Trachymyrmex relictus

AntWiki - Where Ant Biologists Share Their Knowledge
Jump to navigation Jump to search
Trachymyrmex relictus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Trachymyrmex
Species: T. relictus
Binomial name
Trachymyrmex relictus
Borgmeier, 1934

Trachymyrmex relictus casent0901691 p 1 high.jpg

Trachymyrmex relictus casent0901691 d 1 high.jpg

Specimen Labels

Synonyms

Found in both forest habitats and in open fields.

Identification

Mayhé-Nunes & Brandão (2002) - Both worker and female of Trachymyrmex relictus may be separated at once from the remaining species of the present group by the presence of long propodeal spines, the dorsally armed petiolar node, and the rather scarce hairs. The relatively long lateral pronotal spines (longer than the anterior mesonotal ones) are shared with Trachymyrmex compactus, which is nevertheless quite distinct by the postero-dorsally excised postpetiolar node and by the presence of one spine at each side of the antero-inferior corner of pronotum. The projecting, hornlike apex of antennal scrobe and the high and conical mesonotal spines distinguish Trachymyrmex opulentus from T. relictus.

In all examined samples the workers have the second pair of mesonotal projections variable, from blunt teeth to small spines; the slender propodeal spines are thickened in some specimens, and the posterior pair of denticles of the petiole is absent in the Zulia, Venezuela sample.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Brazil, French Guiana, Guyana, Suriname (type locality), Trinidad and Tobago.

Distribution based on AntMaps

AntMapLegend.png

Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Mayhé-Nunes & Brandão (2002) - This species occurs both in primary forest and in open, cultivated fields, and its nests are often found within the limits of Atta nests. The number of nest chambers is unknown, but at least in one case the upper chamber was at a depth of 20 cm beneath the surface. The nest of a colony discovered by Weber (1968: 143) had as an entrance a bare hole of 10 mm in diameter. Alate forms (sexes not indicated) were present in the latter colony on August 31, 1967. These are timid animals that feign death upon touch.

Castes

Worker

Queen

Male

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • relictus. Trachymyrmex relictus Borgmeier, 1934: 107, figs. 6, 7 (w.q.) SURINAM. Mayhé-Nunes & Brandão, 2002: 689 (m.). Senior synonym of fitzgeraldi: Mayhé-Nunes & Brandão, 2002: 686.
  • fitzgeraldi. Trachymyrmex relictus subsp. fitzgeraldi Weber, 1937: 401 (w.) TRINIDAD. Junior synonym of relictus: Mayhé-Nunes & Brandão, 2002: 686.

Type Material

Mayhé-Nunes & Brandão (2002) - Worker; female; Suriname: Paramaribo; Brazil, Para: Belem. Para types of T. relictus: 3 workers (MNRJ); 3 females, 40 workers (Museu de Zoologia da Universidade de Sao Paulo); 1 female, 2 workers (Instituto de Biologia Universidade Federal Rural do Rio de Janeiro) (examined); syntypes of T. relictus fitzgeraldi: 1 worker (MZSP); 3 workers (National Museum of Natural History) (examined).

According to Borgmeier (1934) the holotype of T. relictus should be deposited at the “Instituto de Biologia Vegetal”; as far as we know this collection should have been first transferred to Sao Bento, Rio de Janeiro, then to Pinheiral, RJ and finally to the CECL. However, we were unable to find it there. Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Mayhé-Nunes & Brandão (2002) - TL 3.5-4.7; HL 0.84-1.05; HW 0 .81-1 .03; IFW 0.49-0.60; ScL 0. 76-0.89; TRL1.19-l.54; HfL 1.11-1.35. Light medium brown, head and gaster darker with reddish hues. Integument opaque, indistinctly shagreened. Hairs of variable length, yellowish brown, abundant yet conspicuously scarcer than in Trachymyrmex opulentus, short and strongly curved on sides of head and alitrunk, on femora and gastric sternum, also on dorsum of head and gastric tergum where they are interspersed among more numerous, longer hairs; hairs on scapes and legs oblique to subdecumbent but not appressed. Dense, very short pubescence of lighter color curved or inclined on head, alitrunk, pedicel and gaster, appressed on scapes and on legs, including the extensor face of the latter.

Head. Mandibles smooth and shining except laterally on base and mesially on proximal half of masticatory margin, where they are finely striate; masticatory margin with one apical and 8 subapical teeth, gradually smaller towards the mandibular base. Frontal lobes semicircular, conspicuously expanded laterad, the interfrontal width well surpassing one half of head width across the eyes. Frontal carinae straight, diverging caudad, fading out at posterior fourth of head. Front vertex and occiput with sparse piligerous tubercles. Preocular carinae very slightly curving mesad above eyes, not intersecting the antennal scrobe, fading out behind eyes at a distance from the posterior orbit which is less than the diameter of the latter. Posterior half of antennal scrobe indistinctly delimited, its apex scarcely projecting in a tuberous fashion, but marked by a small tooth. Supraocular tumulus rather vestigial. Occiput in full-face view nearly rounded laterad, shallowly notched in the middle. Carinae of vertex distinct but blunt, the longitudinal groove between the carinae and the transverse groove in front of them distinct but shallow. Occipital tooth conspicuous, although very small is more developed than in any other species in the group. Inferior occipital corner rounded. Eyes moderately convex, about 10-11 facets in a row across the greatest diameter. Antennal scapes shorter than length of head capsule, little surpassing the occipital corner when lodged in the scrobe. All funicular segments distinctly longer than broad.

