The sailfish enters the LRT with the swordfish, but closer to the anchovy

Updated January, 17, 2021
with new taxa and new scores nesting Istiophorus, the sailfish, with Elops, the anchovy. These give rise to the swordfish, Xiphias, and the European eel, Anguilla. All are derived from the Late Jurassic, Bavarichthys.

Traditionally the sailfish
(Istiophorous) is considered a billfish, closely related to the marlin (Makaira), and then the swordfish (Xiphias).

By contrast, 
the large reptile tree (LRT, 1641 taxa then, now 1793 taxa) nests the sailfish with the anchovy, Elops, close to the swordfish, Xiphias.

Figure 1. Istiophorus, the sailfish, nests with the cobria (Fig. 2) in the LRT, not with the swordfish.

Figure 1. Istiophorus, the sailfish, nests with the cobia (Fig. 2) in the LRT, not with the swordfish.

Istiophorus platypterus (Shaw 1792 in Shaw and Nodder 1792; 3m) is the extant sailfish and a relative of Rachycentron, the extant cobia (above). The rostrum is extended, convergent with another fast, open ocean predator, the swordfish, Xiphias. The anterior dorsal fin is larger than the lateral area of the fish itself. Teeth are absent. The pectoral fins are long and slender. The anal fin is divided in two. The vertebral column is composed of relatively few, but large vertebrae.

Wikipedia reports,
“they [billfish] are also classified as being closely related to the mackerels and tuna within the suborder Scombroidei of the order Perciformes.”

By contrast,
billfish nest with anchovies in the LRT. The mackerel (genus: Scomber) also entered the LRT alongside Thunnus, the tuna, which it greatly resembles in every regard, other than size.

Figure 5. Skull of the sailfish, Istiophorus. Compare to Elops in figure 6.

Figure 2. Skull of the sailfish, Istiophorus. Compare to Elops in figure 6.

Figure 4. Swordfish ontogeny (growth series). Hatchings have teeth, a short bill and an eel-like body still lacing pelvic fins.

Figure 3. Swordfish ontogeny (growth series). Hatchings have teeth, a short bill and an eel-like body still lacing pelvic fins.

Figure 2. Elops is the extant anchovy. Compare to Bavaricthys in figure 1 and Istiophorus in figure 5.

Figure 4. Elops is the extant anchovy. Compare to Bavaricthys in figure 1 and Istiophorus in figure 5.

With the sailfish and swordfish gone, where does that leave the lonely barracuda?
In the LRT the barracuda nests with the similar remora (Remora) and cobria (Rachycentron), derived from the maui-mahi (Coryphaena).

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

Figure 5. Subset of the LRT focusing on ray fin fish. Eel-like taxa are highlighted.

Designed for reptiles,
the character list in the LRT is still working to separate fish as close in appearance as the swordfish and sailfish. So, please, don’t keep suggesting I expand the character list. It’s totally unnecessary.


References
Gregory WK and Conrad GM 1937. The comparative anatomy of the swordfish (Xiphias) and the sailfish (Istiophorus). The American Museum Novitates, 952:1-25.
Kaup JJ 1826.
Beiträge zu Amphibiologie und Ichthiyologie. Isis von Oken 19(1): 87-90.
Shaw G and Nodder FP 1792. Xiphias platypterus: The broadfinned swordfish. The naturalist’s miscellany, plate 88. 28 p. (Application to validate the nomen oblitum for the Indian Ocean sailfish (genus Istiophorus)

wiki/Istiophorus
wiki/Rachycentron

3 thoughts on “The sailfish enters the LRT with the swordfish, but closer to the anchovy

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