Study reveals cryptic species in Campylomormyrus

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A study of the electrical impulses released by two Campylomormyrus elephant nosed fishes has suggested that one of the species contains more than one species masquerading as another morph.

The study, which has just been published in the journal Molecular Phylogenetics and Evolution looked at the electrical discharges released by Campylomormyrus numenius and C. tamandua, two species of weakly electrogenic mormyrids found in West Africa.

The two species are sympatric and occur together in the same habitat, so have slightly different Electric Organ Discharges (EODs), which also vary as the fish get older.

The Long-nosed elephant fish, C. tamandua, has just one type of EOD pattern and it remains the same no matter how old the fish is. However, in the specimens identified as C. numenius the scientists found that there were three different EOD waveforms among adult males, but a single EOD waveform among all juveniles.

Closer investigation on the genetics of the elephant noses revealed that what appeared to be a single species, C. numenius, might actually contain a number of cryptic species or morphs that had previously gone unrecognised.

The scientists produced a molecular phylogeny, based on 2222 base pairs from the cytochrome b, the S7 ribosomal protein gene, and four flanking regions of unlinked microsatellite loci, and found that there were two well-supported clades of fish within those examined.

The team wrote: "The correct assignment and the high pairwise FST values support our hypothesis that these groups are reproductively isolated. We propose that in C. numenius there are cryptic species, hidden behind similar and, at least as juveniles, identical morphs."

How many Campylomormyrus?The genus Campylomormyrus was erected by Bleeker in 1874 and currently contains around 14 species including the following, whose distributions can be viewed on Practical Fishkeeping's Fish Mapper application.

Campylomormyrus bredoi

Campylomormyrus cassaicus

Campylomormyrus christyi

Campylomormyrus curvirostris

Campylomormyrus elephas

Campylomormyrus luapulaensis

Campylomormyrus mirus

Campylomormyrus numenius

Campylomormyrus orycteropus

Campylomormyrus phantasticus

Campylomormyrus rhynchophorus

Campylomormyrus tamandua

Campylomormyrus tshokwe

For more information on the elephantnoses see the paper: Feulner, PGD, F Kirschbaum, C Schugardt, V Ketmaier and R. Tiedemann, 2006. Electrophysiological and molecular genetic evidence for sympatrically occuring cryptic species in African weakly electric fishes (Teleostei: Mormyridae: Campylomormyrus). Molecular Phylogenetics and Evolution 39: 198-208.