Aenigmachanna: a new snakehead cave fish with an odd maxilla

Aenigmachanna gollum 
(Britz et al. 2020; Fig. 1) is a newly discovered dragon snakehead, a small (12cm) extant cave fish from India. In the large reptile tree (LRT, 1755+ taxa) Aenigmachanna nests with the much larger snakehead, Channa (Figs. 2, 3).

Figure 1. The dragon snakehead, Aenigmachanna. Note the oversized maxilla (bright green) with twin dorsal processes. In vivo shown slightly larger than life size.

Figure 1. The dragon snakehead, Aenigmachanna. Note the oversized maxilla (bright green) with twin dorsal processes. In vivo shown slightly larger than life size.

The odd cheekbone of Aenigmachanna
(bright green) is a unique sort of maxilla with twin dorsal processes. No LRT ancestors have such a cheekbone until we get back to the equally vicious pirhana (Serrasalmus) and its longer, lower sister, the South American gold wolf fish (Hoplerythrinus), but those cheekbones are typical extensions of the jugal.

Channa sp. (Scopoli 1777; 25 cm to 1+m) is the extant snakehead, a predatory freshwater fish nesting here between the pupfish (Pseudorestias) and the wolffish (Anarhichas). Channa can breathe air and travel across land for short distances seeking new ponds, but this is rare as the pectoral fins are weak and poorly angled for this. Like the wolffish, the dorsal and anal fins are long. The pelvic fins are also absent. Teeth are present on the parasphenoid. In Channa the maxilla is a toothless splint.

Figure 2. Channa andrao in vivo.

Figure 2. Channa andrao in vivo.

Figure 4. Revised skull of the snakehead fish, Channa, with DGS colors applied.

Figure 3. Revised skull of the snakehead fish, Channa, with DGS colors applied. The new dragon snakehead helped inform the identity of several bones here.

Early Eocene fossils are known from this clade.
Snakehead nicknames include “Frankenfish” and “the fish from Hell”.

Aenigmachanna helped inform and repair
skull bone identities in Channa. The large open cheek area behind the eye in both taxa is filled with jaw muscles, apparently necessary for such large teeth.


References
Britz et al. 2020. Aenigmachannidae, a new family of snakehead fishes (Teleostei: Channoidei) from subterranean waters of South India. Nature.com/scientificreports 10:16081. https://doi.org/10.1038/s41598-020-73129-6
Scopoli JA 1777. Introdvctio ad historiam natvralem sistens genera lapidvm, plantarvm, et animalivm hactenvs detecta, caracteribvs essentialibvs donata, in tribvs divisa, svbinde ad leges natvrae. – pp. [1-9], 3-506, [1-34]. Pragæ. (Gerle).

More pix and taxon distribution info here.

wiki/Channa
wiki/Snakehead
wiki/Aenigmachanna
wiki/Atlantic_wolffish
wiki/Pupfish
wiki/Sarcastic Fringehead

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