Someone suggested today to me that the "tiger-rump" tarantula spider I've encountered on several of my field trips might be Cyclosternum fasciatum or Metriopelma zebrata. As someone still quite new to tarantulas, I had never heard of the latter. So I did some research using Google to get more information on the Costa Rican Dwarf Tigerrump.
After looking at some pictures, I checked out the website one of those pictures was on. A Dutch website, and being Dutch myself, I had no problem with reading the information, which roughly translates to:
This 5 centimeters large species looks a lot like Cyclosternum fasciatum. However, the first stripe on the abdomen misses a part. Moreover, the legs don't have the noticable orange-brown hairs. The male doesn't have tibial hooks.
If this information is correct, then I can eliminate Metriopelma zebrata as a possible option for the tarantula spiders I have seen, since the adults are over 5 cm, and the male does have tibial spurs. As for the orange-brown hairs on the leg, clearly visible in a juvenile of this species I keep.
The question remains, however, am I seeing Costa Rican tiger-rumps in Mexico, or is it a different species altogether. If not, did those beautiful tarantulas got introduced into Mexico?