Free-living rather than fan-dwelling, among hydroids and algae on shallow slopes.
Thirteen to seventeen millimetres, with 12 trunk rings, 28 to 30 tail rings, a distinct raised angular coronet, small spines rather than bulbous tubercles, and fleshy filamentous appendages. The species character is a pair of wing-like truncate spines projecting sideways from each of the first two superior trunk ridges. That matters because this is the group divers get wrong: the Japanese pygmy has only one such pair, Satomi’s has different fin ray counts and flanged coronet, Walea’s has 32 tail rings and a low double-mound coronet, and Coleman’s is larger with a low rounded coronet. One thing to know: the white-and-yellow “pontohi” and the brown-banded “severnsi” that circulate as two species are one animal. They were separated on colour, colour is not diagnostic in seahorses, and across 21 sequenced specimens the genetic difference came to 0.2 per cent.
Unlike the two gorgonian pygmies this one is free-living: it is found on coralline and Halimeda algae, on hydroids, and on bryozoans, usually on current-swept walls and in fissures, and no host-matched colour change has been documented for it. Commonly in pairs and relatively active, most so in the morning and late afternoon. One brooding male carried about eleven embryos — note that several databases state this of the female, which is impossible in a seahorse and has propagated widely. Between about 3 and 25 m, from Indonesia to Japan, the Solomons, Fiji and the Great Barrier Reef.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.