Another seahorse sister: the electric elephantfish (Gnathonemus)

How was this obvious relationship overlooked for so long?
No other fish has such a long, tubular snout with such a tiny mouth at the tip (Figs. 1,2), except taxa from the seahorse clade. This is homology, not convergence.

Gnathonemus curvirostris (Gill 1863; Fig. 1) is the extant elephantfish, a member of the clade Mormyridae, ranging in size from 5cm to 1.5m. Traditionally considered a sister to Osteoglossum (Fig. 2) here it nests as a sister to seahorses (Fig. 3), sharing a long tubular snout, vertical maxilla (here rotated back to the horizontal plane) fused intertemporal and supratemporal along with several other seahorse-like traits. Compare the elephantfish to the untested pipefish, Aulostomus (Fig. 3), below.

The cerebellum of the elephantfish is greatly enlarged. This slow, brackish water micro-predator uses electrical impulses to find tiny prey in cloudy waters convergent with electric eels.

Perhaps the key to understanding elephantfish
is to realize they ultimately arise from sticklebacks (Fig. 3) and pipefish. The posterior half of both taxa are nearly identical. Adapting to murky waters, the elephantfish developed a long, curved rostrum and electrosensory abilities.

Yes, elephantfish and seahorses look wildly different on the outside,
but stripped of their skin, no other tested taxon nests closer to the seahorse than the elephantfish. This is the humble beauty of a phylogenetic analysis that recovers a nearly fully resolved tree of life with high Bootstrap values.

By lumping elephantfish with seahorses,
the LRT is lumping and splitting traditional fish clades into new clades, just as it lumped and split bird, mammal and other clades. Earlier we looked at yet another traditionally overlooked seahorse sister, the giant oarfish (Regalecus).

References
Gill TN 1863. Notes on the labroids of the western coast of North America. Proc. Acad. Nat. Sci. Phila. v. 15: 221-224.

wiki/Mormyridae