Lachnomyrmex pilosus

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Lachnomyrmex pilosus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Lachnomyrmex
Species: L. pilosus
Binomial name
Lachnomyrmex pilosus
Weber, 1950

Lachnomyrmex pilosus psw8571-4 profile 1.jpg

Lachnomyrmex pilosus psw8571-4 dorsal 1.jpg

Specimen labels

Individuals are commonly encountered in the leaf litter of wet forests, from lowland to submontane areas (200–1430m).

Identification

Feitosa and Brandão (2008) - Body irregularly rugose; metanotal groove narrow and deeply impressed; apex of propodeal spines curved upwards; petiolar node rounded dorsally; dorsum of petiolar node and postpetiole each with more than 10 long hairs; first tergite of gaster entirely covered by long flexuous hairs. The smaller size and well defined metanotal groove separate this species from the related Lachnomyrmex laticeps. Although the workers of L. pilosus and Lachnomyrmex scrobiculatus are easily distinguishable, the gynes of these species are quite similar. Gynes of L. pilosus can be separated from L. scrobiculatus by the rounded petiolar node and by the absence of an anteroventral process on the postpetiole.

There is considerable geographical variation among specimens of L. pilosus, mainly in body size. Individuals collected in the eastern Amazon Basin are relatively small, while specimens from central Brazil and Peru are usually large. Intermediate forms can be found in the remaining localities of northern South America.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Neotropical Region: Bolivia, Brazil, Colombia, Ecuador, Grenada, Peru, Trinidad and Tobago (type locality), Venezuela.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Very little is known about the biology of these cryptic ants. Workers are frequently found in leaf litter and soil samples processed in Winklers or Berlese extractors, but these ants are never especially abundant within samples. When a dealate gyne is found associated with workers in 1m2 samples of leaf litter, normally it is found singly, which suggests that colonies are relatively small and apparently monogynic; workers and nests are extremely difficult to spot in the field, because the workers are very slow moving and well camouflaged; if there is any leaf-litter nest structure, it is destroyed during sifting, but our impression is that they do not construct any permanent nidal structure. Species of Lachnomyrmex apparently nest within the leaf litter, inside natural cavities of the superficial soil layers, fallen logs, and rotten wood, as evidenced by the large number of soil-covered individuals collected, from information recorded in specimen label data, and from observations of collectors. Workers forage alone, in the leaf litter and in the low vegetation, occasionally among epiphytes and moss, probably preying on small soft-bodied arthropods and possibly harvesting plant exudates. (Feitosa and Brandao 2008)

Castes

Nomenclature

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

  • pilosus. Lachnomyrmex pilosus Weber, 1950c: 1 (w.) TRINIDAD. Feitosa & Brandão, 2008: 31 (q.).

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Feitosa and Brandão (2008):

Worker

Holotype HL 0.70; HW 0.68; ML 0.24; SL 0.43; EL 0.16; WL 0.77; PSL 0.16; PL 0.30; PPL 0.17; GL 0.92; TL 3.10; CI 97; SI 63; OI 24. Worker measurements (n=30). HL 0.54–0.72; HW 0.55–0.72; ML 0.18–0.26; SL 0.46–0.35; EL 0.11– 0.17; WL 0.60–0.85; PSL 0.13–0.20; PL 0.25–0.35; PPL 0.18–0.13; GL 0.66–0.96; TL 2.37–3.30; CI 93–102; SL 59–70; 19–27.

Color light reddish-brown to dark brown, with appendages lighter. Body densely covered by vermiculate short rugae, forming irregular areolae on promesonotum; rugae somewhat longer and longitudinal on head dorsum and slightly sparser on mesopleura and lateral surfaces of propodeum; mandibles with short striae restricted to basal portion; petiole and postpetiole irregularly rugose. Abundant pilosity, except by dorsal surface of propodeum; dorsum of petiolar node and postpetiole and first gastral tergite densely covered by long flexuous hairs. Head as long as broad to longer than broad, with vertexal margin relatively short and only weakly convex; frontal lobes rounded laterally; eyes with about seven facets on maximum diameter. Promesonotum considerably convex in profile; metanotal groove narrow and deeply impressed; apex of propodeal spines curved upwards; teeth of propodeal lobes well developed, reaching propodeal spines half-length. Petiolar node elevated and rounded dorsally in lateral view; postpetiole moderately convex and with sternite only feebly projected.

