Taxonomy issues
2017: Huber's 33 Taxonomy issues

What are todays biggest challenges for a better knowledge of Killifish (oviparous Cyprinodontiformes)?

Dr Jean H. Huber
Museum national d'Histoire naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France.

Techniques and approaches in Systematics have strongly evolved in recent years for fishes and notably Killifishes (Pisces: oviparous Cyprinodontiformes) follow these trends. Thanks to computer software, researchers have become more analytical, bringing more sharply defined or extracted data from their observations. This concerns not only molecular techniques (DNA, RNA, from nucleus or mitochondria) obviously, but also morphology, osteology and lately behaviour. As a result of the availability of more numerous and sharpened data, systematics tend to split more and more, with the limit of differentiation being at the level of human eye, at least within the Linnaeus binominal nomenclature. To progress towards this asymptotic limit, 33 "biggest challenges" in terms of systematics are listed that remain unresolved for older names and an urgent call is given to win another challenge concerning "missing comparative diagnosis". Finally another type of challenge is proposed for action to expert and/or curious aquarists, according to 4 perspectives of cooperative contributions: documentary, collecting trips, breeding and behaviour.
Rivulus (Anablepsoides) urophthalmus

Rivulus micropus

"it seems a desperate case"

Pterolebias zonatus

"Cyprinodon" martae

"the single type clearly does not correspond to a Cyprinodon fish"

Fundulopanchax spoorenbergi

F. spoorenbergi

Pachypanchax omalonotus

P. nuchimaculatus

a difficult case, because the single type, rather distinctive [Huber, J.H. 1998a. Miscellaneous Notes on some Systematic Difficulties Regarding old World Cyprinodonts. J. Amer. Killifish Assoc., 31 (1): 3-17, 28-32]

Aphyosemion (Mes.) cameronense "Zomoko"

R. xanthonotus A.trilineatum

Rivulus xanthonotus and a final status for Aphyosemion trilineatum

Austrolebias wolterstorffi

schreitmuelleri : Megalebias, Austrolebias

"all 3 authors agree on one issue : the fish does not originate from Rio in Brazil, but from Uruguay"

Cynolebias perforatus

Cynolebias porosus

"Cynolebias microphthalmus, that Costa sees as distinct, is still living not far …"

Aphanius dispar dispar

Laciris pelagica, Aphanius apodus

" all known localities, it is extinct : the only solution is to discover a brand new locality in Algeria..."

Pantanodon stuhlmanni

Pantanodon madagascariensis, Millerichthys robustus

"both cases are similar because these 2 fishes are extremely important in the understanding of Killifish phylogeny (both are probably very primitive because they belong to very primitive areas) ; the problem is not their type localities that are not too difficult to reach"

Rivulus ornatus

Rivulus: obscurus, ornatus

"If the 2 fish are identical, then (ICZN law of first reviser) ornatus has priority over obscurus ; if they are distinctive, then the 2 names remain valid..."

It's bualanum not elberti

Aphyosemion bualanum

no solution from the renewed study of the single type : it has been smashed for unknown reasons ; to solve that issue, only successful collections around Bouala {6.417N;15.583E}, in Central African Republic, are required, but this is a challenge : a remote place in highlands (1200 m altitude) with no primary forest

Aphyosemion (Mes.) striatum

A. escherichi/microphtalmum

Aphyosemion escherichi vs. A. microphtalmum issue (linked to Plataplochilus ngaensis)

"Seegers believes that it is a senior synonym of microphtalmum and Huber is cautious and does not find morphological differences with striatum"


deltaensis, gularis, fallax, kribianus, schwoiseri

"Killi-Data online opts for a conservative situation, considering deltaensis and gularis as valid, kribianus and schwoiseri, as valid too, and fallax as a nomen dubium), pending Huber's publication ; no doubt that this will not be the end of the story ; apart from the renewed study of preserved material in Museums, the target is indeed an in-depth sampling of annual forms of that genus in southern Nigeria ; there is little doubt that the discontinuity in populations of sjoestedti in western Nigeria and in northwestern Cameroon does not reflect reality : between west of the mouth of Niger river and the Cameroon boundary there must be populations of large annual Fundulopanchax species with a median band on sides of both sexes, if not deltaensis …"

Fundulopanchax walkeri Purzl Loc 9

Fundulopanchax: walkeri, spurrelli

"...the first 2 taxa are unknown live from their type localities in Ghana since their description and the type locality of the third is an aquarium import ; the first duty would then be to fill these "holes" with hard data and live fish..."

Fundulopanchax powelli

Fundulopanchax powelli

"however, only preserved juveniles are known and first attempts to re-collect the fish, there, did not succeed ; knowing the dynamisms of fish exporters in Lagos, active correspondence and money, at least, should be a spur to deliver a solution for this very special fish, probably primitive and a key to the understanding of the huge speciation in the Niger delta…"

Epiplatys bifasciatus

Epiplatys bifasciatus/spilargyreius

"...there are strong suspicions that a viviparous Epiplatys species is available in eastern Africa ; it is unknown if it will be identifiable to bifasciatus, or to marnoi (a present synonym of spilargyreius), but it is a fascinating venture…"

Epiplatys barmoiensis

Epiplatys lokoensis

"this case is also apparently simple like powelli ; recollections of the fish in the very limited area of Sierra Leone (Bonkorkon, west of Port Loko, Port Loko district) should allow to re-study the fish and disclose if the describers were right to erect a new name"

Nothobranchius orthonotus

N. orthonotus

Nothobranchius mkuziensis, orthonotus and rubroreticulatus

"...Wildekamp has proposed that the status needs a re-evaluation ; it may be a distinct species related to rachovii, anyhow clearly not a junior synonym of orthonotus as previously thought..."

