I know this species primarily from Winkler samples of sifted litter from the forest floor. I have seen collections from three sites on the Atlantic slope of Costa Rica: La Selva Biological Station, 1100m on the Barva Transect in Braulio Carrillo National Park, and at 800m in the Penas Blancas Valley east of Monteverde (where it appears to be sympatric with Tatuidris JTL-001). All collections have been from mature wet forest.
Mexico, El Salvador (type locality), Costa Rica, Colombia.
Molecular Biology and Genetics
Statistics of barcoding coverage: Tatuidris tatusia
Public Records: 28
Specimens with Barcodes: 31
Species With Barcodes: 1
Barcode data: Tatuidris tatusia
There is 1 barcode sequence available from BOLD and GenBank. Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen. Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Tatuidris, or armadillo ants, is a rare genus of ants consisting of a single species, Tatuidris tatusia. The ants are small in size and inhabit the leaf litter of Neotropical forests in Central and South America, from Mexico to Brazil. Discovered to be one of the earliest lineages of ants, Tatuidris is very distinctive and isolated within the Formicidae; it bears superficial resemblance to some extant genera, but these similarities are considered to be due to convergent evolution. Workers present a distinctive morphology, consisting of a shield-like head with a broad vertex, ventrally-turned heavy mandibles which do not overlap at full closure, and unique among ants – an antenna socket apparatus sitting upside-down. Little is known about the biology of the ants, but they are likely nocturnal and specialist predators.
Tatuidris was first described in 1968 and initially placed in the myrmicine tribe Agroecomyrmecini, together with two fossil genera. Since the original description, the systematic status of the tribe has been the focus of intense debate. In 2003, the tribe was raised to the level of a new subfamily, the Agroecomyrmecinae, making T. tatusia the only extant species in the subfamily.
The name Tatuidris means "armadillo ant", which is also the common name for this species; tatu comes from the Tupi and Portuguese word for "armadillo"; the specific epithet for the single described species, tatusia, is an old generic name for armadillo.
Tatuidris tatusia is the only species in Tatuidris, a monotypic genus and the only extant genus in the subfamily Agroecomyrmecinae. A new species, T. kapasi, was described by Lacau & Groc in 2012, but has now been relegated to a junior synonym under T. tatusia based on the extent of the morphological variability encountered throughout this broad geographic range. Analysis of DNA barcodes indicated a pattern of genetic isolation by distance, suggesting the presence of a single species undergoing allopatric differentiation.
This genus is very distinctive and very isolated within the Formicidae; it is considered to be one of the earliest lineages of ants, a clade from the basal polytomy for all ants. It was first described Brown & Kempf in 1968 based on two workers collected in a Berlese sample of humus in El Salvador. Due to morphological similarities, they considered it a very primitive ant and placed it in what was then a myrmicine tribe, the Agroecomyrmecini, together with ants known from Early Eocene Baltic amber (Agroecomyrmex) and late Eocene Florissant shale (Eulithomyrmex).
It bears superficial resemblance to some extant genera (Strumigenys, Ishakidris, Pilotrochus, and Phalacromyrmex) but these similarities are considered to be due to convergent evolution. Due to similarities in the habitus, Brown & Kempf (1968) linked Tatuidris to the Dacetini genus Glamyromyrmex (currently a junior synonym of Strumigenys) and Phalacromyrmex. However they concluded: "analysis of these similarities indicates [...] that they are mostly convergent and not based on close phylogenetic relationship". Further work explored the similarities of Tatuidris with Ishakidris (Bolton 1984) and Pilotrochus (Brown 1977). While these taxa share some characteristics, including an expanded head vertex, deep antennal scrobes and a compact mesosoma, the similarities were again deemed convergent.
Since the original description, the systematic status of the 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 that Agroecomyrmecinae might be the sister taxon to Myrmicinae. The subfamily rank was re-assessed by Baroni Urbani & de Andrade in 2007, this was the first attempt to include Tatuidris as a terminal taxon in a morphological cladistic analysis. In their study, Baroni Urbani & de Andrade identified morphological synapomorphies shared between Tatuidris and the dacetines, justifying the inclusion of the genus within Myrmicinae. 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.
