Anableps, the four-eyed fish, revised

Some fish in the LRT continue to be revised,
hopefully this time for the last time.

Today,
the extant four-eyed fish, Anableps (Fig 1), dons new DGS colors that ally it more closely with Jurassic Leptolepis and extant Danio (Fig 1), the zebrafish. These two small fish with large eyes are now closer matches to Anableps despite its lower, wider skull with elevated orbits.

Figure 1. Leptolepis, Danio and Anableps compared, not to scale. ” data-image-caption=”

Figure 1. Leptolepis, Danio and Anableps compared, not to scale.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=139″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=473″ class=”size-full wp-image-85100″ src=”https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=584&h=1263″ alt=”Figure 1. Leptolepis, Danio and Anableps compared, not to scale. ” width=”584″ height=”1263″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=584&h=1263 584w, https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=69&h=150 69w, https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg?w=139&h=300 139w, https://pterosaurheresies.files.wordpress.com/2024/03/leptolepis_anableps_danio_skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Leptolepis, Danio and Anableps compared, not to scale.

The nesting of Anableps
with Danio in the Cypriniformes (= carp) follows traditions and textbooks. This time I was the last to know. That low, wide skull and dorsal eye socket in Anableps are not commonly found in other carp, but are more common among gobies, like Glossogobius.

Anableps tetrophthalmus
(originaly Cobitis anableps Linnaeus 1758, Scopolis 1777; Michel et al. 2015; 32 cm) is the extant four-eyed fish (aka: cuatro ojos), a surface predator of insects falling into Amazonian fresh waters or shallow shores where Anableps beach themselves to eat them. The underslung jaw enables this behavior. Traditionally and here Anableps is a member of the pupfish (guppy, killifish, topminnow) family. Internal fertilization (with a modified tubular anal fin) leads to live birth (viviparity) of up to 14 young.

References
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Michel KB, Aerts P, Gibb AC and Van Wassenberg S 2015. Functional morphology and kinematics of terrestrial feeding in the largescale foureyes (Anableps anableps). Journal of Experimental Biology (2015) 218, 2951-2960 doi:10.1242/jeb.124644
Scopoli GA 1777. Introductio ad historiam naturalem sistens genera lapidum, plantarum, et animalium. Wolfgang Gerle, Pragae 3-506.

wiki/Anableps