Poropanchax normani

Poropanchax normani

"... and the Angolan lampeyes : this case is an old one, since Poropanchax normani, and Lacustricola mediolateralis, Lacus. nigrolateralis, Lacus. (?) macrurus have never been collected live from their type localities and their descriptions are more than 50 years old..."

Rivulus holmiae

Rivulus: holmiae, lanceolatus

"...that apparently cannot be re-collected despite major efforts in recent years"

Aphyosemion elegans

Aphyosemion: elegans, decorsei

" not surprisingly both are unknown live from their type localities"

Aphyosemion: splendidum

splendidum, batesii, kunzi

"...has shown from in-depth samples in Gabon or is the picture much more complex (with 2 or 3 species being valid) as aquarists tend to believe ? Only many DNA samples may allow a better understanding of these relict fishes that are semi-annuals, but not close to Fundulopanchax..."

Hylopanchax stictopleuron

Hylopanchax: silvestris, stictopleuron

"...only many DNA samples may allow a better understanding of these relict fishes that pushed the Hypsopanchax phenotypes (with several valid names !) to the periphery..."

Epiplatys: nigricans,chevalieri

Epiplatys: nigricans,chevalieri

"and neither molecular studies, nor detailed morphological measurements have been performed on these populations ; it is totally insufficient…"

Epiplatys multifasciatus

A. ferranti, A. lujae, E. multifasciatus

25- Aphyosemion ferranti, A. lujae, Epiplatys multifasciatus : this is an old case since the 3 names were described from the same locality (near Kondué, Kasai, Congo (today Zaïre) {4.983S;23.300E}; to collect there would allow a proper identification of the 3 phenotypes, an assignment to a phylogenetic group for ferranti and a new detailed study of the multifasciatus superspecies ; and by the way, another series of live discovery is to be found not "far" for the first time : Hypsopanchax jubbi (Near Zambezi source, Mwinilunga, Zambia {11.117S;24.117E}) and H. jobaerti (Lula, Mosanji river, S.W. Zaïre {7.217S;23.117E}), plus Nothobranchius species, N. (Zono.) brieni (Bukama, Shaba Province, S.E. Zaïre {9.208S;25.850E}), N. (Zono.) malaissei (1.5 km E. Kabiashia, S. Lake Moero, S.E. Zaïre {10.267S;28.133E}), N. (Zono.) polli (Near Mwadingusha, Shaba, S.E. Zaïre {10.750S;27.250E}) ; really an un-deserved situation …

Pterolebias longipinnis

Pterolebias bokermanni, luelingi and the rediscovery of longipinnis

"the observed variations in morphology and colour pattern, began to suspect that there may be more than one species there"

Scriptaphyosemion liberiense "Gbarma RL97 EP82"


melantereon : Scriptaphyosemion vs. Epiplatys

"...renewed study of the material in Philadelphia museum would be the simple answer, easy if only the types were fully adult fish…"

Cynopanchax bukobanus

L. atripinna, bukobanus

Lacustricola atripinna, bukobanus

"...hypothesized to be a senior synonym from bukobanus, from Bukoba, also in Tanzania {1.333S;31.817E} ; a simple, but unavoidable comparative study of the types of the 2 taxa, both in Berlin Museum, is a prerequisite before in-depth live collections…"

Fundulus kansae zebrinus

Fundulus kansae and zebrinus

"...DNA evidence that the fish populations over the huge range may correspond to 2 distinct species (northern populations assigned to kansae, southern populations to zebrinus) ; both names have no serious type locality..."

Aphyosemion exiguum "ADK 10/305"

Aphyosemion exiguum, Epiplatys nyongensis

"... the single type of both nyongensis and sangmelinensis should then be re-studied to clarify this point ; another difficult (not anecdotal any more !) task for "old fashioned" (also aging) ichthyologists, but this time in London and Berlin and a necessary comparison with topotypic live material …"

PAN from "an island off Singapore"

blockii, panchax, siamensis, andamanicus

Aplocheilus: blockii, panchax, siamensis, andamanicus

"...the taxonomic situation is indeed below standard ; most names have been described during the second half of the 19th century probably from colonial harbours (but without certainty) or from aquarium imports without precise origin (and often types are missing in addition..."

Orestias luteus


" the issue for these Andean fishes that have been uplifted by 4000 meters with the upheaval of the South American Cordillera, some 30 million years ago is : speciation"

Fundulus nevadensis


Numerous names with missing types or undisclosed type material

"type material of many species have not been located..."

Copyright 2022
Richard J. Sexton