Tatuidris is rare but broadly distributed. The ants inhabit the leaf litter of Neotropical forests in Central and South America, from Mexico to French Guiana, central Brazil, and Amazonian Peru. No collections are known from the Caribbean, Galápagos, or other islands. Most specimens and collections are currently known to occur in localities west of the Andes, with more collections tending to occur towards Central America and Mexico. Most collections come from mountainside (pre-montane) areas at mid elevations (usually 800–1200 meters of altitude). Collections from lowland Amazonia are few. Published records are few, but with the advent of litter sifting and Winkler extraction as a popular method of ant collecting, Tatuidris are not as rare as they used to seem. Although not very abundant, with frequent litter sifting they can be reliably found in Costa Rican wet forests.
The biology is poorly known; the male and female reproductive castes were described for the first time in 2012. The genus is known mainly from isolated workers found in Winkler or Berlese samples. Tatuidris workers have peculiar mandibular brushes and a powerful sting, which led Brown & Kempf to speculate that Tatuidris might be specialist predators of active or slippery arthropod prey. Until recently, no observations of live specimens were registered. Details of a first collection event of a small live colony (3 workers and 4 gynes) by Thibaut Delsinne in a mid-elevation forest in southeastern Ecuador suggest that Tatuidris may well be a highly specialized predator, as colonies kept in captivity did not accept any food item offered to them. Food items rejected by the ants included live and dead termites, millipedes, mites, various insect parts, sugar water, tuna, biscuits, live and dead fruit flies (Drosophila), live springtails, live myriapods (Chilopoda and Diplopoda), live and dead Diplura, small live spiders, small live pseudoscorpions, one small snail, uncooked hen egg (i.e. piece of cotton wool soaked with fresh whisked hen egg), ant larvae (Gnamptogenys sp.), and live ant workers (Cyphomyrmex sp., Brachymyrmex sp.). Potential food items (arthropods) for Tatuidris were taken from soil samples and Winkler samples (following Silva and Brandão 2010) collected at the site where Tatuidris was a priori determined to be present.
Further observations suggest that Tatuidris may be a sit-and-wait predator. Delsinne observed that "both workers and gynes moved very slowly and were very clumsy. They often remained motionless during several tens of seconds or even several minutes when disturbed (either by my handling or by the contact with another arthropod)." These observations were mainly performed at night, suggesting that Tatuidris may be nocturnal, a hypothesis also supported by collection patterns. For example, in the Río Toachi forest of Ecuador Tatuidris specimens tend to fall in pitfall traps, instead of Winkler sacs. Because pitfall traps usually work 24-h, but Winkler sacs generally uses litter sifted during the day, then ants with nocturnal habits may be underrepresented in Winkler samples. The small eyes of Tatudris species provide further support for this hypothesis.
Specimens of Tatuidris are small (average WbL = 0.62 mm), but specimens can vary greatly in size, with larger specimens being twice as large as the smaller ones (min WbL = 0.45 mm, max WbL = 0.90 mm). Size variability within trap catches (possibly same colonies) may be considerable. For example, workers from one collection catch in Nicaragua varied 30% in size (WbL from 0.65 to 0.85 mm). It is still unclear whether intra-colony size variation is due to the presence of morphological worker castes (e.g. minor and major castes) or continuous size variability. Principal component analysis (PCA) revealed that most variability among specimens is related to size, with shape explaining little of total variation.
Four striking pilosity patterns (patterns of hair-like setae) are known to occur within Tatuidris collections. Pilosity pattern A consists of a mix of both long flexuous and short appressed setae. This is the most common pilosity pattern and the one that most resembles the type specimens from El Salvador and the gyne from Otongachi, Ecuador. Pilosity pattern B is characterized by very short, fully appressed, and regular spaced setae arrayed homogeneously and equidistantly on the head, mesosoma, petiole, postpetiole and gaster. Pilosity pattern C is characterized by dense lanose-looking setae. Pilosity pattern D consists of short and uniform decumbent (strongly inclined but not fully appressed) setae scattered throughout the body.
The relative position of eyes is highly variable within the species. For example, eye location ranges from being completely within the antennal scrobes to completely outside the scrobes. In some cases the eye itself is located outside the antennal scrobe, but the eye's fossa is well marked and confluent with the antennal scrobe. In most specimens, the antennal carina bifurcates from the antennal scrobes and lies straight above the eyes. However, in specimens from Nicaragua, a strongly impressed antennal carina is present. In these specimens about 40% of the eye's area lies within the antennal scrobes. In the gyne, only ~1/6 of the eye lies within the antennal scrobes. A depression sometimes forms in the integument in the sides of the propodeum, below the propodeal spiracle and above the metapleural gland. The depth of this depression varies among specimens and tends to be deepest in larger specimens.
