Observer: I found this spider in my front patio in the north of Ensenada, Mexico (Figure 1). By the images available online, I think it's similar to the species of tarantula Aphonopelma johnnycashi. The mosaic in the background measures approximately 30 cm (12") per side.
Expert in arachnids:
When identifying tarantulas, on several occasions it has been difficult to identify the species basing ourselves only on photographs (unless they present a very distinctive characteristic). This is due to the fact that reproductive organs are used to define the species, and these can be difficult to appreciate in photographs. In any case, the tarantulas of the genus Aphonopelma don't present any risk to humans; what I do know from what they have told me is that their bite does hurt a bit.
Generally, tarantulas don't tend to be in urban zones, but we can find them in suburban areas of Ensenada, for example, in the southern part of the city or in the peripheral colonies closest to the hills. Tarantulas are nocturnal and make burrows for shelter, for the same reason that they are animals that hardly adapt to urban zones. It's worth mentioning that when you find a tarantula at home, it's best to let it free since it doesn't pose an important threat to us.
To know more about arachnids of the city of Ensenada I recommend visiting this Facebok page “Arañas de Ensenada, Baja California”, which is administrated by the biologist Luis Carlos Hernández, who has a natural fascination for arachnids and kindly provided his opinion for this observation. On this website, citizens can publish photos of the spiders they find, in order to get help with identifying the organisms or for determining if they present any risk to human health or if they are really inoffensive (like in this case).
Luis Carlos Hernández Salgado.
Faculty of Sciences, UABC.