Redmargin Shrimpgoby
Amblyeleotris rubrimarginata
Redmargined Shrimpgoby
Amblyeleotris rubrimarginata
Mohlmann and Randall, 2002
Description
Body design
This is a medium-sized goby, around 11 cm in length. It is light brown, paler ventrally than dorsally, with 6 pale brown bands.
The body is marked with six red-to-yellow brown bands which are narrower dorsally. Between these is a pattern of fine black speckles ending in a short vertical line ventrally. In some individuals, a pale yellow extension of this line runs down to the belly.
The head has few markings. There is a reflective blue line running diagonally behind the eye and small blue spots alongside. There is a black spot behind the eye. There is a wedge-shaped black patch running parallel to the jaw starting at the angle of the mandible. The upper lip and adjacent face are ridged and variegated.
Fin design
The dorsal fins have a blue-edged red upper margin, the result of a line of red spots on the top of each spine. The second dorsal fin extends to the tail.
This margin is continued onto the translucent caudal fin, which is elaborately shaped, with red streaks, and blue-edged red spots along the top. The anal fin is translucent yellow-grey with an orange margin and narrow blue submarginal line
The pelvic fins are pale yellow-grey. The pectoral fins are colourless.
Diagnostic features
This goby looks different from most others in its genus in being a very plain fish with characteristic dorsal freckling between the bars and distinctive red fin margins.
It can be surprisingly difficult to distinguish from A stenotaeniata in photographic images by the body and fin features. The best way to tell them apart is by the black spot behind the eye, the wedge-shaped black patch running parallel to the jaw and the ridged and variegated upper lip. Habitat and ecological preferences are also different.
Similar species
A stenotaeniata
A gymnocephala
Both are differentiated by head design features.
Taxonomy
Etymology Latin rubri=red, marginata = margined. (The dorsal fin rays)
Citation Mohlmann and Randall 2002 Bull. Raffles Mus. 50(1) 216.
Type locality Watson’s Bay, Lizard Island.
Natural History
Habitat Moderately coarse sand at the edge of a fringing reef or among scattered small coral rock outcrops at 5 to 25 metre depths.
Behaviour
In the course of a period of observation, the eye surround can be seen to change from pale to black. We do not know the significance of this. It may be a response to anxiety. or it may be a signal to other shrimp gobies in the vicinity. The same thing is seen in other shrimpgobies.
Displaying with fins out and jumping up and down
Cleaner Shrimp The shrimpgoby sits quietly at the burrow entrance while a cleaner shrimp (Anclyomenes species) cleans along its back.
Distribution
Published Distribution: Indonesia, Philippines, Malaysia, Papua New Guinea, Australia: Ashmore Reef through Great Barrier Reef to Morton Bay and New Caledonia
Our records: Solomon Islands: Ghizo, Nggella, Santa Isabel, Soghangola Island and Maravagi Bay. Papua New Guinea: Kimbe Bay and Normanby Island. Indonesia: Batanta, Kabui Bay. Australia: Great Barrier Reef Ribbon Reefs 3 and 9, Tongue Reef, Michaelmas Cay, Lizard Island, Low Isles.
Associated Shrimp species
Associated Shrimps (six shrimps)
Banded Snapping Shrimp, Alpheus species 1
Black-sided Snapping Shrimp, Alpheus cf djeddensis
Pink Pyjama Snapping Shrimp, Alpheus ochrostriatus
Red Pyjama Snapping Shrimp, Alpheus ochrostriatus
Red Snapping Shrimp, Alpheus species 9 (Image from video)
Tiger Snapping Shrimp, Alpheus bellulus