Alitrunk. Pronotum with vestigial humeral angles, its antero-inferior corners spinous, the dorsolateral spines high, well-developed. Mesonotum with a pair of very low, multituberculate anterior tumuli followed, in side view, by a similar still lower pair of rather spinous projections; the third pair in the form of very small denticles. Metanotal groove impressed. Basal face of propodeum narrow, laterally partly marginate by an incomplete denticulate ridge. Propodeal spines well developed, slender, oblique, pointed, apically usually a bit deflected downward, but longer than the lateral pronotal spines. Hind femora shorter than length of thorax.

Waist and gaster. Petiole pedunculate, node proper about as broad as long, the dorsal armature of two pairs of denticles always developed , the first pair often vestigial, the second pair always strong. Antero-ventral process of petiole absent. Postpetiole shallowly excavate above postero-mesially, the postero-dorsal border not excised. Tergum I of gaster with minute, evenly distributed but rather indistinct piligerous tubercles; its dorsum antero-laterally marginate.

Queen

Mayhé-Nunes & Brandão (2002) - TL 5.5-6. 1; HL 1.13-1.24; HW 1.16-1.24; IFW 0.67-0.73; ScL0.95-l.OO; TRL1.73-1.97; HfL 1.46-1 .54. With the same general distinguishing characters as the workers, with the following differences: three ocelli on vertex, the lateral ones smaller. Pronotum with a pair of strong and truncated scapular spines, directed out and forwards, and with a pair of inferior spines pointed down and forwards, smaller than the scapular ones. Mesoscutum surmounted by minute piligerous tubercles, without notable dorsal projections. With the ali trunk in oblique dorsal view, shallow parapses delimited by the parapsidial furrows; mesothoracic paraptera more or less impressed, with a narrow median portion; scutellum ending in two stout and blunt spines, directed backwards, with the sides converging obliquely inwards; meta thoracic paraptera concealed by the scutellum; propodeal spiracle orifices visible. Two strong acute spines on propodeum. Petiolar dorsum with a pair of small teeth. First gastric tergite with a longitudinal ridge on each side; disk with two longitudinal series of small piligerous tubercles, absent in the middle of the segment.

Wings pale brown, completely covered by microtrichia. Fore wing with 5 closed cells (submedian, median, costal, submarginal and marginal); anal vein turned up and fusing with cubito-anal vein, not prolonged beyond the junction. Pterostigma conspicuous, although not pigmented. Hind wing with 5 complete veins, and 2 closed cells; 7 hamuli on anterior margin.

Male

Mayhé-Nunes & Brandão (2002) - TL 4.0; HL 0.71; HW 0.78; IFW 0.76; ScL 0.76; TRL 1.41; HfL 1.70; FWL 3.8; HWL 2.7 (only one specimen measured). Ferruginous; occipital half of head a bit darker; antennae and legs testaceous. Pilosity as in worker and female, longer inclined or recurved hairs mixed with very fine and short pubescence on body and appendages.

Head. Mandibles finely punctuated on dorsal surface; masticatory margin with only the five basal teeth evident, gradually diminishing toward base (the three additional teeth rudimentary); external margin slightly sinuous. Median border of clypeus moderately convex, with a small anterior notch; dorsal disk of clypeus without notable projections. Frontal lobes rounded and directed forwards, leaving part of the antennal insertions exposed. Frontal carinae divering caudad, not reaching the occiput. Preocular carinae distinct, fading out at the posterior border of eyes. Compound eyes big and convex, filling some 1/2 of the sides of head. Ocelli prominent. Antennae with 13 segments; scape clearly surpassing the occipital corners, nearly three times longer than funicular segments I-III combined; funicular segment I slightly longer than II. Occipital corners rounded, without projections in frontal view. Occipital margin gently concave in the middle between the lateral occelli.

Alitrunk: Pronotum with a scapular spine in form of a short, acute tooth. Scutum narrow and superficially impressed Mayrian furrows; parapsidial furrows and parapsis rudimentary. Mesothoracic paraptera, in dorsal view, slightly narrowed in the middle, where it is impressed and presents a short longitudinal keel, without side projections. Scutellum without dorsal projections, ending as two short, stout and blunt spines, pointing backwards. Metathoracic paraptera concealed by the scutellum in dorsal view. Propodeum with a pair of blunt spines between basal and declive faces.

Waist and gaster: Dorsum of petiole without projections. Postpetiole a little broader than petiole, in dorsal view, superficially impressed above, with the posterior border concave. First gastric tergite without lateral ridges or piligerous tubercles.

Wings as described to the female above, but smaller.

Karyotype

  • n = 10, 2n = 20, karyotype = 20M (Brazil) (Barros et al., 2013).

References