Since the original description, the systematic status of the Agroecomyrmecini tribe has been the focus of intense debate. Bolton (2003) was the first to suggest the taxonomic instability of
Tatuidris within Myrmicinae and raised the genus to the level of a new subfamily, the Agroecomyrmecinae, suggesting the Agroecomyrmecinae might be the sister taxon to Myrmicinae. This assessment was based on these diagnostic characters: • large mandibles with mandibular masticatory margins that oppose at full closure but do not overlap • eyes at extreme posterior apex of deep antennal scrobes •
clypeus very broadly triangular, broadly inserted between the frontal lobes • antennal sockets and frontal lobes strongly migrated laterally, far apart and close to lateral margins of the head •
mesotibia and metatibia with pectinate spurs • short and compact mesosoma • a sessile
petiole, in posterior view the
tergite and
sternite not equally convex • an abdominal segment III (postpetiole) without tergosternal fusion, segment large and very broadly articulated to segment IV, • a helcium in frontal view with the sternite bulging ventrally and overlapped by the tergite • an abdominal segment IV with a complete tergosternal fusion, • abdominal segment IV with a stridulitrum on the pretergite • the sternite of abdominal segment IV is reduced, the tergite is much larger than the sternite and strongly vaulted The subfamily rank of the armadillo ants was reassessed by Baroni Urbani & de Andrade (2007) in their last systematic assessment of the
dacetines. They analyzed a morphological dataset that included former dacetines,
basicerotines,
phalacromyrmecines, and
Tatuidris, as well as other non-Myrmicinae taxa such as the Australian genus
Myrmecia and the Neotropical genus
Pseudomyrmex. This work was the first attempt to include
Tatuidris as a terminal taxon in a morphological cladistic analysis. In their study, Baroni Urbani & de Andrade (2007) identified six morphological
synapomorphies shared between
Tatuidris and the dacetines, justifying the inclusion of the genus within Myrmicinae. These characters included: • mandibles at rest opposing at least in part, instead of crossing • a mandibular-torular index < 130 • reduction of maxillary palps from double-jointed to single-jointed • reduced male mandibles • presence of a two-segmented antennal club • reduced number of antennal joints In addition, two
autapomorphies (a differently shaped petiolar
tergum and
sternum, and the eyes at or close to the apex of the antennal scrobe) separated
Tatuidris from all other extant ant genera included in their study. Unlike
phylogenetic studies based on morphological traits, molecular analyses of the internal phylogeny of the ants have given strong evidence that the armadillo ants are neither closely related to nor nested within the Myrmicinae. Brady
et al. (2006), Moreau
et al. (2006) and Rabeling
et al. (2008) reconstructed phylogenetic trees with the
agroecomyrmecines inside the 'poneroid' group of subfamilies, close to the
Paraponerinae, and gave support for the exclusion of the genus from the Myrmicinae, a subfamily located inside the 'formicoid' clade. Given the early appearance of the Agroecomyrmecinae in the geologic record, the similarities of armadillo ants to Myrmicinae were hypothesized to represent convergence and/or retention of
plesiomorphic forms. Recently, Keller (2011) challenged the phylogenetic relationships of the
poneromorph subfamilies (including
Tatuidris).
Distribution According to Brown & Kempf (1967), agroecomyrmecines were probably widespread in both hemispheres during the early
Tertiary.
Agroecomyrmex is known from Early Eocene,
Lutetian,
Baltic amber dating to 44 million years (
Myr) ago, and
Eulithomyrmex from
late Eocene,
Priabonian,
Florissant shale (34.1 Myr ago) in present-day
Colorado,
United States.
Tatuidris, rare but broadly distributed, inhabits the leaf litter of
Neotropical forests in Central and South America, from
Mexico to
French Guiana, central
Brazil, and
Amazonian Peru.
Ankylomyrma is known only from Western Africa. ==Notes==