128. Amblyomma triste Koch, 1844a.

Nearctic: 1) Mexico (north), 2) USA; Neotropical: 1) Argentina, 2) Bolivia, 3) Brazil, 4) Chile, 5) Colombia, 6) Ecuador, 7) Paraguay, 8) Peru, 9) Uruguay, 10) Venezuela (Kohls 1956b, Keirans 1985 b, Labruna et al. 2005 a, Nava et al. 2007, Forlano et al. 2008, Mertins et al. 2010, Guzmán-Cornejo et al. 2011, Abarca et al. 2012, Martins et al. 2014, Mastropaolo et al. 2014, Colombo et al. 2016 a, Guglielmone et al. 2021, Ossa-López et al. 2022).

As discussed under Amblyomma maculatum, difficulties attend the morphological separation of Amblyomma triste from Amblyomma maculatum. Nava et al. (2017) indicated that both names may represent the same species, and Lado et al. (2018) provided evidence to justify the synonymization of Amblyomma maculatum with Amblyomma triste, while dividing ticks from the Nearctic and Neotropical Regions into four morphotypes. However, additional studies are needed to confirm the hypothesis of Lado et al. (2018), and Amblyomma triste is treated here as a valid taxon, with a provisional geographic distribution encompassing the Nearctic and Neotropical Regions. We consider the geographic distribution of Amblyomma triste to be disjunct, no bona fide specimens having been collected from Central America, because a record from Nicaragua in Vogel et al. (2018) requires confirmation (Guglielmone et al. 2021). The same applies to the alleged records of Amblyomma triste from the Neotropical portion of Mexico in Graham et al. (1975) and Woodham et al. (1983), which were not validated by Guzmán-Cornejo et al. (2011).

Amblyomma triste was described by Koch (1844a) from female ticks collected in Uruguay, and populations from that country, as well as Argentina and Brazil, are morphologically and molecularly similar, constituting morphotype I in Lado et al. (2018). It is hypothesized that specimens of Amblyomma triste from Argentina, Brazil and Uruguay represent a valid species, but populations of Amblyomma triste from other countries may belong to novel taxa or to Amblyomma maculatum.