Hypseleotris notata
Drysdale Gudgeon
Species Summary
Quite possibly Australia’s most poorly known freshwater fish, Hypseleotris notata is known from just two specimens, collected in 1975 from rapids on the Drysdale River, in the remote Kimberley region of Western Australia, some 4 km above its junction with Forest Creek — a site accessed at the time by helicopter. It is listed as Critically Endangered by the IUCN.
Etymology
The species name notata is the feminine form of the Latin notatus, “marked,” referring to the vertical, chevron-shaped dark brown bands along the gudgeon’s sides. It was originally described in the now-defunct genus Kimberleyeleotris, before a 2022 phylogenomic study showed it to be nested within Hypseleotris.
A Mystery Still Unsolved
No live photograph of Hypseleotris notata is known to exist, and no specimen has been seen since the original 1975 collection despite two dedicated search efforts — by Gerry and Mark Allen in 1998, and by James Shelley and Matthew Le Feuvre during 2012–14 fieldwork for a Kimberley field guide. The current working hypothesis is that the species lives primarily in one or more inaccessible tributaries rather than the sampled main channel, and that much of the mid-Drysdale catchment remains effectively unsampled due to the difficulty of reaching it. Almost nothing is known of its biology — temperature tolerance, breeding size and spawning behaviour are all simply recorded as “unknown” in the most recent published account — making this one of the few genuine blank spots left in the knowledge of Australia’s native fish fauna.
Compiled for Home of the Rainbowfish from ANGFA sources: P. J. Unmack & C. Scharpf, “Fish in Focus: Drysdale Gudgeon Hypseleotris notata”, Fishes of Sahul 37, December 2023, pp. 2073–2074.