The new and the known:describing freshwater fish species

September 2001

The discovery of new vertebratespecies is a very rare event in Australia.Rainforest CRC researcher Dr BradPusey has recently described not one,but two new species of freshwater fishendemic to the Wet Tropics region.Their description sheds light on theuniqueness and antiquity of the fauna.

Describing a new speciesIn 1993, Brad and his co-workers, MarkKennard of Griffith University andAndrew Sheldon of the University ofMontana, surveyed the fish fauna ofthe Bloomfield River as part of a largerstudy of the freshwater fish diversityof the Wet Tropics. Among the manyinteresting fishes collected, were 13specimens of a very odd looking littlefish. They recognised that the fishbelonged to the family Percichthyidae,which contains the well-knownMurray Cod and Yellowbelly, but werepuzzled as to its specific identity. Evenmore puzzling was the fact that noPercichthyidae had ever been collectedfrom tropical Australian freshwaters.

Additional specimens were collectedin 1994 and laboratory work on themcommenced. The specimens weremeasured, dissected and x-rayed,theirphysical features were counted andspecimens genetically tested forcomparison with other species withinthe family. The result – not only a newspecies but a new genus as well!Groups of closely related species areplaced in a genus. A formal descrip-tion was prepared and circulatedamongst Australian fish taxonomistsbefore being accepted by the special-ist journal Ichthyological Explorations ofFreshwaters. The species descriptionfinally appeared in print in 2001. Along time but worth the wait.

Naming the speciesThe name selected for the new specieswas Guyu wujalwujalensis. The genusname is a departure from the usualpractice of using latin.

We were most fortunate in beinggranted permission by the Kuku-

Yalangi Aboriginal people to use atraditional word in the description andalso in being so generously grantedaccess to the beautiful BloomfieldRiver. The genus name is derived fromthe Kuku-Yalangi word “kuyu” whichmeans freshwater fish. The letter “k”is pronounced phonetically as “g” inAboriginal languages. Kuyu is usedsimilarly by other language groups ofnorth Queensland. The species namewujalwujalensis denotes that the newspecies occurs near the township ofWujal Wujal. It was felt that the namenot only suits the new species well butalso conveys some impression of thestrong link between Aboriginal peopleand their relationship with the land.

Guyu wujalwujalensis occurs nowhereelse but the Bloomfield River and isfurther restricted to only that part ofthe river between the downstreamBloomfield Falls and the upstreamRoaring Meg Falls. As such it has oneof the most geographically limiteddistributions of any of the region’sfreshwater fishes. Its origins are prob-ably very ancient, and may date backto the late Cretaceous, some 70-100million years ago. It may representwhat remains of a previously morewidespread fauna that is now confinedto temperate and sub-tropicalAustralia. Given these factors, it has avery high conservation significanceand is therefore listed as “Vulnerable”by Environment Australia. It is likelythat the single greatest threat to itscontinued existence is the introductionor translocation of fish into theBloomfield River.

Bloomfield River Cod (Guyu wujalwujalensis)

Photo: Mark Kennard

Redescribing a known speciesThe second fish proved more an exer-cise in redescribing than describing.This was the khaki bream (Hepahestustulliensis) another endemic Wet Trop-ics species superficially similar to theblack bream or sooty grunter(Hepahestus fuliginsosus), a widespreadspecies of angling and culinaryrenown. While it has long beenrecognised as being distinct by anglersand some fisheries personnel, thespecific identity of the khaki breamhas remained a mystery. Brad and hisco-worker, Dr Gerry Allen of the West-ern Australian Museum, commencedwriting a formal description but indoing so found they had been beatento the punch, by over 100 years!

Duplication and errors when speciesare describedThe khaki grunter was originallydescribed, as H. tulliensis, by C.W. DeVis in 1884. For reasons which remaindifficult to fathom, the name waseither never adopted or rapidlydropped out of usage. In a 1978revision of the family Terapontidae,(the grunters) it was considered not tobe a valid species, but rather a“synonym” of another species H.fuliginosus.

Synonomy occurs when two differentauthors describe and attribute differ-ent names to the same species.Synonomy in Australian freshwaterfishes occurred fairly frequently in thelate 19th century when many newspecies were being described butcommunication between researcherswas limited.

In such cases, historical precedencedetermines which name is valid. Therecognition of synonomy usuallyoccurs when a taxonomic group suchas a family or genus is being revised.

Such revisions are necessary to ensurethat nomenclature remains correct andaccurate and to ensure that taxonomicassociations, such as species withingenera or genera within families,accurately reflect evolutionary history.Sometimes this process may result inlong familiar names being changed tosomething new. It may result inlumping, where species formerlyconsidered distinct are collapsed intoa single species, or alternatively insplitting, where a single species isdivided up into several new species.On occasions, the decisions madeduring revisions may be in error, suchas the recognition of the synonomy ofH. tulliensis and H. fuliginosus. In thiscase, the error arose because of afailure to examine specimens of bothspecies from the Wet Tropics region.

Why describe species at all?What is the relevance of this rathertechnical and specialised activity?

In addition to its importance to thepurely scientific pursuit of under-standing the evolutionary history andbiogeography of different groups, therecognition of what constitutes anindividual species has more immedi-ate and practical concerns.

Many management strategies arefocused on individual species. If wedon’t know what species we aretrying to manage, how can we do soeffectively? For example, H. tulliensisis found nowhere else but the WetTropics, in contrast to the more wide-spread distribution of its relative H.fulignisosus. Accordingly, H. tulliensismust be viewed as having a higherconservation significance. Moreover,the reproductive ecology and habitatrequirements of H. tulliensis differ fromthat of H. fuliginosus. Managementguidelines such as minimum sizelimits and bag sizes designed for theprotection of one species may notadequately protect, and may in fact bedetrimental, to another species if theyare not recognised as being distinct.

Two of the region’s endemic fishesnow have scientific names. Otherendemic fishes of the region are yet tobe formally described, however. Theseinclude fishes from such diversegroups as rainbowfish, hardyheads,catfish and gobies. The work goes on!

For more information contact:Dr Brad PuseyFaculty of Environmental ScienceGriffith UniversityNATHAN, QLD 4870Phone and Fax: (08)9751 2265Email: bpusey@westnet.com.au

Khaki bream (Hephaestus tulliensis)

photo: Gerry Allen