Queen

(n=7). HL 0.60–0.73; HW 0.57–0.73; ML 0.20–0.25; SL 0.35–0.49; EL 0.16–0.21; WL 0.76–1.04; PSL 0.15–0.20; PL 0.31–0.39; PPL 0.16–0.19; GL 0.94–1.10; TL 2.98–3.71; CI 96–100; SI 60–66; OI 27–30.

Eyes with about 13 facets at greatest diameter; wings with the basic pattern of venation for the genus; bases of propodeal spines with around five long flexuous hairs; petiolar peduncle slightly longer than in the conspecific workers, with a discrete anteroventral tooth.

Larva

Feitosa and Brandão (2008), after Wheeler & Wheeler 1989 - Length (through spiracles) 2.4–2.9mm. Head hairs 0.038–0.125mm long, scarce (about 25), shaft curved and smooth. Body hairs very sparse, long, generally distributed. Fours types present: (1) 0.06–0.10mm long, with slightly curved shaft and short frayed tip, on ventral half of body; (2) 0.125–0.3mm long, with curved shaft and small apical bulb, on dorsal half of body; (3) about 0.016mm long, few, smooth, with flexuous shaft and uncinate tip; and (4) 0.19–0.22mm long, with flexuous shaft, anchor-tipped, four hairs in a transversal row across dorsum of abdominal segments I–III and V, and six on abdominal segment IV. Cranium subhexagonal, slightly wider than long, dorsal border feebly concave. Antennae at midlength of cranium, large, three closely spaced sensilla on a sclerotized slight elevation on a feebly stained, large raised teardrop-shaped base. Maxilla small with abruptly narrowed apex; palp and galea subequal in height; palp subcylindical with five (two apical with a spinule each, two large subapical and encapsulated, and one lateral with a rather long spinule) sensilla; galea subconical with two apical sensilla. Labrum small, bilobed, anterior surface with 12 sensilla on and near the ventral surface; ventral surface with minute spinules in the impression; posterior surface spinulose, the spinules coarse an isolated, with about 20 sensilla; anterior surface of labrum with short transverse rows of rather long spinules; palp short paxilliform, with five sensilla similar in length to maxillary sensilla; sericteries opening as a short transverse slit in a slight depression. Hypopharynx with a few short transverse rows of minute spinules dorsally. Mandibles heavily sclerotized laterally and apically, blade less sclerotized; apical tooth narrow and curved medially; blade with a rather stout-based apical tooth, a smaller subapical tooth, and a few denticles near teeth. Body with few distinct somites. Spiracles small, decreasing slightly posteriorly. Integument on venter of thoracic segments I–III and abdominal segments I–III with a few minute spinules; abdominal segments VII–X more spinulose.

Etymology

Feitosa and Brandão (2008) - Weber (1950) certainly named this species after its abundant pilosity. From Latin, pilosus: hairy.

Determination Clarifications

In the description of Lachnomyrmex larvae (Wheeler & Wheeler 1989) and in the first record of the genus for Venezuela (Lattke 1991), the authors refer to the examined specimens as L. scrobiculatus. However, we have studied the material mentioned in both studies and concluded that these specimens actually belong to L. pilosus.

References

  • Feitosa, R.M. & Brandão, C.R.F. 2008. A taxonomic revision of the Neotropical myrmicine ant genus Lachnomyrmex Wheeler (Hymenoptera: Formicidae). Zootaxa 1890, 1-49.
  • Weber, N. A. 1950d. New Trinidad Myrmicinae, with a note on Basiceros Schulz (Hymenoptera, Formicidae). Am. Mus. Novit. 1465: 1-6 (page 1, worker described)