as we have no images that show the underside of the chin. The vertical line below the eye in A stenotaeniata could easily extend into a chin spot on either side.