Hoplerythrinus enters the LRT

Updated January 19, 2021
with a revision of the LRT that now nests this taxon between the piranha, Serrasalmus, and Xiphactinus, the giant Cretaceous predator.

The aimara, trahira, gold wolf fish, etc.
(genus: Hoplerythrinus unitaeniatus (hop-ler-rie-thry-nus) ) swims in South American rivers.

Figure 1. The araimaia, Hopolerythrinus, enters the LRT with the piranha, Serrasalmus.

Figure 1. The araimaia, Hopolerythrinus, enters the LRT with the piranha, Serrasalmus.

Figure 3. Araimaia (Hoplerythrinus) skull.

Figure 3. Araimaia (Hoplerythrinus) skull.

Hoplerythrinus unitaeniatus 
(originally Erythrinus unitaeniatus Spix and Agassiz 1829) is the extant gold wolf fish or aimara, found in South American rivers. Like Amia, this taxon does well with stagnant, oxygen-poor water by gulping air.

Figure 2. Xiphactinus fossil. The famous fish-within-a-fish. Note the posterior pelvic fins.

Figure 2. Xiphactinus fossil. The famous fish-within-a-fish. Note the posterior pelvic fins.

The clear resemblance of Hoplerythrinus to the bowfin, Amia
(Fig. 5), is due to homology. The two are closely related. Note some bones split. Others appear de novo. Others expand/shrink.

Figure 8. Subset of the LRT focusing on ray fin fish. Eel-like taxa are highlighted.

Figure 8. Subset of the LRT focusing on ray fin fish. Eel-like taxa are highlighted.

The atypical contact between
the premaxillary ascending processes and the frontals (splitting the nasals, Fig. 2) in Hoplerythrinus recalls a similar morphology in Amia (Fig. 5).


References
Spix JB von and Agassiz L 1829. Selecta genera et species piscium quos in itinere per Brasiliam annis MDCCCXVII-MDCCCXX jussu et auspiciis Maximiliani Josephi I…. colleget et pingendso curavit Dr J. B. de Spix…. Monachii.

wiki/Hoplerythrinus_unitaeniatus

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