Final answer:
The mimicry observed by biologists in venomous snakes in Texas with similar markings is described as Müllerian mimicry, where multiple toxic species share warning colorations for mutual benefit.
Step-by-step explanation:
Biologists observing two highly venomous snakes with similar markings in Texas would describe the mimicry as Müllerian mimicry. This is because both species are actually venomous and have similar warning colorations as a defense mechanism against predators, such as owls. In contrast, Batesian mimicry occurs when a non-toxic species mimics the warning coloration of a toxic species, as seen in certain insects that resemble venomous wasps or bees. Müllerian mimicry is beneficial to all the species involved, as predators learn to avoid them all due to the shared unpleasant or dangerous characteristics.