Abstract We present the first record for Loxosceles gaucho Gertsch, 1967 in the Amazonian region of Brazil. Four males, fifteen females and forty-nine immatures were collected in different places in Manaus, Amazonas, Brazil. This is the third species of Loxosceles reported in the Amazon region along with L. amazonica Gertsch, 1967, and L. similis Moenkhaus, 1898. This is the first record of an invasive species of a venomous animal in the state of Amazonas, Brazil, which is noteworthy due to its synanthropic habit, which increases the risk to the local population.

A short inventory of the mammalian fauna occurring in an area of the Marajó Island was performed during the rainy season. In addition to captures by using Sherman and Tomahawk traps, and mist-nets, indirect evidence was considered, e.g. finding of body fragments of specimens, vocalization, and testimonies from local people. A total of 57 species (22 families) was recorded. None of them is presently considered as critically endangered according to the IUCN criteria. First confirmed record for the fruit-eating bat Platyrrhinus brachycephalus (Rouk & Carter, 1972) in the Marajó archipelago. Additional surveys conducted in both wet and dry seasons are required for improving the profile of richness and diversity of mammal species in that region.