Lyrognathus giannisposatoi sometimes called the Sumatran stout leg tarantula is a tarantula which can be found in Mesuji Regency, Sumatra, Indonesia.

It was first described by Steven C. Nunn, Rick C. West in 2013, and is named after Gianni Sposato, who helped with Selenocosmia material, and was of great help to the authors.

[1][2] They can be distinguished from all of the Lyrognathus genus, because of its bigger size and a more robust body, and for its preference of lower altitudes, which differs from most of the genus.

[2] In females the carapace is a dark brown with some orange almost pinkish striping.

Males have roughly the same coloration though it is significantly darker.