The strength and depth of all sculpture patterns is accentuated in larger sizes. Collections from Nicaragua also tend to present more accentuated sculpture patterns. The head dorsum is usually smooth and shining, except for the area below eyes, which presents longitudinal carinae. The head vertex is covered with transverse carinulae. The lateral surface of the mandible is smooth and shining except for longitudinal superficial striae on the side that vary in depth. The antennal scape is shagreened and superficially areolate. The surface of the ventrolateral part of the pronotum varies strongly across specimens, from smooth and shining to strongly striate, or carinulate. The dorsum of the mesosoma has concentric carinulae and sometimes is slightly punctate. The mesopleuron is smooth and shining except for punctuations and areolae on the ventral margin. The propodeal declivity is smooth with fine transverse striae. The petiole and postpetiole are dorso-laterally strigulate. The gaster is mostly smooth and shiny but sometimes finely and sparsely strigulate.
Workers of Tatuidris present a distinctive morphology, consisting of a shield-like head with a broad vertex, ventrally-turned heavy mandibles which do not overlap at full closure, deep antennal scrobes with eyes at or close to their apex, compact and fused mesosoma, 7-segmented antenna, first gastral segment ventrally directed, and unique among ants – an antenna socket apparatus sitting upside-down on the roof of the expanded frontal lobe.
|Body||Body short and compact. Color ferruginous to dark red. Integument thick and rigid. Body covered by hairs, which are variable in length and inclination.|
|Head||HW = 0.56–1.10 mm. Head shape pyriform (pear-shaped), broadest behind. Maxillary palps one-jointed. Labial palps two-jointed. Labrum bilobed, broader than longer, capable of full reflexion over the buccal cavity. Mandibles opposing in most of their border (except in the tips of the masticatory margin). Masticatory margin with two blunt apical teeth overlapping at closure. Setae (mandibular brush) abundant, present on the ventral side of mandibles. Antenna 7-segmented. Antennal club two segmented, well developed. Scape clavate, gently downcurved at base. Torulus with hypertrophied dorsal lobe and strongly curved downwards. Antennal scrobe present. Antennal socket and antennal scrobe confluent. Antenna socket apparatus sitting upside down on the roof of the expanded frontal lobe. Eyes present, small (REL = 5.41–11.48), located at the posterior apex of antennal scrobe.|
|Mesosoma||Promesonotal suture fused. Metapleural gland orifice round. Metapleural gland opening visible. Metapleural gland bulla separated from annulus of propodeal spiracle by more than the diameter of the spiracle. Katepisternal oblique groove absent. Lower mesopleuron with longitudinal costulae. Propodeum unarmed. Propodeal spiracle, in profile, located at about mid-length of sclerite.|
|Petiole short and sessile. Petiolar ventral process large and rounded. Petiole dorso-ventrally fused. Petiole broadly attached to postpetiole (abdominal segment III). Postpetiolar tergum and sternum overlapping at junction. Postpetiole in dorsal view wider in posterior half.|
|Gaster||Articulation between postpetiole and gastral segment 1 (abdominal segment IV) broad. Postpetiolar postsclerites not set in a concavity or depression. Pretergite of first gastral segment with neck-like constriction. Stridulitrum present on first gastral segment. Limbus (i.e. anterior transverse cuticular ridge of the first gastral segment) absent. Suture between first gastral tergite and sternite anteriorly rounded. First gastral tergosternal suture strong, but not fused. Base of the first gastral sternum in profile rounded. First gastral sternite length is reduced, such that tergite is much larger than the sternite and strongly vaulted. First gastral tergum and sternum smooth or with scattered puncta. Sting present.|
|Legs||Mid and hind tibial spurs present.|
|Source: Donoso 2012, p. 67|
|Body||Body short and compact, with exterior morphology and characters similar to workers. Body covered by hairs. Color yellow, paler than workers. Integument thick and rigid.|
