Lachnomyrmex pilosus Weber, 1950

Feitosa, R. M. & Brandão, C. R. F., 2008, A taxonomic revision of the Neotropical myrmicine ant genus Lachnomyrmex Wheeler (Hymenoptera: Formicidae), Zootaxa 1890, pp. 1-49 : 31-32

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Lachnomyrmex pilosus Weber, 1950


Lachnomyrmex pilosus Weber, 1950 View in CoL   HNS

Figures 1, 12, 18

Lachnomyrmex pilosus Weber, 1950 View in CoL   HNS : 1. Holotype worker, TRINIDAD: British West Indies, Macqueripe Bay , 5.viii.1935, N. Weber col., no. 260 [ AMNH] (examined) ; Wheeler & Wheeler 1989: 321 (larvae description, as L. scrobiculatus   HNS ); Lattke 1991: 60 (first record for Venezuela, as L. scrobiculatus   HNS ).

Worker diagnosis. 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.

Holotype measurements. 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.

Gyne measurements (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.

Worker description. 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.

Gyne (first description). Eyes with about 13 facets at greatest diameter; wings with the basic pattern of venation for the genus (Fig. 1); bases of propodeal spines with around five long flexuous hairs; petiolar peduncle slightly longer than in the conspecific workers, with a discrete anteroventral tooth.

Mature larva (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. Weber (1950) certainly named this species after its abundant pilosity. From Latin, pilosus   HNS : hairy.

Comments. The smaller size and well defined metanotal groove separate this species from the related L. laticeps   HNS . Although the workers of L. pilosus   HNS and L. scrobiculatus   HNS are easily distinguishable, the gynes of these species are quite similar. Gynes of L. pilosus   HNS can be separated from L. scrobiculatus   HNS 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   HNS , 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.

In the description of Lachnomyrmex   HNS 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   HNS . However, we have studied the material mentioned in both studies and concluded that these specimens actually belong to L. pilosus   HNS .

Lachnomyrmex pilosus   HNS occurs in Trinidad and central-northern South America, including many localities in northern Brazil, Bolivia, Colombia, Ecuador, Peru, and Venezuela. Individuals are commonly encountered in the leaf litter of wet forests, from lowland to submontane areas (200-1430m).

Additional material examined. BRAZIL: Amazonas: Manaus , iii - iv.1994, R. Didham col. (12 workers) [ BMNH] ; 20.x.1994, A.B. Casimiro col., no. 4832 (1 gyne) [ CPDC] ; Amapa: Macapa, Rod. Duque de Caxias , Km 9, 19.x.1997, J.M. Vilhena col., no. 261 (1 worker) [ INPA] ; Para: Marituba , 1°22'S 48°20'W, 22.x.2004, J.R.M. Santos col. (1 worker) [ CPDC] GoogleMaps ; Melgaco, Caxiuana , 1°42'23"S 51°27'32"W, 30.x.2003, A.Y. Harada, E.P. Fagundes, C.E.D. Sanhudo, C.A.R. Moura & J.L.P. Souza cols (1 worker) [ INPA] GoogleMaps ; 23- 25.i.2004, A.Y. Harada, E.P. Fagundes, C.E.D. Sanhudo & Joca cols (4 workers) [ MPEG] GoogleMaps ; Tocantins: Novo Jardim , 11°50'26"S 46°41'11"W, 9.x.2004, R.R., Silva & B.H. Dietz (2 workers) [ MZSP] GoogleMaps ; BOLIVIA: Cochabamba: Lagunitas, 109km E Cochabamba , 1.ii.1999, R. Anderson col., no. 18644 (2 workers) [ WPMC] ; COLOMBIA: Amazonas: Araracuara, Cor. via Putumayo , 10.vii.1994, G. Ganghi col., nos. 72098/72100 (2 workers) [ IHVL] ; Meta: R. Neeva, Rod. Vallaro , 15.v.1977, D. Jackson col. (1 worker) [ BMNH] ; Narino: Orito, Territorio Kofan , 00°30'N 77°13'W, 25-28.ix.1998, E. L. Gonzalez col., nos. 72101-72108 (11 workers and 1 gyne) [ IHVL] GoogleMaps ; same data, nos. 72109/72110 (2 workers) [ MZSP] GoogleMaps ; ECUADOR: Morona Santiago: Los Tayos , 3.vii.1976, Tjitte de Vries col. (1 gyne) [ MZSP] ; Napo: Limoncocha , 00°24'S 76°36'W, 12.viii.1973, L. Morales col., no. 304 (1 worker) [ MZSP] GoogleMaps ; PERU: Amazonas: Ramon Castillo, 5km NW Leticia , 23.ii.1972, S. Peck & J. Peck cols (2 workers) [ MZSP] ; Cuzco: Campamento Cashiriari , 11°51'1"S 72°46'45"W, 15-, J. Santisteban et al. cols, nos. 0201596/0201597 (2 workers) [ MUSM] GoogleMaps ; Madre de Dios: Los Amigos Field Station , Huangana, 12°34'8"S 70°6'3"W, 6-9.x.2004, T.R. Schultz, C. Marshall & J. Sosa-Calvo cols, nos. 446595-446597 (3 workers) [ USNM] GoogleMaps ; TRINIDAD: Blue Basin ,, B. Pitkia col. (1 worker) [ BMNH] ; VENEZUELA: Bolivar: Campamento Rio Grande , 08°07'N 61°42'W, 14.viii.1986, P.S. Ward col., no. 8571.4 (1 worker) [ MIZA] GoogleMaps ; no. PSW8571- 4 (1 worker, examined by images) [ UCDC] GoogleMaps ; Sucre: El Pilar , 10°33'N 63°09'W, 1.ix.1986, J.E. Lattke col., no. 1027 (7 workers) [ MIZA] GoogleMaps ; same data (2 workers) [ MZSP] GoogleMaps ; Tachira: Las Cuevas , 44 NW S. Cristobal , 07°48'N 71°46'W, 29.xii.1999, J.E. Lattke col. (1 worker and 1 gyne) [ MIZA] GoogleMaps ; S. Cristobal, La Florida , 9.xii.1985, J.E. Lattke & W.L. Brown cols, no. 727 (5 workers) [ MIZA] ; Via Sta. Ana, Rio Frio , 14.viii.1983, J.E. Lattke & G. Borges col. (1 worker) [ MIZA] .


USA, New York, New York, American Museum of Natural History


United Kingdom, London, The Natural History Museum [formerly British Museum (Natural History)]


Brazil, Bahia, Itabuna, Centro de Pesquisas do Cacau


Brazil, Amazonas, Manaus, Instituto Nacional de Pesquisas da Amazoonia, Colecao Sistematica da Entomologia


Brazil, Para, Belem, Museu Paraense Emilio Goeldi


Brazil, Sao Paulo, Sao Paulo, Museu de Zoologia da Universidade de Sao Paulo






Peru, Lima, Universidad Nacional Mayor de San Marcos, Museo de Historia Natural


USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]


Venezuela, Maracay, Museuo del Instituto de Zoologia Agricola


USA, California, Davis, University of California, R.M. Bohart Museum of Entomology














Lachnomyrmex pilosus Weber, 1950

Feitosa, R. M. & Brandão, C. R. F. 2008

Lachnomyrmex pilosus

Weber, N. A. 1950: 31

Lachnomyrmex pilosus

Weber, N. A. 1950: 31
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