tonatiuh cualo (TR37r)
This simplex glyph shows the sun (tonatiuh) with a wedge missing, something like a pie where a piece has been eaten. An eclipse was usually called "tonatiuh cualo," literally, the sun is eaten, but indicating that part of it has gone dark. The sun here is much like the sun in the Codex Mendoza, with its quincunx shape, detailed design, and multiple colors. The gloss clarifies that this glyph represents an eclipse.
Stephanie Wood
See other examples of eclipses, below. One has the missing part darkened. But the missing wedge here might also be a way of indicating it was partially eaten. Consider the possible eclipse in the Codex Azcatitlan, where a serpent appears to be devouring a wedge shape of the sun.
Stephanie Wood
eclise del sol
eclipse del sol
Stephanie Wood
1578
Jeff Haskett-Wood
suns, soles, eclipses

tonatiuh cualo, to have an eclipse of the sun, https://nahuatl.wired-humanities.org/content/tonatiuh-cualo
el eclipse del sol
The Codex Telleriano-Remensis is hosted on line by the Bibliothèque nationale de France.
https://gallica.bnf.fr/ark:/12148/btv1b8458267s/f99.item. We have taken this detail shot from the indicated folio.
This manuscript is not copyright protected, but please cite Gallica, the digital library of the Bibliothèque nationale de France or cite this Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities Projects, 2020–present).