Lachnomyrmex longinodus Fernandez & Baena, 1997

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 : 23

Lachnomyrmex longinodus Fernandez & Baena, 1997

Figures 8, 20

Lachnomyrmex longinodus Fernandez & Baena, 1997 : 110, fig. 1. Holotype worker, COLOMBIA: Narino: Barbacoas, Reserva Natural Privada Rio Nambi , 1200-1300m, 30.iv.1994, F. Escobar col., no. 0423 [ ICNC] (examined) .

Worker diagnosis. Body slender, with fine and primarily longitudinal rugulation; propodeal spines at least twice longer than the distance between their basis; petiole elongate, at least three times longer than broad, in dorsal view; first tergite of gaster sparsely covered by long flexuous hairs.

Holotype measurements. HL 0.72; HW 0.63; ML 0.24; SL 0.49; EL 0.15; WL 0.85; PSL 0.26; PL 0.39; PPL 0.16; GL 0.87; TL 4.49; CI 87; SI 77; OI 24.

Worker measurements (n=1). HL 0.69; HW 0.63; ML 0.24; SL 0.52; EL 0.16; WL 0.84; PSL 0.24; PL 0.36; PPL 0.16; GL 0.82; TL 4.37; CI 90; SI 82; OI 25.

Worker description. Body and appendages reddish to dark brown, contrasting with darker gaster. Head and mesosoma with long, fine, predominantly longitudinal rugulation; mandibles almost entirely smooth and shining, with very short longitudinal striae restricted to the most basal portion; rugae transverse on anterior portion of pronotum, grading to longitudinal on rest of mesosoma; lateral surfaces of pronotum, meso and metapleura, dorsum of propodeum, coxae, and waist coarsely punctate. Pilosity very long, slightly denser on appendages; dorsum of petiole and postpetiole each with around eight long hairs; first tergite of gaster sparsely covered by long flexuous hairs.

Head visibly longer than broad, with vertexal margin only discretely convex; frontal lobes somewhat reduced and rounded laterally; antennal scrobes relatively narrow; eyes well developed, with around nine facets at greatest diameter. Mesosoma considerably slender; promesonotum moderately convex in profile, but well above propodeum level; metanotal groove shallow and broad, with an ill definite posterior limit; propodeal spines straight and very long, about two times longer than the distance between its bases; teeth of propodeal lobes well developed and acute, with little less than propodeal spines half-length. Petiole elongate, around three times longer than broad in dorsal view; petiolar node low, dorsally rounded, and with posterior margin only minimally sloped in lateral view; postpetiole with dorsal surface convex and ventral surface without projections.

Gyne. Unknown.

Etymology. The authors ( Fernandez & Baena 1997) named this species after its long petiolar node. From Latin, longi: long and nodus: node.

Comments. This species is immediately recognizable by the singular body sculpturation, slender mesosoma, and the long propodeal spines and petiole.

Since the original description, L. longinodus was known only by the holotype. However, some weeks before the conclusion of this work, the Colombian colleague Monica Ospina kindly sent us one Lachnomyrmex specimen from the same region where the L. longinodus holotype was collected. The detailed study of this individual led us to confirm its identity as a worker of L. longinodus ; nevertheless, the worker from Ospina's sample presents some slight differences in comparison to the holotype, including longer body rugulation and denser pilosity. These differences could be an effect of the bad condition of the holotype, which has the head mounted apart from the body, antennae lacking apical segments, and the body covered by a great quantity of glue.

The two workers known for this species were collected in the leaf litter of montane wet forests in the occidental slope of the Colombian Andes.

Additional material examined. COLOMBIA: Narino: Barbacoas, RNA El Pangan , 1155m, 01°20'04"N 78°05'24"W, 29-31.iv.1994, A. Miranda & O. Reyes cols, no. T1T6 (1 worker) [ MZSP] .