|Head||HW = 1.28 mm. Head shape pyriform, broadest behind. Vertex straight, not concave. Labrum bilobed, broader than long, capable of full reflexion over the buccal cavity. Mandibles opposing in most of their border, except in the tips of the masticatory margin. Masticatory margin with two blunt apical teeth overlapping at closure. Mandibular setae present but less abundant than in workers. Antennal joints 7-segmented. Antennal club two segmented, well developed. Scape clavate, gently downcurved at base. Antennal scrobe present. Antennal socket and antennal scrobe confluent. Antenna socket apparatus sitting upside down on the roof of the expanded frontal lobe. Eyes present, EL = 0.20 mm, eyes larger than in workers (REL = 22.63), located laterally at posterior border of antennal scrobes. Lateral ocelli and median ocellus present.|
|Wings||WingL = 4.60 mm, about 60% longer than total body length. Forewing well developed, with costal cell, basal cell (radial), sub-basal cell (cubital), no vein present between sub-marginal cell 1 and sub-marginal cell 2, R1 vein surrounding sub-marginal cell 3, discal cell 1 and discal cell 2 present, divided by cubital vein which extends a distance similar to the inferior edge of discal cell. Hindwing well developed, with Cu-a vein present. Basal cell completely surrounded by M-Cu and rs-m+M veins.|
|Mesosoma||Promesonotal suture present, not fused. Scutellum broad. Anepisternum and katepisternum broad and shiny, not sculptured. Propodeum armed with a small posteriorly directed spine. Propodeal spiracle in profile at about one-diameter from posterior edge. Metapleural gland present, metapleural spiracle big, longer than broader, within a dorsally directed fold.|
|Petiole broadly attached to postpetiole (abdominal segment III). Postpetiole in lateral view much shorter than gaster (abdominal segment IV).|
|Gaster||Shiny. Vaulted. Constriction between postpetiole and gaster present. Abdominal sternum IX simple, triangular in shape, without spines or lobes. Sting present.|
|Legs||Mid and hind tibia with pectinate spurs present.|
|Source: Donoso 2012, pp. 67–68|
|Body||Body compact, with exterior morphology (except head) similar to workers. Body covered by decumbent setae. Color dark.|
|Head||HW = 0.88 mm. Dorsum with scrabrous-strigate sculpture. Lateral ocelli and median ocellus present. Antenna 12-segmented. Antennal sockets exposed, not covered by frontal carinae, at mid-length from the anterior border of clypeus and the head posterior vertex margin. Antennal scrobes absent. Antennal carinae absent. Scape very short, about 1.3 times as long as pedicel. First flagellar segment relatively short, about the same length as pedicel, slightly curved at base. Antennal club absent, but apical segment is at least 2 times longer than preceding segment. Mandibles reduced, falcate, without differentiated masticatory and basal margins. Mandible edentate, with no visible apical tooth. Clypeus broad, with straight anterior margin. Clypeus does not extend to space between eyes. EL = 0.32 mm, eyes larger than in workers (REL = 48.44) located at mid-length at lateral margin.|
|Wings||WingL = 3.6 mm, about 50% longer than total body length. Venation and cell composition of both fore- and hind-wings similar to that of gyne.|
|Mesosoma||Oblique mesopleural furrow close to but not reaching pronotum. Mesonotum notauli absent. Mesoscutum and mesoscutellum mostly shiny, with small foveae. Pronotum with rugae.|
|Constriction between petiole and postpetiole (abdominal segment III) present. Petiole and postpetiole similar in shape to worker petiole and postpetiole. Petiole broadly attached to postpetiole. Postpetiole, in lateral view, much shorter than gaster (abdominal segment IV).|
|Gaster||Shiny. Vaulted. Constriction between postpetiole and gaster present. Abdominal sternum IX simple, triangular in shape, without spines or lobes.|
|Legs||Hind tibia with 1 pectinate spur.|
|Source: Donoso 2012, p. 68|
- Measurements and indices
- EL. Length of compound eye, at its longest.
- HL. Head length, measured with head in full-face view, from the anterior median clypeal border (not including the clypeal apron) to the median posterior border.
- HW. Head width, measured with head in full-face view. The measure is taken anteriorly to the eyes, where the antenna carina starts. In workers and gynes, HW does not include the eyes. In male, HW includes the eyes.
- REL. Relative eye size (EL × 100/HL).
- WbL. Weber’s length, in lateral view, from the base of anterior slope of pronotum to the lower posteroventral angle of propodeum.
- WingL. Forewing length (male and gyne only).
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