Color settles this one immediately. The arminids on this reef are pale, greenish or brown; this is the red one, running from deep red to pink, with white lines drawn lengthwise along the ridges of its back. Nothing else in the group looks like it.
The ridges themselves are the family build. Fine and parallel, running the length of the body, on a back that carries no gill plume at all: arminids fold their breathing surfaces away underneath, into the groove between the mantle skirt and the foot along both flanks, so the upper surface is a closed ribbed shield. They plough sand with a broad sensory veil held out in front, hunting octocorals, and they spend daylight buried or under cover.
Five centimeters (2 in), and photographed on the sandy ground at Abu Dabab.
One thing to know before searching for images. This animal has moved genus. The regional book and GBIF both print it as Dermatobranchus rubidus, which is the name used here, but the taxonomic databases and the photographic sites now file it under Armina rubida, and that is where its pictures are. Search on the printed name and you will find very little; search on Armina rubida and there are a couple of dozen.
- red to pink body, which no other arminid here has
- white lines running lengthwise along the ridges
- five centimeters
- on sand near soft corals, out after dark
