Lachnomyrmex amazonicus

Lachnomyrmex amazonicus is known from Amazonian Brazil, in 60–200m elevation rainforest. It is one of the few species in the genus occurring in lowland forests rather than in submontane localities. All records refer to workers obtained in samples of sifted litter from the forest floor.

Identification
Feitosa and Brandão (2008) - Body irregularly rugose; promesonotum in profile elevated well above the level of propodeum; metanotal groove weakly impressed to obsolete; propodeal spines slightly directed upwards; teeth of propodeal lobes reduced; dorsum of postpetiole with more than 10 long, flexuous hairs; first gastral tergite entirely devoid of long hairs. The general habitus of this species allies it with Lachnomyrmex longinoi, Lachnomyrmex nordestinus, Lachnomyrmex plaumanni, and Lachnomyrmex victori. These species share the irregular body sculpturation, the obsolete metanotal groove, and the absence of long hairs on the first tergite of gaster. However, L. amazonicus can be distinguished from these species by the combination of promesonotum strongly convex, propodeal spines directed upwards, and dorsum of postpetiole bearing more than 10 long hairs.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil.

Nomenclature

 *  amazonicus. Lachnomyrmex amazonicus Feitosa & Brandão, 2008: 11, figs. 2, 20 (w.q.) BRAZIL.

Worker
Holotype. HL 0.58; HW 0.58; ML 0.16; SL 0.31; EL 0.11; WL 0.66; PSL 0.14; PL 0.28; PPL 0.13; GL 0.76; TL 2.57; CI 100; SI 54; OI 18. (n=6). HL 0.52–0.66; HW 0.54–0.66; ML 0.16–0.21; SL 0.31–0.41; EL 0.08– 0.13; WL 0.57–0.74; PSL 0.11–0.17; PL 0.22–0.29; PPL 0.12–0.15; GL 0.68–0.82; TL 2.26–2.84; CI 100– 103; SI 50–63; OI 13–19.

Color dark reddish-brown to blackish, with waist and gaster slightly lighter; appendages yellowish to light brown. 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 longitudinal striae restricted to basal portion; petiole and postpetiole finely and irregularly rugose. Abundant pilosity on head and mesosoma dorsum; dorsum of petiolar node and postpetiole each with more than 10 long, flexuous hairs; first gastral tergite entirely devoid of long hairs. Head as long as broad, with vertexal margin weakly convex; frontal lobes laterally rounded; eyes with about seven facets on maximum diameter. Promesonotum strongly convex in profile, elevated well above the level of propodeum; metanotal groove shallow to virtually obsolete; propodeal spines slightly directed upwards; teeth of propodeal lobes reduced, with around one-third of propodeal spines length. Petiolar node moderately elevated, dorsally rounded, and with the posterior face weakly sloped in lateral view; postpetiole feebly convex dorsally and without ventral processes.

Queen
Differing from worker by the larger eyes, with around 14 facets at maximum diameter; propodeal spines straight, without the apexes curved upwards.

Type Material
Holotype worker. BRAZIL: Pará: Parauapebas, Fl. Nacional de Carajás, Garagem, 06º02'54S 50º04'55W, 25.iv–02.v.2008, Rogério R. Silva col., no. 5. Paratypes. same data as holotype, no. 1 (1 worker) ; same data, no. 4 (1 worker) same data (1 worker) ; same data, no. 5 (1 worker) ; same data (1 worker) ; same data, nos. 1/2/3/4/5 (5 workers and 3 gynes) [MZSP]; BRAZIL: Amazonas: Manaus, 22.ix.1993, A.B. Casimiro col., no. 4829 (1 worker) ; iii-iv.1994, R. Didham col. (3 workers) ; same data (1 worker) [MZSP]; Mato Grosso: Alta Floresta, 10º47'S 56º49'W, 28.iv.1999, H.L. Vasconcelos col. (1 worker) [INPA]; Pará: Melgaço, Caxiuanã, 1º44'9S 51º29'15"W, 27–29.i.2003, A.Y. Harada, E.P. Fagundes, P. Batra, R. Calisto & Mó cols, no. 5 ; 1º45'15S 51º31'20"W, 23–25.i.2004, A.Y. Harada, E. P. Fagundes, R. Calisto & Mó cols, no. 5 (1 worker) [MZSP]; Parauapebas, Fl. Nacional de Carajás, Casa de Hóspedes, 06º03'41S 50º03'13W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [MZSP]; Núcleo Urbano, 06º03'53S 50º03'42W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [MZSP]; Zoobotânico, 06º03'41S 50º03'13W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [MZSP].

Etymology
The name refers to the region from where this species is known, the Amazon Basin.

References based on Global Ant Biodiversity Informatics

 * Feitosa, R.M. and C.R.F Brandao. 2008. A taxonomic revision of the Neotropical myrmicine ant genus Lachnomyrmex Wheeler (Hymenoptera: Formicidae). Zootaxa 1890:1-49
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.