Profundulus cf. balsanus

  This population is closely related with Profundulus balsanus and probably belongs to this species. For expressing this fact, it is called here Profundulus cf. balsanus. The preliminary designation Lineage "Tlahuizopa" (correct: Tlahuizapa) given by Calixto-Rojas et al. (2023) refers to its occurence in the Arroyo Tlahuizapa near the town of Tlahuizapa in the Mexican federal state of Guerrero.

  The genus Profundulus was erected by Carl Leavitt Hubbs in 1924 after recognizing differences to Fundulus in "several important respects". For him, "as the more generalized members of Fundulus, Cynolebias and some other american genera of the Cyprinodontidae, as well as the less specialized Goodeidae, resemble the species of Profundulus in habitus, it seems not improbable that Profundulus, of all american genera, diverges least from a general ancestral cyprinodont type." The ancient Greek word "pro" (πρό) means "before", so the name of the genus refers to this fact, that Hubbs believed that the members of Profundulus are basal to Fundulus. The genus Fundulus again can be derived from the Latin word "fundus" which means bottom; the suffix "-ulus" is also of Latin origin and indicates a diminutive. The genus Profundulus can therefore be translated with "before or older than the little one from the bottom". This odd name is in connection with the English expression "mud minnow" for Fundulus heteroclitus, with the name originating from its method of avoiding freezing during the winter months. When winter arrives, they burrow their way into the sediment and mud at the bottom of their habitat.