Lachnomyrmex amazonicus Feitosa & Brandão, 2008

Feitosa, Rodrigo M. & Brandão, Carlos Roberto F., 2008, A taxonomic revision of the Neotropical myrmicine ant genus Lachnomyrmex Wheeler (Hymenoptera: Formicidae), Zootaxa 1890, pp. 1-49 : 11-13

Lachnomyrmex amazonicus Feitosa & Brandão , new species

Figures 2 , 20

Holotype worker. BRAZIL: Pará: Parauapebas, Fl. Nacional de Carajás, Garagem, 06º02'54''S 50º04'55''W, 25.iv–02.v.2008, Rogério R. Silva col., no. 5 [ MZSP].

Paratypes. same data as holotype, no. 1 (1 worker) [ CASC]; same data, no. 4 (1 worker) [ CPDC]; same data (1 worker) [ ICNC]; same data, no. 5 (1 worker) [ USNM]; same data (1 worker) [ WMPC]; 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) [ INPA]; iii-iv.1994, R. Didham col. (3 workers) [ BMNH]; 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, 1º44'9''S 51º29'15"W, 27–29.i.2003, A.Y. Harada, E.P. Fagundes, P. Batra, R. Calisto & Mó cols, no. 5 [ MPEG]; 1º45'15''S 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, 06º03'41''S 50º03'13''W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [ MZSP]; Núcleo Urbano, 06º03'53''S 50º03'42''W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [ MZSP]; Zoobotânico, 06º03'41''S 50º03'13''W, 25.iv–02.v.2008, Rogério R. Silva col., no. 1 (1 worker) [ MZSP].

Worker diagnosis. 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.

Holotype measurements. 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.

Worker measurements (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.

Worker description. 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.

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

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

Comments. The general habitus of this species allies it with Lachnomyrmex longinoi , L. nordestinus , L. plaumanni , and L. 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.

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.

Figures

FIGURE 2. Paratype worker of Lachnomyrmex amazonicus from Pará, Brazil: A, head in full face view; B, lateral view; C, dorsal view. Image by Michele Esposito, specimen CASENT 0173882.

FIGURE 20. Distribution map for the Lachnomyrmex species (L. amazonicus, L. longinodus, and L. victori).